Is astronomical twilight always seen when the sun is 18 degrees under the horizon?

Is astronomical twilight always seen when the sun is 18 degrees under the horizon?

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Is astronomical twilight always seen when the sun is 18 degrees under the horizon or are there other factors that may influence it?

It's the very definition of astronomical twilight.

Civil twilight is when the sun is 6° below the horizon.

Nautical twilight is at 12°.

Astronomical twilight is at 18°.

These are also defined by activities. Civil twilight is the period following sunset when it's still bright enough outside to practice most activities. Nautical twilight is when it's dark enough to see at least a few stars, so that sailors can use them for dead reckoning. Finally, astronomical twilight is when the sky is at its darkest.

These values are convenient definitions rather than descriptions of an observable condition.

So astronomical twilight is defined to be when the sun is between 12 and 18 degrees below the horizon. Nothing special happens as the sun moves from 11.999 degrees to 12 degrees, and nothing special happens when the sun moves from 17.999 to 18 degrees.

So astronomical twilight isn't something that is seen. It's not an observable. But it is generally the case that by the time that the sun is 18 degrees below the horizon, the sky is pretty nearly as dark as it is going to get.

Clearly after the sun sets, the sky gets gradually darker and darker. It is a continuous process. It is convenient for humans to split up this continuum into chunks, and it is convenient for humans to do so using the position of the sun. There is nothing deeper about 18 degrees.

The daily prayers are an integral part of a Muslim's life. In order to fulfill their religious obligation, it is important for all Muslims to know the timings of the daily prayers. To know the timings of zuhr and maghrib prayers has never been a problem but to know the timing of subh prayer has not been easy.

Previously, Muslims used to rely on the mu'azzin of their neighbourhood mosques who would mostly use visual senses to determine the time of subh prayer. Even now, the Muslims living in the Muslim countries do the same.

However, the Muslims in the West are deprived of the benefits of neighbourhood mosques and their azan. Therefore, they have come up with a time-table which can be used by all Muslims in their homes.

In preparing a prayer time-table, it is easy to find the timings of zuhr and maghrib prayers from any observatory or astronomical institution: one can easily ask the scientific institution for the times of “noon” and “sunset” because the definitions of “noon” and “sunset” are common knowledge.

The difficult arises in determining the time for subh (dawn) prayer. How do you define “subh” or “fajr” for the Western astronomer or scientist? How do you explain the difference between the “false” dawn and the “true” dawn?

In this article, with the help of Allah subhanahu wa ta'ala, I intend to discuss the definition of dawn and see how can we relate it to the existing scientific classifications of twilights and daybreak.

Summarising 18 Degree Prayer Timetable

Over the years we have published a number of articles on the topic of the beginning time of Fajr and ʿIshā’ during the summer periods for northern cities of Europe affected by a phenomena called Persistent Twilight when the physical signs for Fajr and ʿIshā no longer appear for a period of a few days to weeks. This article is a brief summary with some further clarifications to what has seemingly become quite a complicated topic for masājid and their congregations.

The importance of the Prayer is something the Jurists of Islām in all ages have never taken lightly, for it is indeed the first thing that we will be held to account for on the Day of Reckoning.

The Messenger of Allāh (sall Allāhu ʿalayhi wa sallam) said,

“The first deed that the servant will be held to account for on the Day of Judgement is the prayer. If it is good, he will be successful and safe, but if it is not good, he will be of the unfortunate and wretched”.[1]

It is in this light that we need to carefully consider the time for our prayers and the start of our fasting closely.

The Hizbul ʿUlamā’ timetable is one that has been adopted by a number of mosques around the UK including the recent ‘Unified prayer timetable for London’ adopted by East London Mosque, Regents Park Mosque and many other large mosques. The fact that these organisations have sought to unite the Muslim community is an extremely praiseworthy matter, indeed unity is one of the most important factors that leads to the strengthening of the Muslim community and I commend them for their sincerity. However, it must be noted that this timetable has adopted times which are in opposition to virtually all the Major fiqh councils from across the Muslim world from North America, through the Middle East and the Indian Subcontinent. Due to the adoption of this timetable by many mosques and the reality that the much earlier time for Fajr makes it seemingly more difficult, there is a general feeling that this timetable is the norm and what has been agreed upon by the majority of jurists is actually abnormal and cannot be true.

With the fast being a very much private worship between the worshipper and His Lord, the individual obligation of a person to ensure they are fasting at the correct times is even more important.

Allāh (subḥānahu wa taʿālā) says: “The fast (Sawm) is for Me and I will reward it.”[2]

So, simply relying on the decision of the Imām in this matter does not remove the burden on the individual. To believe that this issue can be left with the masjid to decide is an incorrect approach to have and we Muslims should exercise some more care and concern relating to our personal worship, even if we consider ourselves laymen. As Allāh (subḥānahu wa taʿālā) addresses the lay people with this Quranic guideline:

“O you who have believed, obey Allāh and obey the Messenger and those in authority among you. And if you disagree over anything, refer it to Allāh and the Messenger, if you should believe in Allāh and the Last Day. That is the best [way] and best in result”.[3]

Although most scholars agree on both the shar’ῑ signs given in the divine text concerning the start of Fajr, they disagree on how to interpret the shar’ῑ signs as actual astronomical phenomena. The conceptualising of this astronomical phenomena can be difficult for many of us and even much more in areas where the phenomena seems to breakdown due to the northerly position of many cities in North Europe. But with this in mind, it is important for individuals and their masājid to consider the following before deciding on what they believe is the correct timetable and in protecting their fasts in particular.

Need your own personal Ramaḍān Timetable?

Please consider the following points:

1. The 18 degree opinion is the opinion held by the vast majority of Major Fiqh councils from North America all the way across to the Indian Subcontinent. This position which can mean very early Fajr start times in Northern Europe during the Summer has been a position not only held in recent times but over centuries. In recent times the lower angle of 15 degrees held famously by the Islamic Society of North America Fiqh Council was changed to 17.5 degrees in September 2011 this means the determination for Fajr is virtually uniform across the globe.

* ISNA traditionally held the latest Fajr time due to an adopted angle of 15 degrees. But in September 2011 they revised their position to 17.5 degrees which is more or less in line with the rest of the World. [4]

** It has been widely attributed to them to hold the position of 19 degrees which is even earlier Fajr or a position of 90 mins after Maghrib for ‘Isha. Although in using calculation of 18 degrees the times for Fajr are virtually the same in Makkah which indicates that the 90 minute position is in effect the same as 18 degrees and due to its equatorial position this does not change much at all throughout the year.

2. Some of those who have misrepresented the 18 degrees position have claimed that it is an angle arrived upon by astronomers using an incorrect definition of what is Fajr. They mention that 18 degrees is representative of Astronomical twilight which is effectively total darkness and this is not Fajr. The reality is that the angle was not decided upon by reading definitions made by astronomers but was done by carrying out observations (Mushāhada) whose times were then translated into an angle which would allow people in any location to determine their prayer times easily. In the same way even the Hizbul Ulama timetables/Unified prayer timetables have not got observations for every single location but rather they did a few observations and then calculated the rest through extrapolation.

It should be further noted that the Hizbul Ulama/Unified Prayer timetable when engineered backwards produce times which are more closely reflective to an angle of 12 degrees or even less. Not only is this a major departure from all other Major Fiqh councils. When looking at the astronomical phenomena related to 12 degrees as described by astronomers, this is an even more unlikely description to suit the shar’ī description for Fajr. This strange position results in people starting their fast sometimes 2.5 hours after the standard position.

The matter for beginning our fast/Fajr times was not based on an astronomical description as is commonly misunderstood. Rather observations have been done across the globe and even across centuries whose times were then related to the angle of the Sun below the horizon. The vast majority corresponding to 18 degrees. This then set the platform for astronomers to then produce methods of calculating the time for Fajr wherever a person or mosque was based in the World. So the 18 degree method is clearly based on observations and by scholars who certainly knew the distinction between the false Fajr (al-Fajr al-Mustatīl) and the true Fajr (al-Subh al-Sādiq).

3. The reasoning that we should only rely on physical observation (Mushāhadah) and that calculation is not from the sunnah has been heavily discussed and to avoid repeating this discussion, we will just mention two points. The first being that in many places, due to adverse weather conditions, weakness of eyesight and even lack of persons who know how to interpret the actual shar’ī sign, it may not be possible for there to be a physical observation for each day. So the sunnah allows for one to estimate through extrapolating the time from a previous day through calculation. As Allāh (subḥānahu wa taʿālā) says about prayer times:

“Perform As-Salāt (Iqāmat-as-Salāt) from mid-day till the darkness of the night (i.e. Dhuhr, ʿAsr, Maghrib, and ʿIshā’ prayers), and recite the Qur’ān in the early dawn (i.e. the Morning Prayer). Verily, the recitation of the Qur’ān in the early dawn is witnessed.” [5]

This verse establishes that prayer times are linked to actual astronomical phenomena rather than seeing it with the naked eye, in contrast to the ḥadῑth concerning the start of Ramadān which is linked to the notion of physically sighting the moon and not depending on astronomical actualities. The Prophet (sall Allāhu ʿalayhi wa sallam) said,

“Fast when you see the moon and cease your fast when you see the moon.”[6]

It is the consensus of classical Muslim scholars that astronomical calculations cannot be used as a replacement for actually sighting the moon (for Ramadān) with the naked eye. This is the difference between sighting the moon, which is needed to confirm the start of the month of Ramadān or Hajj, and the sighting of the twilight which is used to decide prayer times.

In summary, we hope everyone understands that the Hizbul Ulama / Unified Prayer timetable are actually a departure from the norm. As it goes against the vast majority, we need to consider first personally and then communally which timetable to follow as in these Summer months there is over 2.5 hours in difference between the start of Fajr and hence the time we start fasting. This is not the case of taking the easiest position and what some people term as ‘fatwa shopping’ but remembering that our prayer is the first thing we will be accounted for and that the fast is a very personal private worship between our Lord and ourselves and we would wish not to jeopardise this in especially the most auspicious of months, Ramadān.

As a final point to be mentioned as per clarification on how Fajr times are calculated, during the days of persistent twilight, on and on Muwaqqit. com both of whom have websites which provide timetables and smartphone-based apps.

We are all aware in the Summer, the further north we travel the longer the day becomes and the shorter the night becomes. The time and distance the Sun travels below the horizon become shorter and shorter the further north we travel. If we understand that the shar’ī’ sign indicating the appearance of Fajr occurs when the Sun is approximately 18 degrees below the horizon. Then there comes a point in the Northern hemisphere which includes the UK and other northern European countries that the Sun for a short period of time in the Summer eventually doesn’t actually go below 18 degrees and stays above this point. So what does that mean?

This gives rise to the phenomena known as Persistent Twilight, where the sky never goes totally dark and there is a redness in the sky throughout the night. So the sign we would traditionally look for to indicate the beginning of Fajr never appears. This phenomena occurs for around 2 months during the Summer in parts of the British Isles and gets longer the further north you travel.

In light of this phenomena, we have determined that during this period where we cannot visibly see the shar’ī sign of Fajr, that we determine Fajr by using what is known as Solar Midnight. Solar midnight is the lowest point the Sun reaches below the horizon. The logic behind this being that from this point forward, ie this moment in time. The Sun begins to rise and the light in the sky starts to brighten for the first time in the night. It is this time that we have determined to be the beginning of Fajr and the time we start fasting.

A number of early jurists who were renowned astronomers explicitly calculated the latitude of lands which would experience persistent twilight and explained that dawn there would occur at solar midnight.

Quṭb al-Dīn al-Shīrazī (raḥimahu Allāhu), a ninth century Shāfiʿī jurist, expert astronomer and polymath says,

“Where the latitude is 48.5°… shafaq (the twilight of Maghrib) will be connected to dawn … It is classified as morning as long as the sun is in the east and it will be classified as shafaq as long as the sun is in the west.” [7]

ʿAbd al-ʿAlī al-Barjandī (raḥimahu Allāhu), a tenth century Ḥanafī jurist and expert astronomer says,

“When the latitude exceeds 48.5°, dawn and shafaq intertwine as is mentioned in the books but it is clear that when the sun is in the west it is classified as shafaq and when it is in the east it is classified as dawn.” [8]

For further information and more detailed discussions, including the methodology employed by us to calculate the prayer times especially in Summer when the signs of Fajr disappear, please refer to these previously published articles:

  • The transparency overlay has a large outer circle with the Universal Time (see below) marked on it. The set of smaller concentric circles are circles of altitude above the horizon (which is the outermost of these circles). This represents the part of the sky that you can see from your latitude. The heavy line is the limit for altitude = 18 degrees (when the sun reaches this limit it is the beginning or end of twilight). The offcenter circle is the path of the sun through the year the ecliptic. The vertical line passing through the circles of altitude represents the meridian, the imaginary line passing through the zenith (directly over head) and the north celestial pole (an extension of the Earths north pole into the sky).

    Select a date and local time, then convert the local time to UT (remember to use a 24 hour clock).

    Rising is defined as when an object passes above zero degrees elevation, (although if you have mountains or other obstructions on your horizon you can set the elevation limit for rising to an arbitrary number).

    Select a star that you can identify on the star chart on the insert. Find this star in the sky.

    Rotate the insert until the stars inside the horizon circle more or less match up with the sky that you see.

    The ecliptic is defined as the path of the Earth around the sun, or as seen from Earth, the path of the sun through the sky projected on the stars. This is drawn as the off center ellipse on both sides of the insert. You can plot the position of the sun along this, to estimate where the sun is at any given time (you can look these up yourself in the magazine Sky & Telescope).

Summer Skywatching: July's Twilight Nights

June 21, the day of the northern summer solstice, was hailed by much of the mainstream media as "the longest day of the year." But I've always been of the opinion that this term is somewhat misleading.

Actually, the longest day of the year comes on the first Sunday of November, when we set our clocks back one hour at 2 a.m. to account for the end of daylight saving time and return to standard time. By virtue of adjusting our timepieces back one hour, we're making the day 25 hours long.

A much better way to define the summer solstice would be to say that this is the day with "the longest period of daylight." And yet here too we probably would run into a misinterpretation. For most mid-northern locations at or around 40 degrees north latitude, the sun is above the horizon for about 15 hours on this day. [Earth's Solstices & Equinoxes (Infographic)]

That might lead some to say that at the time of the summer solstice there are 15 hours of day and 9 hours of night. Not true!

The twilight zone

When the sun is below the horizon, what we experience is not always necessarily what one would refer to as "night." Indeed, there is a period called twilight, which occurs just before sunrise and right after sunset. The glow we see in the pre-sunrise sky we have come to call "dawn" the interval right after sunset is what we call "dusk."

The reason we have twilight is that the sun illuminates Earth's atmosphere for a while before it rises and after it sets. The predictions of astronomical twilight in most almanacs are based on the rule that dusk ends (or dawn begins) when the center of the sun's disk is 18 degrees below the horizon — a standard measurement that dates all the way back to the time of Claudius Ptolemy, around 130 A.D.!

That 18-degree figure refers to the end of astronomical twilight, when the sky is totally dark — nighttime. At this particular time of the year at mid-northern latitudes (around 40 degrees north), twilight can last two hours. So from two hours prior to sunrise to two hours after sunset, the sky is not completely dark — meaning that what we call "night" really only lasts for about five hours. [Spot Planets and a Meteor Shower: July 2014 Skywatching Video]

Different twilight definitions

There are two other forms of twilight in addition to astronomical twilight.

Nautical twilight is when the center of the sun lies 12 degrees below the horizon and only general or vague outlines of objects are visible. This is the point when the horizon becomes difficult to perceive (in the evening) or starts to be distinguishable (in the morning).

The term dates back to the days when sailing ships navigated by using the stars. Indeed, at the beginning or end of nautical twilight, many of the brighter stars — those of 1st and 2nd magnitude — are visible to the unaided eye.

Civil twilight, on the other hand, is when the center of the sun lies 6 degrees below the horizon. At this time, there is enough light for objects to be clearly distinguishable outdoor activities can commence (dawn) or end (dusk) without artificial illumination.

Civil twilight is the definition of twilight most widely used by the general public. In some newspapers, for instance, you might see a notation on the weather page: "Turn lights on," which refers to the end of civil twilight when drivers are to turn on their headlights.

No night at all

Twilight lasts even longer at more northern latitudes. When one reaches 49 degrees north (the Canadian city of Winnipeg, for example), astronomical twilight does not end at all around the time of the summer solstice. And in northern parts of Eurasia and North America, bright twilight can last through much of the night.

From Glasgow, Scotland, for instance (latitude 55.9 degrees), astronomical twilight persists all night long from May 6 through Aug 7 and nautical twilight lasts from June 4 through July 9. And heading north of latitude 60 degrees, civil twilight lingers through the night (sometimes referred to as "white nights").

North of the Arctic Circle (latitude 66.5 degrees), the sun remains above the horizon for 24 hours on the summer solstice, reaching its highest point at local noon, and then appearing to skim just above the northern horizon at midnight — the so-called "midnight sun."

At this time of year, the northernmost portions of Norway, Sweden and Finland are experiencing this effect. In northern Canada, one place where you can see the midnight sun is the small Inuit hamlet at Resolute on Cornwallis Island. It has been said that "Resolute is not the end of the world, but you can see it from here."

Home to about 215 people and 110 houses, Resolute is also known as "Qausuittug"("place with no dawn"). Indeed, the sun shines for 24 hours a day there from April 29 to Aug. 13.

Tropical nights

The length of twilight depends on how long the sun takes to drop 18 degrees below the horizon. At the equator, where this motion is perpendicular to the horizon, twilight lasts only 75 minutes.

That's why people who live in northern climes are usually surprised how quickly it gets dark at this time of year when they venture south for a tropical vacation.

Where they live, some perceptible light in the western part of the sky might persist for two hours or more after sunset, but from Central America and the Caribbean, the sky for all intents and purposes has already become quite dark just an hour or so after sunset.

HM Nautical Almanac Office: Miscellanea

Twilight is the time preceding sunrise and following sunset when the sky is partially illuminated. In polar regions twilight can persist for long periods when the Sun is below the horizon for extended periods of time. A definition of sunrise and sunset is a helpful starting point in this description of twilight.

Sunrise and sunset are taken to be the times at which the apparent upper limb of the Sun is on the (astronomical) horizon. For our purposes, they are computed by calculating when the zenith distance of the centre of the Sun's disk is 90° 50′, adopting 34′ for horizontal refraction and 16′ for the semi-diameter of the Sun.

The term depression can also be used in the context of an object's position relative to the horizon. The depression of an object is its angular distance below the horizon i.e. the zenith distance of the object minus 90°. Hence, the depression of the centre of the Sun's disk at sunset is 50′.

For the purposes of this discussion, a reference to the summer solstice means the northern hemisphere summer solstice taking place on or about June 21st.

The Astronomical Almanac tabulates the following times of twilight in addition to the times of sunrise and sunset.

    Beginning of morning civil twilight / End of evening civil twilight.

The beginning of morning civil twilight and the end of evening civil twilight occur when the zenith distance of the centre of the Sun's disk is 96°.

For latitudes north of approximately 60.5° north, civil twilight will not occur around the summer solstice. Civil twilight occurs all year round for nearly all of the UK except the northernmost parts of the Shetland Islands e.g. Yell, Fetlar, Unst and the northern part of Mainland. For example, civil twilight does not occur at Norwick on Unst between June 13 and June 29.

The beginning of morning nautical twilight and the end of evening nautical twilight occur when the zenith distance of the centre of the Sun's disk is 102°.

For latitudes north of approximately 54.5° north, nautical twilight will not occur around the summer solstice. The table below shows the period for which nautical twilight does not occur for a sample of UK locations.

Location No nautical twilight
EdinburghfromJune 2toJuly 11
InvernessfromMay 23toJuly 20
Kirkwall fromMay 16toJuly 27
Lerwick fromMay 11toAugust 1

The beginning of morning astronomical twilight and the end of evening astronomical twilight occur when the zenith distance of the centre of the Sun's disk is 108°.

For latitudes north of approximately 48.5° north, astronomical twilight will not occur around the summer solstice. The table below shows the period for which astronomical twilight does not occur for a sample of UK locations.

LocationNo astronomical twilight
St. Helier fromJune 8toJuly 4
Southampton fromMay 26toJuly 17
Birmingham fromMay 18toJuly 25
Leeds fromMay 13toJuly 31
Edinburgh fromMay 5toAugust 8
Inverness fromApril 30toAugust 13
Kirkwall fromApril 25toAugust 18
Lerwick fromApril 22toAugust 21

For a typical location in non-polar regions, the normal daily sequence of events and the corresponding zenith distance (Z.D.) and depression (Dep.) of the Sun is as follows:

Daily sequence of eventsZ.D.Dep.Illumination conditions
(Ignoring the effects of moonlight)
Beginning Morning Astronomical Twilight 108°18°Sixth magnitude stars are no longer visible to the naked eye under good conditions
Beginning Morning Nautical Twilight102°12°It may now be possible to discern the sea horizon and it is no longer dark for normal practical purposes.
Beginning Morning Civil Twilight96°Large terrestrial objects can be now be distinguished. The sea horizon is clearly defined and the brightest stars and planets are still visible.
End of the Hours of DarknessN/AN/AEnds 30 minutes before sunrise as defined by the United Kingdom Road Vehicle Lighting Regulations (1989) and always occurs during civil twilight in the UK.
Sunrise90° 50′50′Daylight
Sunset90° 50′50′
Beginning of the Hours of DarknessN/AN/ABegins 30 minutes after sunset as defined by the United Kingdom Road Vehicle Lighting Regulations (1989) and always occurs during civil twilight in the UK.
End Evening Civil Twilight96°Large terrestrial objects can be seen but no detail can be distinguished. The sea horizon is clearly defined and the brightest stars and planets are visible.
End Evening Nautical Twilight102°12°The sea horizon is no longer visible and it can be considered to be dark for normal practical purposes.
End Evening Astronomical Twilight108°18°Sixth magnitude stars are now visible to the naked eye under good conditions.

By way of a historical footnote, sunrise, sunset, moonrise and moonset times were first introduced into The Nautical Almanac and Astronomical Ephemeris in 1925. Astronomical twilight followed in 1928 and nautical and civil twilight were first tabulated in 1937.

Further information on twilights can be found in HMNAO Astronomical Information Sheet No. 7, A note on sunrise, sunset, and twilight times and on the illumination conditions during twilight.

A guide to our updated interactive Almanac

Illustration credit: Ade Ashford. While there are several excellent commercial and open-source astronomy software packages available that can model the sky for virtually any time and place on Earth, accurately and in exquisite graphical detail, sometimes we just need answers to simple questions: When will the Moon set during next Friday’s star party? Is Jupiter’s Great Red Spot visible tonight in Tokyo? Can I see Mercury in the morning twilight from Rome? Answers to all these questions and more can be found quickly with our updated Almanac.

Although some of you will have already had a sneak preview of our updated online Almanac via links from recent Observing stories, we thought that it probably deserved a post of its own. Here, then, is our guide to exploring some of the new interactive Almanac’s enhanced features. We will explore more advanced themes in a subsequent post, but first a topical question concerning the visibility of all five bright naked-eye planets in the morning sky.

Example: Is Mercury currently best seen from Rome, Italy or Sydney, Australia?
Innermost planet Mercury attains a greatest elongation of 26 degrees west of the Sun at 1am GMT on Sunday, 7 February. This means that it is furthest from the Sun in the pre-dawn twilight and best placed for morning observation. So, is Mercury currently easier to see in the Northern or the Southern Hemisphere?

Observing circumstances from Rome, Italy
Launch the Almanac and first enter “2016/02/07” into the Date window (remember that the format must be year/month/day &mdash �-2-7” or �/2/7” are equally acceptable &mdash but don’t type the quotes) and the Universal Time/GMT “01:00” into the Time window (again without the quotes) and click the Calc button. The Almanac recomputes the new data. (Clicking Reset, incidentally, always restores the Almanac to the current date and time.)Next, go to the extreme upper right of the Almanac where you find the new twilight selector pull-down menu. Here you can determine the local time of Astronomical twilight (when the Sun is -18 degrees below the horizon), Nautical twilight (Sun -12 degrees below the horizon), Civil twilight (Sun -6 degrees below the horizon) or Bright planets last/first visible (Sun -9 degrees below the horizon) &mdash we need the latter to determine when innermost planet Mercury is just fading into the bright twilight and highest in the morning sky.Next, use the Country and City menus to select first “Italy” then “Rome” from the alphabetised pull-down lists. The Almanac will recompute and display localised data for Rome. Important note: the Almanac knows the time zones for all cities in its database, but currently requires you to know if the location observes Daylight Savings Time and to select/deselect it accordingly ( is a great resource if you are unsure). Since it’s currently Northern Hemisphere winter, we can be confident that Rome isn’t using DST in February, so the DST box should be unticked.Next, we use the plus/minus hour and minute buttons to step forward/backward in time such that the Local Date & Time window displays the Rome time displayed in the Bright planets last visible window (i.e., 06:31 am). Now we can examine the observational data in the planetary data table.We can see that on 7 February, Mercury rises at 05:56 am local time and at 06:31 am the Sun is indeed -9 degrees below Rome’s east-southeast horizon, rising at 07:17 am local time. At 06:31 am when the sky is not so bright as to render planet Mercury invisible in a clear sky, yet late enough for the innermost planet to reach its highest in twilight, we see that Mercury is +5 degrees high in the southeast.

Furthermore, the information box under the current Moon phase information states that the 28-day-old, 3 percent illuminated waning lunar crescent is 3 degrees above Rome’s east-southeast horizon and 8 degrees from magnitude zero Mercury, while the latter is 5 degrees from magnitude -4 Venus.

Observing circumstances from Sydney, Australia
Use the Country and City menus to select first “Australia” then “Sydney” from the alphabetised pull-down lists. The Almanac will recompute and display localised data for Sydney, NSW. The Almanac knows the time zone difference for Sydney, but currently requires you to know if the city observes Daylight Savings Time and to select/deselect it accordingly (remember to use if you are unsure). Since it’s currently Southern Hemisphere winter, we can be confident that Sydney, NSW is using DST in February, so ensure that the DST box is ticked.The Bright planets last/first visible option is still selected, so we can see that Mercury will be highest in the morning sky and just fading into dawn twilight at 05:42 am local time in Sydney, Australia on 7 February. As before, use the plus/minus hour and minute buttons to step forward/backward in time such that the Local Date & Time window displays the Sydney time of 05:42 am. All done! Now we can examine the observational data in the planetary data table.We can see that on 7 February in Sydney, Mercury rises at 04:24 am local time and the Sun rises at 06:22 am local time. At 05:42 am when the sky is not so bright as to render planet Mercury invisible in a clear sky, yet late enough for the innermost planet to reach its highest in twilight, we see that Mercury is +15 degrees high in the east-southeast &mdash in other words, three times higher in Sydney’s sky compared to Rome for the same level of dawn twilight!

Furthermore, we can see that Mercury rises almost a full two hours before the Sun as seen from Sydney, NSW on 7 February 2016, whereas in Rome the innermost planet rises about 1&frac13 hours prior to sunrise. The reason for the difference? Well, the angle that the ecliptic makes with the morning horizon in February is steeper in Australia compared to Italy, giving Southern Hemisphere observers a distinct advantage for currently viewing all five bright naked-eye planets in the morning sky.

Astronomical Twilight of the Gods

We can consider here if you like the concepts that the Egyptians associations with the rising of the Sun, the manifestation of Ra, the magical process that was envisioned around this, Heka through which all things arose, and also consider the Egyptian esoteric usage of the Pentagram with regards to this.

“I am he whom the Lord of all made before duality had yet come into being … I am the son of him who gave birth to the universe … I am the protection of that which the Lord of all has ordained … I am he who gave life to the Ennead of gods … I have come to take my position that I may receive my dignity. Because to me belonged the universe before you gods had come into being. You have come afterwards because I am Heka.”

Another epithet for Heka was “the one who consecrates imagery” (HkA-kA). It refers exactly to the primeval generative attribute of Heka to empower the creator’s divine thoughts and actions and translate them into their substantial equivalent in the visual and material world. Heka was the animation force behind every ritual act, state or private, beneficent or hostile

The creative act of Heka is personified and depicted on the solar bark of the creator god Re. In company with Su (“creative logos”) and Sia (“perception”), Heka re-enacts the creation of the first time and the separation of heaven and earth. The theological manifestation of Heka is present in tomb and temple representations as early as the Old Kingdom.

‘I am one with Atum when he still floated alone in Nun, the waters of chaos, before any of His strength had gone into creating the cosmos. I am Atum at His most inexhaustible – the potence and potential of all that is to be. This is my magic protection and it’s older and greater than all the Gods together, The Perfect youth, sweet of love,Who repeats the births again and again

As can be seen then Heka was the underlying magical premise of all Creation, the translation from the invisible to the visible, from darkness to light, from the immaterial to that having form, and the birth of the Sun encapsulated all these concepts.

In order to achieve this the Sun needed to emerge from the Duat, the sign for which was the Pentagram, the encircled five pointed star, why the Egyptians should have decided upon this as a symbol needs to be determined. The first considered usage of the Pentagram Symbol is thought to date back to Uruk circa 3,200 BC, there it was the UB sign and related to the four quarters of the cosmos and also importantly The Four Winds, thus the sign could be understood as animating the spiritual qualities associate with these winds/directions, hence its relationship to 'magic'

The basis for the ideogram is cycles of the Planet Venus in terms of the viewed relationship from Earth perspective, with regards to it's visual merging and remerging from the Sun over 584 day periodics, alternating as a Morning or Evening star, and thus also very closely associated with sunrise and set, it's this association needs to be considered closely.

The Egyptians were aware that the first angle for Astronomical Twilight was at 18 degrees below the horizon, beneath which no light appears over the horizon, in the iconography of the Dream Stela located at the Sphinx this is expressed in geometric symbolism, were the first offering is made marking this point below the horizon, the unseen birth of Ra, the next offering is at 9 degrees above the horizon line, associate with the first hour of the day, as can be learnt from Egyptian Sundials, these angles of course directly relating to those of the Pentagon.

The Sphinx Temple itself also contains within its architectural design the geometric proportions relating to the Morning and Evening stars, their relationship to Sunrise and set, the entering of the Sun into the Duat, and this relationship to the four directions, there were originally ten statues placed upon the plinths around the inner courtyard, also are seen six pillars either side outside of this representing the tentyfour hours of the days circuit.

Venus itself was understood as the eye of Hathor, she who in her Morning star aspect was as a fierce Lioness, and as the Evening star the cow eyed Goddess of pleasure, this complimented the eye of Horus represented by the planet Mercury, which as Morning Star embodied the principle of Divine Kingship, as Evening Star associate with Seth.

These two eyes of Ra, the planets of inferior orbit closely related to the Sun, represented the Male and Female aspects bound as One, it is Heka that pre-determines Duality and binds it as twin serpents.

To the right Thoth can be seen measuring out the proportions of the axis which relates to the symbolism of the opening of the Double Doors of Heaven, this represents the magical opening into the Duat itself, related to the concept of the Double Doors of Heaven, again the esoteric usage of the Pentagram, were A is to B as B is to C.

This motif would often be seen on the canopic outer containers which held the four jars containing the organs of a deceased, an aspect of the cult of Osiris and the Duat, in order to overcome the serpent of Chaos, Apophis, it was important to known the words to enable passage.

The sysmbolism of the Pentagram will also be bound up with this translation between realms were Anubis is seen as guardian of the double bolted gateway. It's esoteric usage in such a context of course is the basis for the Pentagram of the Magic Circle, the divide between the material and immaterial, light and darkness, and also the relationship between four quarters or guardians dating back at least to Uruk.

In terms of the greater Necropolis, such as Giza it is considered the pyramid itself represented the power of Ra, but also i would consider that the small cult Pyramids related to Horus, and the Queens Pyramids to Hathor, and their respective eyes.

The two pits that flank the upper temple East of the pyramid house boats that were probably for Khufu as Horus. These pits are oriented North and South. This orientation may relate to the power of Horus which was written in ancient texts to have extended from the North to the South. Their location near the upper temple suggests that these boats were also connected with the living King because the temple's design is thought to have been based on the palace of the living King as Horus

The first boat pit may have been connected with the Cult of Hathor who was one of the triad of deities of Giza. The Pyramid complex was dedicated to the Gods Re, Hathor and Horus

So a few interesting considerations then.

Yes i'm sure that's derivative of Heka.

In these myths Phanes is often equated with Eros and Mithras and has been depicted as a deity emerging from a cosmic egg, entwined with a serpent. He had a helmet and had broad, golden wings. The Orphic cosmogony is bizarre, and quite unlike the creation sagas offered by Homer and Hesiod. Scholars have suggested that Orphism is "un-Greek" even "Asiatic" in conception, because of its inherent dualism. Time, who was also called Aion, created the silver egg of the universe, out of this egg burst out the first-born, Phanes, who was also called Dionysus. Phanes was a uroboric male-female deity of light and goodness, whose name means "to bring light" or "to shine" a first-born androgynous god of light who emerges from a void or a watery abyss and gives birth to the universe.

Many threads of earlier myths are apparent in the new tradition. Phanes was believed to have been hatched from the World-Egg of Chronos (Time) and Ananke (Necessity) or Nyx in the black bird form and wind. His older wife Nyx (Night) called him Protogenus. As she created nighttime, he created daytime. He also created the method of creation by mingling. He was made the ruler of the deities and passed the sceptre to Nyx. This new Orphic tradition states that Nyx later gave the sceptre to her son Uranos before it passed to Cronus and then to Zeus, who retained it.

Wow, another mind blowing thread!

I can say with confidence that you author the very best threads on ATS second to none.

Egyptian knowledge of the cosmos and mathematics has always fascinated me.

Thanks for helping connect the dots as always.

Venus hold's a close association with Egyptians for a good reason, there is let us say some significant connections between these parts of the all, but it must also be mentioned that they (the Egyptians) lost there way with what was given, and therefore should be viewed with slight caution.

none the less a quality thread and good work

Thanks very much for the praise, i enjoy figuring out the mystery religions of the past. The Egyptians did have a beautiful metaphysical system of thought based upon natural observations and this translated into symbolic representation, and it really shows in the quality of their arts, crafts and architecture, so always a pleasure to contemplate them.

There are complications with Venus as far as Egyptology goes, from the Pre-Dynastic period until toward the end of the Old Kingdom i would say the planet was represented by the Lion Goddess Sekhmet Hathor as the Morning Star and the Cow Goddess as the Evening, complications begin with the introduction of Osiris who among his many attributes is also Venus Morning Star and referred to as 'the crosser' in astronomy texts, there is also a fusion of Hathor-Isis to some degree, this due to importing Near Eastern resurrection cults, probably from Byblos.

But you perhaps had something else in mind.

Wow that would be scary if the first thought of the Universe was Satanic. my fault for posting baboons in the first image maybe, but really the Divine youth is an eternal innocent.

In many ways Heka is the basis for the aspect of Nefer-Atum in the rising of the Sun which i detailed here, except that Heka is at the Universal level, so the magic of childhood and the awakening into eternal life based upon that premise.

I have really enjoyed reading your threads and this one in particular.

When I first looked at the looping picture above it reminded me of the retrograde movements of Venus and the other planets.

Looking at the icons and way the ancients depicted them it suggests to me they are 2representing how man first evolved. So, in modern terms ancient man always knew about the spirit world and acknowledge a creator - the Eternal One - I wonder if this is the point in our existence where, as adrogenous (for humankind) we separated into man and woman from the animal kingdom, which propr to our separation was the norm. We have evolved somehow and one can see in an adrogenous plant we have both male and female flowers on it as well as androgynous .

I then wonder if the people, as they looked back remember the story of the earth's originans as 'The supernatural Eternal one' sending the first one whom many thought of naturally as his supernatural son, which some religions believe to be Lucifer, the Bringer of light, and also viewed as Venus etc who went on to produce the necessary 'forces' (angels) to create our earth. In this way as Lucifer gets converted to Saturn and onto Satan we see the ancient astrological way of thinking (astrologically linked to solid/material things like eg the infrastructure of a planet and the body and especially boundaries. Recently I read the Gnostic Gospels from Nag Hammadi and a delightful story is told in several of the documents contained therein. Samael - another name for Satan creates the world by emitting huge numbers of angels to do the work and once it is done, he then claimed to the angels to be the original and only God whom they are all to worship. When he has made his claim, which incidentally the angels knew was not right, espeically when he adds that 'He is a jealous and only God and there were none other than him, a female voice coming from the heavens proclaimed "I don't think so Samael!" Just from this one link we get the origins of the first two commandments for men and the dislike for the knowledge of the women.

I suspect that much of the iconography from many peoples has been destroyed by the church as blasphemous depictations so we can only go on what is left.

So often we look at the snake encircling man yet we never seem to think other than its a snake, but perhaps it might also make sense if its seen as a sperm and its importance in our creativity, especially in the egg icons. Gnostis taught that man is a God when he becomes pure and is equal to Christ and in effect joins him by seeking purity and divinity within himself - not through a priesthood officiating for him to God which explains the desperate destruction the early church carried out. These tales are told throughout many cultures, the link is always to the original Eternal Being.

Wow that would be scary if the first thought of the Universe was Satanic. my fault for posting baboons in the first image maybe, but really the Divine youth is an eternal innocent.

In many ways Heka is the basis for the aspect of Nefer-Atum in the rising of the Sun which i detailed here, except that Heka is at the Universal level, so the magic of childhood and the awakening into eternal life based upon that premise.

Well, Satan is the lord of the physical. And is commonly considered to be Lucifer, the light bringer.

Is the overall imagery a match? Not really. But there are some key points there.

Keep in mind, much of what Satan is derives from Christian dogma more than anything else. It could be taht elements of various deities were included as a way to discredit. Who knows. but there are some symbolic similarities between the two.

ETA: i agree with other posters. You are a great thread author, and I look forward to devouring each and every one.

Yes when i consider qualities of Satan i only really go off his archetypal role in the Book of Job, were he represents the negative aspect of Saturn, undermining over time physical health, social standing, faith and idealism, mental faculties, familial relationships and just about anything else that can be subverted and corroded, and is in direct opposition to principles of Jovian establishment.

To apply those traits to Heka or Phanes it would have been the case of first consciousness arising, deciding everything was worthless crap and going back to sleep, it is unlikely much of a Universe would have been created

It's hard to find any sort of direct equivalent for Satan in ancient Egyptian thought, the closest is the ageing aspect of the Atum, which given the transition from youth to aged/death over time has suggested an association with Chronos/Saturn, but this would generally have been in terms of natural observance that all things fade and wither over time rather than willful infliction and malevolent application. Seth had his violently disturbed ways but he was no Satan either.

The looping principles in the last illustration relate to the principles of horizontal Sundials. Ancient traditions such as Egypt and Sumeria did tend to look at Creative spiritual progression in terms of a singular continuum were the Masculine and Feminine in metaphysical terms reflect differing degrees of dynamism and divergence, that contrasting forces are the essence of Creation and thus they arose both Male and Female.

The fall of Lucifer/Star of the Morning in Isaiah relates to Babylon and it's King Nebuchadnezzar, the Divine namesake Nebu was the Babylonian equivalent of Mercury and that is the star in question, in many way it's a celebration of Saturn bringing him down given he falls into the Earth in being brought low, is eaten by maggots and other unpleasant things.

The Talmudic Samael does seem to relate quite closely to Satanael but i don't think he's linked to the descent of the Angels to Earth in early sources, later times he becomes seen as responsible for all the woes of the world though.

Keep in mind, much of what Satan is derives from Christian dogma more than anything else. It could be taht elements of various deities were included as a way to discredit. Who knows. but there are some symbolic similarities between the two

I used to think pretty much the same thing, but have since reconsidered.

The reason? Some years ago when I was reading the Mahabharata for the first time, I was surprised and curious to see the name "Satanika" listed as one of the warriors killed in the infamous Kurukshetra War.

I did an Internet search on the name and much to my surprise ended up at several Hindu "What to name your baby" sites. I scrolled down the "S" names for boys and was seriously taken aback to find the name 'Satanand' listed meaning Vishnu and the name 'Satanath' given as a name for Shiva. I found the same names listed on a number of similar sites.

Curious, I checked the "official" lists for the 1000 names of Vishnu and Shiva & didn't find any names beginning with Satan. Yet the names definitely appear as Hindu names for boys, so I ultimately had to conclude that at some time in history the Hindu god system prefixed their god names with 'Satan" and these names are still remembered and revered among the common folk.

The Near and Middle East certainly did experience wave after wave of Aryan invasions of people, so I must assume they were familiar with the Vedic gods as well. I can only conclude that at some point in ancient history, it was commonly known in the Middle East that the Vedic god names were prefixed by the name Satan.

Is astronomical twilight always seen when the sun is 18 degrees under the horizon? - Astronomy

Sunrise 1st: 04.46 30th: 04.44

Sunset 1st: 21.27 30th: 21.41

Earliest sunrise: 17th at 04.39

Latest sunset: 24th at 21.42

Day length 1st: 16.40.54 30th: 16.56.58

21st is the Summer Solstice, when the Sun reaches its most northerly point in the sky and is overhead at local noon along the Tropic of Cancer. It is also the first day of astronomical summer, forecasters are predicting a heatwave around this time - fingers crossed they are right, if we have to have such short nights, at least let us have some warm days.

Partial solar eclipse visible from Manchester: 10th between 10.06 and 12.26. Maximum, 25%, at 11.15. See Highlights for more details.

Astronomical darkness: none

Astro twilight 1st: 23.39 to 02.36 30th: 00.05 to 02.19

Full Moon: 24th at 19.39 (angular diameter 33’ 01”)

Lunar Apogee: 8th at 03.28 (406228 Km, angular diameter 29’ 24”)

Lunar Perigee: 23rd at 10.59 (359959 Km, angular diameter 33’ 10”)

The June Full Moon is most commonly called the Strawberry Moon, as this is the time when the ripening fruit is gathered. This name was also used by the Algonquin and Ojibwa tribes of N America. Other names given in the Old Farmers Almanac are the Birth Moon, the Blooming Moon, the Egg Laying Moon, the Hatching Moon, the Hot Moon and the Hoer Moon - this one because now is the time when newly sprouting plants need lots of attention.

Celtic names are the Horses Moon and the Mead Moon, it’s the Chinese Lotus Moon, the Neo Pagan’s Planting Moon, the Medieval English Dyan Moon and the Inuit’s Hunting Moon. It was the Colonial American Rose Moon and among the many names used by Indigenous American people were the Cherokee Green Moon, the Choctaw Windy Moon and the Dakota Sioux Moon When the June Berries are Ripe.

Astronomers are currently suffering from an excess of light - no astronomical darkness throughout June, and not even a great deal of astro twilight. It begins around midnight and only lasts 3 hours at the start of the month, down to 2 hours around the time of the solstice on 21st.

The upside to this is that there is a chance of seeing some noctilucent clouds, when the Sun is between 6 and 16 degrees below the horizon, 60 to 90 minutes after sunset and before sunrise. As the sky is not completely dark, these wispy silver or blue coloured clouds are best seen away from light polluted towns and cities. The most likely time for spotting some is said to be in the morning nautical twilight, ideally when the Sun is 10 degrees below the horizon.

Jupiter is now higher in the morning sky, reaching 24 degrees by dawn at month end, Saturn is much fainter and a little lower but should also be visible. Venus is an evening object, very low, but very bright, in the twilight sky.

And, if anyone does have radio or radar equipment, June is the best time for daytime meteor showers.

The real highlight this month is the annular solar eclipse on 10th, visible from parts of E Canada, Greenland, Siberia and the North Pole. Because the Moon will be close to apogee at this time, it will appear smaller than average, not big enough to completely cover the Sun’s disc, so a thin ring - known as the Ring of Fire - remains visible round the Moon.

Because it is so far north, the path of annularity crosses many inaccessible, sparsely populated areas with only a 50% chance of cloud free sky. Add to that the current restrictions on travel and it is estimated that no more than 20,000 people will actually witness it.

In the UK we will (weather permitting) see a partial eclipse. From Manchester the Sun will be 25% obscured at the maximum, from London only 20%. Observers up in the Shetland Isles fare better, from there the Moon will cover nearly 40% of the Sun.

Warning: Do not look directly at the Sun, even when it is partly eclipsed. Special eclipse glasses, which cut out most of the light, are available and will enable you to see it safely.

Sunglasses are not dark enough, your eyes could still be damaged.


The Plough asterism in Ursa Major is still prominent, being overhead for much of the night, leaving Cassiopeia on the opposite side of the Pole Star, low in the northern sky. The Summer Triangle , consisting of Vega, Deneb and Altair, is now getting higher in the late evening, though Altair , in Aquila, is still quite low in the early part of the night. The beautiful double star Albireo , at the head of Cygnus the swan, is very well placed for observing. The Milky Way is now visible from dark sky sites, running across the sky through the Summer Triangle, passing almost overhead in the early hours. The bright orange red Arcturus is shining brightly high in the SW and, if you manage to find some dark skies not obscured by cloud, you should be able to see the rest of the kite shaped Bootes , with the semicircle of stars forming Corona Borealis just to the east of it. Another red giant, Antares in Scorpio is now visible low on the southern horizon.

Mercury : in Taurus, mag 3.0

Very difficult to see this month as it appears so close to the Sun. On 1st they both set around the same time and appear separated by 13 degrees. Mercury is at aphelion on 10th, 0.47AU from the Sun, separated by only 3 degrees and down to mag 6.1. The following day it reaches inferior conjunction, passing south of the Sun. On 30th, now at mag 1.0, it is still below the horizon as the sky brightens, rising at 03.47, about an hour before sunrise.

An evening object but very low in the sky after sunset. Despite its low altitude, because it is so bright, it should be visible to observers with a low, clear NW horizon. On 1st it is at 5 degrees as the sky darkens, setting at 00.53. It moves into Gemini on 3rd and on 12th at 06.30 the very thin crescent Moon is only 42’ from the planet. The pair are separated by 5 degrees after sunset on 11th but the Moon is lower than Venus and only 1% lit so is unlikely to be visible. On 12th the Moon, now at 4%, is higher and to the left, separated by about 6 degrees. Venus sets at 23.10, the Moon at 23.50. It is at perihelion on this day, at a distance of 0.72AU. It moves into Cancer on 26th, still only 6 degrees at dusk, and is no higher on 30th when it sets at 23.10.

Now low in the WNW at dusk. On 1st it is only 10 degrees as the sky darkens, setting at 00.35. It moves into Cancer on 9th, when it is only 6 degrees in the twilight. On 13th the 13% Moon passes 2 degrees 48’ directly north at 20.52. They are slightly closer, 2 degrees 46’, at 22.11 in civil twilight, when Mars will be 14 degrees above the horizon but too faint to be seen in the still bright sky. It will be down to 5 degrees when the sky darkens, setting at 00.06. From 22nd to 24th it passes through the Beehive Cluster very low in the WNW soon after sunset. On 30th, now at mag 1.8, it is on the horizon at dusk, setting at 23.21.

Jupiter : in Aquarius, mag - 2.5

Now becoming very prominent in the morning sky. On 1st the 54% Moon passes 4 degrees 21’ to the south at 12.56. The pair should be visible, separated by 7 degrees, at 03.00, down to 7 degrees by dawn when the planet will have reached 17 degrees. It begins retrograde motion (appearing to move from east to west) on 20th, when it rises soon after midnight and reaches 22 degrees in the SE by dawn. On 28th it is again close to the Moon, which is now at 76% and passes 4 degrees 27’ to the south at 19.41, on the morning of 29th they are separated by 5 degrees. On 30th Jupiter rises at 23.56, becomes visible around 1am and reaches 24 degrees in the SE by dawn.

Saturn : in Capricorn, mag 0.6

Slightly lower and much fainter than Jupiter but should be visible in the morning sky. On 1st it rises at 02.12, high enough to be seen by 3am and reaching 15 degrees in the SE as the sky brightens a little before 4am. On 27th the 87% Moon passes 4 degrees 01’ to the south at 10.26. On this day the planet should be visible from 01.00, when the Moon is 8 degrees to the SW, until dawn breaks at around 4am, with Saturn at 18 degrees in the SW. On 30th it rises at 23.14 and is high from 01.00, and visible until the sky gets too light at around 03.45. The planet’s north pole is currently tilted towards us by 18.3 degrees, so the rings show well when viewed through a scope.

Not visible this month. On 1st it is still 11 degrees below the horizon as the sky begins to brighten, rising at 03.38, just over an hour before the Sun. On 30th it rises at 01.46 in astro twilight but is still very low when dawn breaks.

Neptune : in Aquarius, mag 7.9

On 1st it is still just below the horizon at dawn, rising at 02.21. It begins retrograde motion on 25th, when it reaches 5 degrees in a fairly dark sky. On 30th it rises at 00.30 and only gets to 10 degrees before the sky brightens.

Pluto : in Sagittarius, mag 15

Still too low for imaging, despite rising at 00.38 on 1st and 22.43 on 30th. It is currently quite far south and, because it takes so long to orbit the Sun, it moves very slowly around the sky and, for Manchester observers, won’t get up to 20 degrees for another 40 years.

Haumea : in Bootes, mag 17.4

Best placed for imaging in early June. On 1st it is at 50 degrees in the west as the sky darkens around midnight, remaining high throughout astro twilight. By 30th it is only at 32 degrees as the sky fades before 1am, down to 23 degrees by dawn.

Makemake : in Coma Berenices, mag 17.2

On 1st it is at 49 degrees in the SW as the sky fades around midnight, remaining reasonably high until dawn. On 30th it is at 27 degrees in the west at 00.40 and only high enough for imaging for about half an hour.

Still below the horizon at dawn throughout June.

3 Juno : in Ophiuchus, mag 10.1

Reaches opposition on 6th, when it rises at 19.42 and culminates, 32 degrees in the south, at 01.22. High enough for imaging from 00.17 until dawn.

30 Urania : also in Ophiuchus, mag 11.1

Opposition on 14th. Much lower than Juno, despite being in the same constellation. Culminates at 01.17 but only reaches 10 degrees in the south.

Still nothing spectacular - or even fairly reasonable.

18P/Finlay is at perihelion on 18th, predicted mag 8.7, but is below the horizon during the hours of darkness for UK observers.

C/2020 T2 (Palomar) in Bootes, mag 10.1

Fainter but better positioned. On 1st it is high in the sky from midnight, reaching 52 degrees in the SW before the sky brightens. By the end of June it is only high for a very short time, 23 degrees in the west from 00.40 to 00.54.

Nothing spectacular this month, we have a few showers which may (or may not) provide a few meteors.

June Bootids : active June 22nd to July 2nd, peak June 27th.

ZHR given as variable - could be anything from zero to 30, very occasionally more - in 1998 a peak of around 100 was observed. Peak activity predicted for 11am on 27th. The radiant is circumpolar, highest at 22.00 so the shower is best seen after midnight when the sky is reasonably dark. They are very slow moving, long lasting meteors, parent comet 7P/Pons-Winnecke. The gibbous Moon will interfere, rising just before midnight on 27th.

June Lyrids : active 10th to 21st, peak 15th/16th ZHR 8.

This shower was first detected in 1966 and was active for a few years but hasn’t shown much activity recently. They were medium paced, mainly faint, blue coloured meteors with a few brighter ones which left trails. This shower isn’t mentioned in this year’s IMO calendar.

Beta Taurids : active June 5th to July 18th, peak June 28th, ZHR weak.

Again, not in the IMO calendar. This shower is notable only because the 1908 Tunguska meteor is thought to be associated with it.

Antihelion Source (ANT) active in early and late June, however the radiant, in Sagittarius, is very low. ZHR 2 to 4.

There is still some daytime activity - meteors detectable with radio or radar equipment.

Daytime Arietids : active May 14th to June 24th, peak June 7th, ZHR 30

The radiant of these is only 30 degrees west of the Sun, however a few meteors might be spotted visually in the morning twilight of 7th. Better seen from further south, where the sky is a little darker.

Zeta Perseids : active May 20th to July 5th, peak 9th or 13th (?)

This shower was first detected in 1947 by radio astronomers working at Jodrell Bank. Parent comet 2P/Encke

Other information is from various internet sources, including NASA, Britannica, Space Facts, Universe Today and, when all else fails,Wikipedia.

The night sky in May 2021

Sunrise 1st: 05.34 31st: 04.47

Sunset 1st: 20.39 31st: 21.26

1st: 23.27 to 02.43 31st: none

Astro darkness ends at 01.25 on 13th and that’s it until 30th July. Even astronomical twilight is getting shorter, by month end it only lasts from 23.38 to 02.36.

Day length 1st: 15:04:57 31st: 16:38:48

Full Moon: 26th at 12.15 (angular diameter 33’ 24”)

Lunar apogee: 11th at 22.55 (406511 Km, angular diameter 29’ 22”)

Lunar perigee: 26th at 02.53 (357309 Km, angular diameter 33’ 25”)

There will be a total lunar eclipse on 26th, visible from Australia, New Zealand, Antarctica, parts of New Guinea and most of the Pacific Ocean. Observers in Eastern Asia and Western Canada & USA will be able to see part of it.

This month’s full Moon occurs 9 hours 24’ after perigee so will appear slightly larger and brighter than average - a Supermoon.

The Old Farmers Almanac name for the May full Moon is the Flower Moon - for obvious reasons. Other names are the Corn Planting Moon, the Frog Moon and the Moon of Shedding Ponies. The Colonial American name was the Milk Moon and it was the Celtic Bright Moon or Dyan Moon (though some sources give that one for June). For the Chinese it was the Dragon Moon, to the Medieval English, the Hare Moon and the Neo Pagan name was the Grass Moon. Among the Indigenous American names are the Cherokee’s Planting Moon, the Choctaw’s Panther Moon and the Ojibwa tribe’s Budding Moon. The Dakota Sioux called it the Moon when Leaves are Green - quite mundane compared with some of their other names!

Still nothing spectacular predicted. Jupiter and Saturn’s positions in the morning sky are improving but, as they are in the most southerly part of the ecliptic, remain quite low. We’re losing Mars, by the end of May it is only 12 degrees above the horizon at dusk. Venus is also very low in the evening sky, Mercury is higher for most of the month, early to mid May is the best time this year to see it in the evening. The downside is that as it gets higher, it also gets fainter. There is one reasonable meteor shower but the radiant is so low that it is better seen from further south. However a few may be visible just before dawn.

From mid month we lose astronomical darkness but, as the Sun doesn’t get more than 18 degrees below the horizon, we may see some Noctilucent Clouds. These wispy silvery or bluish white clouds are formed when the Sun shines on ice crystals in the mesosphere, about 50 miles above the Earth, so high that they are still in daylight when the Sun has set for observers on the ground. They are most likely to be seen at latitudes between 50 and 70 degrees north. They also occur in the southern hemisphere but are not reported as often because there isn’t much land mass at the right latitudes.

As the sky darkens at the start of the month Lyra and Cygnus are rising in the north east, followed a couple of hours later by Aquila . In the later part of the night the Summer Triangle formed by Vega , Deneb and Altair , the brightest star in each of these three constellations, should be easily visible. By the end of the month Aquila will be above the horizon by around 11pm. The brightest part of the Milky Way visible to us in the UK runs through the Summer Triangle and down through Scutum and Sagittarius.

The Plough is still very high in the sky for most of the night, standing on its handle, so Cassiopeia , the W shaped 'Lady in the Chair', on the opposite side of the Pole Star is very low down in the north.

Bootes , the herdsman, is now riding high although only Arcturus , the brightest star in the celestial northern hemisphere, is above magnitude 2, so its kite asterism may not be easily visible in our light polluted skies. Arcturus is easy to find though - just follow the arc of the Plough's handle down to the south until you come to Arcturus. Carry on the arc a bit further and you come to the star Spica , the brightest star in Virgo .

At this time of year when you look up to the south you are looking out of the plane of our Milky Way galaxy instead of along it like you do in winter and summer, so there aren't many bright stars, open star clusters and nebulae. However, if you've got a telescope this is a good time of year to hunt down globular clusters like M13, the Great Globular Cluster in Hercules , and faint galaxies like the many galaxies lying in the bowl of Virgo and into Coma Berenices .

Early to mid May is the best time this year to see it in the evening twilight. On 1st it is 6 degrees above the horizon as the sky darkens, setting at 22.02. It moves into Taurus on 2nd and the following day should be visible for a few minutes, soon after 9pm, when it is 8 degrees in the NW. On 13th the thin crescent Moon passes 2 degrees 08’ to the south at 18.58, the pair are separated by 2 degrees 40’ at 21.40 when Mercury is 9 degrees above the horizon. It reaches its highest point in the evening sky on 15th, when it will be at 15 degrees at sunset but down to 9 degrees by the time the sky darkens, and considerably fainter at mag 0.1. It is at greatest eastern elongation on 17th, when it appears 22 degrees from the Sun but still only 9 degrees above the horizon at dusk. On 29th, now faded to mag 2.3, it is just 25’ south of Venus at 06.34. The pair are quite close on the evenings of 28th, about 30’, and 29th, about 1 degree. However they will be very difficult to spot, almost on the horizon in twilight. On 31st Mercury appears only 14 degrees from the Sun, setting at 22.35.

Not visible at the start of May. On 1st it is only 2 degrees above the horizon at dusk, setting at 21.25. It moves into Taurus on 4th and on 12th the very thin, relatively small (29’ 24” - only a day past apogee) crescent Moon passes 42’ to the south at 23.03. The separation at 21.00 is about 2 degrees but Venus is only 3 degrees above the NW horizon as the sky darkens, setting at 22.04, ten minutes after the Moon. On 28th Venus is close to Mercury and might be visible, 5 degrees above the horizon, in twilight. Mercury, much fainter, is unlikely to be seen.

REMEMBER: if trying to see the pair using binoculars, wait until the Sun has fully set.

On 31st Venus is still only 5 degrees above the horizon at dusk, setting at 22.52.

An early evening object in the first part of the month. On 1st it should become visible around 21.45, when it is 29 degrees above the western horizon. By midnight it will be too low to be seen easily, setting at 01.31. On the nights of 15th and 16th the crescent Moon passes north of the planet, closest at 05.15 on 16th. As the sky darkens on 15th, the separation is around 5 degrees, slightly more the following day when the Moon is to the east. By the end of May, Mars will be difficult to spot, on 31st it is only 11 degrees above the horizon at dusk, setting at 00.35.

Jupiter : in Aquarius, mag -2.2

Now becoming more prominent in the pre-dawn sky. On 1st it rises at 03.41 and reaches 10 degrees in the SE by 04.45. On the morning of 5th the 35% Moon is just under 6 degrees SSE of the planet in the morning twilight. They are closest, 4 degrees 21’, at 00.55 while still below the horizon. Jupiter now reaches 11 degrees before the sky brightens. It gets higher as the month progresses, on 31st it is visible from 3am and reaches 17 degrees in the SE by dawn.

Saturn : in Capricorn, mag 0.7

Another pre dawn object but much fainter and harder to see than big brother Jupiter. On 1st it rises soon after 3am and reaches 9 degrees by dawn. On 3rd the 45% Moon passes 4 degrees 09’ to the south at 17.58. On the morning of 3rd they are separated by 8 degrees at 5am, with Saturn reaching 10 degrees in relative darkness. The pair are slightly closer, 6 degrees, on the morning of 4th with Jupiter about 15 degrees to the left, so the three form a triangle. On 23rd Saturn appears to stand still for a short while before changing direction and moving from east to west against the background stars - retrograde motion. On 31st it rises at 01.16 and is again close to the Moon, which passes 4 degrees 10’ south at 02.18 while the planet is still too low to be seen, becoming visible around 3am, when it will be 15 degrees in the east. They are closest, 4 degrees 03’, soon after 4am as the sky begins to brighten.

Not visible this month following solar conjunction at the end of April. On 1st it is only 1 degree from the Sun. By month end it is still 10 degrees below the horizon by dawn, rising about an hour before the Sun.

Neptune : in Aquarius, mag 7.9

Also not visible in May. It is below the horizon at dawn throughout the month.

Another one which appears very close to the Sun this month. On 1st the separation is 15 degrees. It moves into Cetus on 13th and on 31st is still below the horizon at dawn, rising only half an hour before the Sun.

Pluto : in Sagittarius, mag 15.4

Still much too low in the morning sky for imaging or telescopic observation.

Haumea : in Bootes, mag 17.3. Makemake : in Corona Borealis, mag 17.2.

Both high in the sky for most of the night. If any experienced astrophotographers fancy having a try at imaging these, exact positions can be found in in-the-sky - details at the end of these notes.

It is too close to the Sun for imaging, following April’s solar conjunction.

No bright comets again this month.

C/2020 R4 (ATLAS) in Canes Venatici

Predicted to end April at around mag 8.4, but failed to live up to expectations. Now expected to start May at around mag 10, but is still above the horizon for most of the night. On 1st it reaches its highest point, 69 degrees, at 00.35. It fades quite rapidly and gets lower in the sky as the month progresses, on 7th, down to mag 10.9, it moves into Coma Berenices and culminates at 22.48, soon after the sky darkens enough for it to be seen. It spends 12th & 13th in Ursa Major then goes into Leo for the rest of May. On 31st, predicted mag now 13.8, it is at 32 degrees in the west at dusk, high for just over an hour and setting soon after qam.

Eta Aquarids : active April 19th to May 28th, peak around 3am on 6th, but with good rates for about a week centred on this date. ZHR is given as 50 but the radiant is so low that the shower is much better seen from the southern hemisphere. From the Manchester area the best that we can expect is about 10. They are fast moving meteors, often leaving persistent trails, and are best seen between 02.30 and dawn. The waxing crescent Moon doesn’t rise until 04.25 on 6th, so won’t interfere. It is one of 2 showers associated with Comet 1P/Halley.

Eta Lyrids : active May 3rd to 14th, peak 8th, ZHR 3

These are medium speed meteors, parent comet C/1983 H1 (IRAS-Araki-Alcock)

The Antihelion Source (ANT) has a ZHR of 2 - 4 in May. The radiant moves through northern Scorpio and into Ophiuchus during the month.

May, especially the later part of the month, is good for daytime showers, which have a radiant so close to the Sun that they can’t be observed visually. They are detectable only with radio or radar equipment.

Epsilon Arietids : active April 24th to May 7th, peak May 9th. Rates given as low (numbers not given for any of these)

May Arietids : May 4th to June 6th, peak May 16th. Again rates are low.

Omicron Cetids : active May 5th to June 2nd, peak May 20th. This one is slightly better - rates given as medium.

More active are the daytime Arietids , beginning May 14th but not peaking until mid June. Rates for this shower are expected to be high.

Other information is from various internet sources, including NASA, Britannica, Space Facts, Universe Today and, when all else fails,Wikipedia.

6 Stone-cold Facts About the Arctic Circle

We all depend on sunlight, but unless you live at the equator, you won't get the same amount of it every day. Ours is a tilted world, friends. Like all the planets in this solar system, Earth rotates around an axis, an imaginary line between its North and South poles. At the same time, it orbits the sun, finishing a new lap every 365.25 days.

That cosmic ballet is an intricate dance. Relative to its pathway around the sun, Earth's axis is tilted at a 23.5-degree angle. If it weren't for that helpful tilt, seasons as we know them wouldn't exist. The skewed axis is also responsible for one of the world's most astonishing places: The Arctic Circle.

Geographers define the circle as everything at or above 66 degrees and 34 minutes north latitude. (Put simply that means the exact dividing line falls between the 66th and 67th parallels in Earth's Northern Hemisphere.)

It's a region marked by strange hours. Throughout this area, the center of the sun never climbs above the horizon during the winter solstice — the shortest day of the year. Here, the skies can be dark at high noon or sunny at midnight. Yet life persists. The Arctic Circle encompasses 4 percent of the global surface. And for hundreds of thousands of people, it's also home sweet home.

1. Eight Countries Own Land There

Jetting into the Arctic Ocean, Alaska's Point Barrow is the northernmost tip of the United States. Of course, Alaska's not the only place that penetrates the Arctic Circle. Large portions of Canada, Russia, Norway, Finland and Sweden also fall within the Arctic Circle's borders. So does the majority of Greenland, a territory held by the Kingdom of Denmark. (Sorry Mr. Trump: The Danish won't sell it.) Last, but not least, Grimsey Island — an Icelandic holding — is split by the circle.

2. Murmansk, Russia Is the Biggest City

Around 295,000 people live in Murmansk, a port city founded in 1916 at the height of World War I. One of its Soviet-era landmarks, the 236-foot (72-meter) Arktika Hotel, is the tallest building north of the Arctic Circle.

The region's second-largest city is Russian, too. Norilsk, a community of some 179,554 souls, is famous for its mining operations and the historic Nord Kamal Mosque. Outside of Russia, the Arctic Circle's most populous municipality is Tromsø, Norway, which boasts the world's northernmost university.

3. It Doesn't Plunge Into Total Darkness

Even when the sun's out of view, the twilight it produces can still illuminate the skies. And guess what? Many communities above the Arctic Circle receive plenty of twilight in the darkest stretch of the year. Consider Utqiaġvik, a city in far north Alaska. For 65 days each winter, the sun doesn't rise there. Yet during this same period, Utqiaġvik gets three to six hours of daily twilight.

But maybe that's not good enough for you. Maybe you're an Arctic tourist who'd like to experience twilight-free, star-studded darkness for days on end. (Hey, we're not judging.) That's a phenomenon called "astronomical polar night." And it's only known to take place at latitudes higher than 88 degrees 33 minutes north, far above cities like Utqiaġvik — or any human settlements for that matter. Where it occurs, the astronomical polar night lasts for roughly 11 weeks, not half the year as some sources claim.

Watch the video: was TWILIGHT always this CRINGEY?? re-watching marathon (June 2022).


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