Astronomy

I need to study space, planets and black holes, how do I study them on my own

I need to study space, planets and black holes, how do I study them on my own

I need to study space, planets and black holes, how do I study them on my own, knowing that I am an Arab and I do not know English. I use translation applications. I speak with you. Can you help me with a site or YouTube channel? I don't want books


  1. I am sorry to say, but the best resources are still books. If it is really a no-go, read further. It is very likely, that you can find and buy astronomy books on Arabic on the Internet. First start with popular science books. Buy multiple books. To learn something, books are still somehow far better than the Internet.
  2. Check the Arabic wikipedia, like this article.
  3. Just think freely. Imagine a question, anything, like "How far are we from the edge of Universe?"1. My experiences is that the resources on my first language (far lesser amount of speakers than Arabic) are significantly lesser, but they exist. Enter the question on Arabic into the google search.
  4. Any time if something is not clear, come here and ask.

1It is actually a bad question, but you don't know yet, why. Here is the answer, why. This was only an example question.


I need to study space, planets and black holes, how do I study them on my own - Astronomy

The School of Earth and Space Exploration is home to one of the world's leading centers for observational and theoretical research in astronomy and astrophysics. Our research interests range from the Solar System to stars, to the Milky Way, to the most distant galaxies in the Universe, and from cosmology to fundamental questions of astrobiology.

In addition to the school's in-house laboratories for state-of-the-art instrumentation, we have access to state-of-the-art facilities including world-class telescopes and instrumentation for the sub-mm, radio, infrared, and optical as well as extensive computing facilities, including in-house parallel supercomputers.

ASU is also a founder institution of the Giant Magellan Telescope (GMT), a next-generation ground-based telescope that promises to revolutionize our understanding and view of the universe. The GMT is poised to enable breakthrough discoveries in cosmology, the study of black holes, dark matter, dark energy, and the search for life beyond our solar system.

Search the tabs below to learn more about our cosmology, astronomy, and astrophysics faculty, labs and research groups.

Computational Astrophysics


Benjamin Banneker

Benjamin Banneker (November 9, 1731 – October 19, 1806) was a free Black American mathematician, author, surveyor, landowner, and farmer heralded as the first Black astronomer in the United States. Utilizing his knowledge of astronomy and mathematics, he authored one of the first series of almanacs accurately predicting the positions of the Sun, the Moon, and the planets. In his late teens, he built a wooden pocket watch that kept precise time for over 40 years until it was destroyed in a fire. In 1788, he accurately predicted a solar eclipse that occurred in 1789. Working alongside Major Andrew Ellicott, he completed the survey setting the original borders of the District of Columbia in 1791.

Born a freeman on November 9, 1731, in Baltimore County, Maryland, Banneker was raised on a farm he would eventually inherit from his father. Largely self-educated, he read voraciously about astronomy, mathematics, and history from borrowed books. Any formal education he might have received is believed to have come in a Quaker school near his home.

Though never enslaved himself, Banneker was vocal in his support of abolition. In 1791, he began corresponding with Thomas Jefferson appealing for Jefferson’s assistance in ending the practice of enslavement and securing racial equality for Black Americans. “The time, it is hoped is not very remote, when those ill-fated people, dwelling in this land of freedom, shall commence a participation with the white inhabitants, in the blessings of liberty and experience the kindly protection of government, for the essential rights of human nature,” he wrote.


I need to study space, planets and black holes, how do I study them on my own - Astronomy

This unit is ©Copyright 2004 by Cindy Downes. All rights reserved. Permission is given to homeschooling parents to use these units free of charge in their own homeschool only. These units may not be reprinted in any other form, for any other purpose (commercial or otherwise) without permission from Cindy Downes. Contact her at [email protected]

This unit is designed to be completed in twelve weeks, completing two, 1 - 2 hour lessons per week for a total of 24 lessons however, you can customize it to any length, depending upon how much material you cover and how long you take to cover it . Read over General Directions for Cindy's Unit Studies for information on how to teach the unit.

  • Creation Science Video Lending Library-Free by mail. Dinosaurs, Creation, Astronomy, Geology, http://www.creationism.org/library/index.htm
  • TCM Space Websites. http://www.teachercreated.com/books/3076/
  • Free, printable space sticker chart: http://www.preschoolprintables.com/schart/schartspace.shtml
  • Planets Thematic Unit, Primary, grades 1-4+
  • Considering God's Creation Student Workbook, 5th Edition, Christian based, pages 7-27, ISBN 1931292027. gr 2-6
  • Exploring Space, Scienceworks for Kids, ISBN 1557996822. Gr 1-3+
  • Exploring the Planets , ISBN 059068732. Includes a pull-out, color poster. Create a martian landscape with playdough, make a planet mobile, create a mini book about the solar system and more. Gr. 3-6+
Lesson 1 -4: Introduction to Our Solar System
  • There’s No Place Like Space! All About Our Solar System (The Cat in the Hat Learning Library series) by Tish Rabe. 42pgs., color, ISBN: 0679891153. K-3+
  • The Planets in Our Solar System by Franklyn Branley. (Let's Read and Find Out Science) ISBN 006445178X. PreK-4+

2. Complete the following activities in Planets Thematic Unit , Primary, 1-4+

  • Complete a Daily Writing Activity, pg. 20-21
  • Solar System Booklet, Pg. 7, #6, pg 30.
  • Miniature Solar System, pg. 51 (supplies needed)
  • Solar System Cookies, pg. 57
  • Newton's Workshop: As the World Spins (The Solar System). Grandpa Newton helps Trisha learn about the solar system and the works of Copernicus, Kepler, and Galileo and how it all fits together within the framework of the Bible. 28 minutes.
  • Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/. (The Solar System) K-6
  • Solar System Simulator: http://space.jpl.nasa.gov/. View actual photos of planets in space. All ages.
  • Puzzles: http://www.EnchantedLearning.com/subjects/astronomy/ (Classroom Activities - Interactive Puzzles - Solar System), 1-6
  • Zoom Astronomy: http://www.EnchantedLearning.com/crafts/astronomy/. (Solar System) PreK-6
  • Play Solar System Switch-a-Roo: http://spaceplace.nasa.gov/en/kids/sse_flipflop.shtml

5. Other Reading Suggestions:

  • My Book of Space, Kingfisher, 2001, color, 48pgs, ISBN 0753453991. K-4+
  • Postcards from Pluto: A Tour of the Solar System by Loreen Leedy. ISBN 0823410005. K-4
  • Composition: Astronomy theme paper
  • Powerpoint Simple Projects, Intermediate, pg. 57-61, Touring the Solar System, 3-6+
  • Inflatable Solar System SetTeach size and distance relationships of planets, the moon and the sun. Learn rotation, revolution and orbit through class activities or demonstrations using this realistic looking set. Includes 36" Sun and proportionate planets and moon with sizes ranging from 8" to 22". Also includes a foot pump, Teacher's Activity Guide and hooks for easy hanging. Deflate for easy storage.
Lesson 5 - 8: Stars, Calendars, Time, Constellations
  • Night Sky by Robin Kerrod. ISBN 0739828150. 32 pages. color. Describes what stars and constellations can be seen in the night sky and provides instructions for finding them.
  • The Sky Is Full of Stars (Let's-Read-and-Find-Out Science 2) by Franklyn M. Branley. ISBN 0064450023. K-4+
  • What Makes Day and Night by Franklyn Branley. 32 pgs, color. ISBN 0064450503. K-3+
  • The Reasons for Seasons by Gail Gibbons. ISBN 0823412385. K-3+

2. Complete the following activities in Planets Thematic Unit, Primary, 1-4+

  • Complete a Daily Writing Activity, pg. 20-21
  • Hours in a Day, pg 28
  • Happy Birthday to You, math, pg. 29
  • What Makes a Day?, pg. 37
  • Shadow Clock, pg. 38-39
  • It’s in the Stars, pg. 48
  • Stars in a Box, pg. 53-54

6. Other Reading Suggestions:

  • The Big Dipper . by Franklyn Branley. ISBN 0064451003. 32 pgs, color. K-6
  • Follow the Drinking Gourd by F. N. Monjo. Following the stars on the Underground Railroad during the Civil War. Also a video or cassette available. 48 pgs, color. ISBN 0064440427. Easy Reader.
  • Mouse, Mole, and the Falling Star by A.H. Benjamin. unpaged, color. The pursuit of a falling star and its fabulous reward almost breaks up the good friendship between Mole and Mouse. ISBN 1854307827. PreK-1
  • Magic School Bus Greatest Adventures. When Ms. Frizzle's class gets lost while on a field trip in outer space, the kids explores our solar system, then the class discovers that even the tiniest living things can have big effects as they visit the mini-world of microbes in a pickle.
  • Powerpoint Simple Projects, Challenging, 6-8+ pg. 70-77, Learning About the Constellations
  • Using The Night Sky (ISBN 0961320753), practice identifying the constellations in your area.
  • Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/. (Stars) K-6+
  • Zoom Astronomy: http://www.EnchantedLearning.com/themes/stars.shtml (Stars craft activities), PreK-6
  • Star Child. For Young Astronomers. http://starchild.gsfc.nasa.gov/docs/StarChild/StarChild.html. 1-6+
L esson 9 - 10 : Space Exploration
  • Floating in Space (Let's Read and Find Out Science) by Franklyn Branley. ISBN 0064451429. PreK-4+
  • Footprints on the Moon by Alexandra Sly, color, Easy read, lots of pictures, ISBN 1570914095. 32 pgs, color. 1-6
  • Life of an Astronaut by Niki Walker. Excellent. ISBN 0865056935. 1-6

Complete the following activities in Planets Thematic Unit, Primary, 1-4+

  • Complete a Daily Writing Activity, pg. 20-21
  • Space Journey Application, pg. 24
  • Moon Landing Booklet, pg. 40-42
  • Voyager Space Probes booklet, pg. 43-45
  • Build a rocket using Meteor Rocket Kit. ISBN B00000IS7I.
  • Composition: A Report on an Astronaut, pg. 61, Forms for Report Writing
  • Sneak peak at what’s happening at Kennedy Space Center today. Live. http://science.ksc.nasa.gov/shuttle/countdown/video/video.html
  • Dot-to-Dot Spacecraft: http://spaceplace.nasa.gov/en/kids/ds1dots.shtml

Other Reading Suggestions:

  • Apollo Moonwalks by Gregory Vogt. 48 pgs, color. ISBN 0766013065. Gr 1-6
  • Astronauts (True Book) by Allison Lassieur. 47 pgs. color. ISBN 0516271857. Gr 1-6
  • Best Book of Spaceships by Ian Graham, 1998, color, 32 pgs. ISBN 0753451336. K-4+
  • Curious George and the Rocket by H. A. Rey (For fun!), ISBN 0618120696. K-2
  • John Glenn, Young Astronaut, Childhood of Famous Americans, ISBN 0689833970. 192 pages. 2+
  • Neil Armstrong, Young Flyer, Childhood of Famous Americans , ISBN 0689809956. 192 pages. 2+
  • Neil Armstrong by Shannon Zemlicka, 48 pg. some color, Excellent. ISBN 0822515636. 2-6
  • Astronomy for Kids: http://dustbunny.com/afk/index.html. 3-6+
  • Fun Things - Rocket Craft, Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/, PreK-6
  • Space Explorers - Zoom Astronomy: http://www.EnchantedLearning.com/crafts/astronomy/. PreK-6
Lesson 11 - 12, Earth
  • Earth (Solar System series) by Lynda Sorensen. 24 pgs., ISBN 0865932751. K-3
  • Earth (Our Planet in Space) by Simon Seymour. ISBN 0689835620.

Complete the following activities in Planets Thematic Unit, Primary, 1-4+ (G)

  • Your Weight on Other Worlds. http://www.exploratorium.edu/ronh/weight/index.html. 1-8+
  • Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/. (Earth) K-6+
  • Puzzles: http://www.EnchantedLearning.com/subjects/astronomy/ (Classroom Activities - Interactive Puzzles - Earth), 1-6
  • Play Earth Watcher on The Space Place: http://spaceplace.nasa.gov/en/kids/misr_xword/misr_xword1.shtml
Lesson 13 - 14 Moon
  • What the Moon is Like by Franklyn Branley. 31 pgs. color. (J 559.9 B73w 1986), K-4+
  • Eclipse: Darkness in Daytime by Franklyn M. Branley. 32 pgs., color. K-4+

Complete the following activities in Planets Thematic Unit, Primary, 1-4+

  • Complete a Daily Writing Activity, pg. 20-21
  • Moon—Complete the following activities in Investigating Science: Solar System
  • By the Light of the Moon, pg. 24 (ball, flashlight, mirror)
  • Man in the Moon, pg. 25 (supplies)
  • Great Disappearing Act, pg. 26 (ball, flashlight, sticky note)
  • Lunar Illusions, pg. 27
  • One Small Step for Man, pg. 27

Other Reading Suggestions:

Lesson 15 - 16, Sun

Complete the following activities in Planets Thematic Unit, Primary, 1-4+

  • Complete a Daily Writing Activity, pg. 20-21
  • Directions from the Sun, pg. 37
  • Solar Shadows, pg. 37
  • Race to the Sun, pg. 49

Other Reading Suggestions:

  • Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/. (Sun) K-6+
  • Puzzles: http://www.EnchantedLearning.com/subjects/astronomy/ (Classroom Activities - Interactive Puzzles - Sun), 1-6
  • Zoom Astronomy: http://www.EnchantedLearning.com/crafts/astronomy/. (Paper Plate Sun) PreK-6
Lesson 17 - 20 , Planets

2. Complete the following activities in Planets Thematic Unit, Primary, 1-4+ (G)

  • Order the Planets, pg. 25
  • Complete a Daily Writing Activity, pg. 20-21
  • What’s in a Name, pg. 22
  • Celestial Similes, pg. 23
  • Riddle Math, pg. 26
  • Planet Chart, pg. 17
  • Research a planet, Pg 7,#3, #4, pg. 36, 69
  • How Much Do You Weigh, pg. 46
  • Is Pluto a Planet? pg. 47

3. Complete page 19, Solar System Detective, for each planet studied, Considering God's Creation Student Workbook, 5th Edition .

Other Reading Suggestions:

  • Touchdown Mars: ABC Adventure by Peggy Wethered, 32 pgs, A fun book! ISBN 0399232141, K-2+
  • Planets (Solar System series) by Lynda Sorensen. 24pgs., ISBN 0865932743, K-3
  • Play Blast Off on a Mars Adventure on The Space Place: http://spaceplace.nasa.gov/en/kids/mars_rocket.shtml
  • Music: Listen to The Planets, suite for orchestra & female chorus, CD by Gustav Holst.
  • Planet Simulation Activity. Collect the following objects. Sun-any ball, diameter 8.00 inches, Mercury-a pinhead, diameter 0.03 inch, Venus-a peppercorn, diameter 0.08 inch, Earth-a second peppercorn, Mars-a second pinhead, Jupiter-a chestnut or a pecan, diameter 0.90 inch, Saturn-a hazelnut or an acorn, diameter 0.70 inch, Uranus-a peanut or coffeebean, diameter 0.30 inch, Neptune-a second peanut or coffeebean, Pluto- a third pinhead (or smaller, since Pluto is the smallest planet) Ask: "How much space do we need to make it?" To arrive at the answer, we have to introduce scale. This peppercorn is the Earth we live on. The Earth is eight thousand miles wide! The peppercorn is eight hundredth of an inch wide. What about the Sun? It is eight hundred thousand miles wide. The ball representing it is eight inches wide. So, one inch in the model represents a hundred thousand miles in reality. This means that one yard (36 inches) represents 3,600,000 miles. Take a pace: this distance across the floor is an enormous space-journey called "three million six hundred thousand miles." Now, what is the distance between the Earth and the Sun? It is 93 million miles. In the model, this will be 26 yards. It will be necessary to go outside. From website: http://www.noao.edu/education/peppercorn/pcmain.html
  • Our Solar System : The Inner Planets. Takes a fun and informative voyage aboard a homemade spacecraft to the inner planets in our solar system. Interesting facts about each planet are presented, such as size, composition, relative position in the solar system, gravity, and temperature. 26 min. (Check your library.)
  • Our Solar System: The Outer Planets. Takes a fun and informative voyage aboard a homemade spacecraft to the outer planets in our solar system. Interesting facts about each planet are presented, such as size, composition, relative position in the solar system, gravity, and temperature. (Check your library.) 26 min.
  • Welcome to the Planets. Cool photos. http://pds.jpl.nasa.gov/planets/. All ages.
  • Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/. (The Planets) K-6+
  • Puzzles: http://www.EnchantedLearning.com/subjects/astronomy/ (Classroom Activities - Interactive Puzzles - click on various planets), 1-6
Lesson 21 - 22 Comets, Meteors, Asteroids
  • Meteor by Patricia Polacco (J Fiction), 32 pgs. A fun book! Color illus. ISBN 0698114108. K-6.
  • Comets by Frankly M. Branley. 32 pgs. color, Let’s Read and Find Out Science, ISBN 0064450171, K-6
  • Comets, Asteroids, and Meteors by Robin Birch. 32 pgs. ISBN 0791069737. K-4+

Complete the following activities in Planets Thematic Unit, Primary, 1-4+ (G)

  • Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/. (Small Bodies-Asteroids, comets, meteors) K-6+
  • Puzzles: http://www.EnchantedLearning.com/subjects/astronomy/ (Classroom Activities - Interactive Puzzles - Comets, Asteroids), 1-6
  • Play Tales of Wonder on The Space Place: http://spaceplace.nasa.gov/en/kids/stardust/index.shtml
Lesson 23 Galaxies, Black holes, Other solar systems? UFOs? ETs?

Complete the following activities in Planets Thematic Unit, Primary, 1-4+ (G)

  • Milky Way Galaxy project, pg. 7, #1, pg. 50
  • Complete a Daily Writing Activity, pg. 20-21
  • Space creature pencil can, pg. 55

3. Choose an astronomer to research. Complete page 8, Considering God's Creation Student Workbook, 5th Edition, Scientist Detective, for your report on the scientist.

Lesson 24: Review
  • IPlanetarium: http://www.kidscom.com/adventure/iplanet/iplanet.html. 1-6
  • Zoom Astronomy: http://www.EnchantedLearning.com/subjects/astronomy/. (Fun Things) K-6+
  • Solar System Tutorial: http://www.EnchantedLearning.com/subjects/astronomy/ (Classroom Activities-Solar System Tutorial), 1-6
  • Quizzes: http://www.EnchantedLearning.com/subjects/astronomy/ (Classroom Activities- Astronomy Quizzes), 1-6
  • Field Trip: Visit a planetarium/observatory.
  • Complete page 80 in Exploring Space, Gr 1-3.
  • Play other Games on the Space Place. http://spaceplace.jpl.nasa.gov/index.shtml

Be sure to enter these topics on your copy of The Checklist.


Astrology and Star Constellations

8. Astrological Forecasting for Everyone

This course tries to make the ideas of astrology and astrological forecasting as simple as possible. Through unintimidating and simplistic language, this course will teach you the fundamentals of astrology, such as signs, houses, and planets. The goal of the course is to teach you enough information to write and read your own forecasts by the end. The course slowly builds upon itself to assure that you are not lost or confused along your learning path.

If you want to learn about the components of astrology and astrological forecasting, this course will be a great guide for you to get started.

  • Level: Beginners
  • Duration: 6.5 hours of video, 1 article, 146 resources
  • Start Date: Open anytime, accessible after enrollment
  • Reviews: 36 reviews
  • Rating: 4.7

9. Greek Mythology in Astronomy

This course connects the constellations in the night sky to their mythical counterparts in Greek mythology. Many of the constellations come from stories found in Greek mythology and literature. Taking the stories of Orion (the great hunter), Perseus, Orpheus, and Phaethon, the course explores how the constellations remind us of the great Greek legends, traditions, and stories developed in Ancient Greece.

This course is great for those more interested in the stories behind the constellations rather than the astronomy of the stars.

  • Level: Beginners
  • Duration: 35 minutes of video
  • Start Date: Open anytime, accessible after enrollment
  • Reviews: 4 reviews
  • Rating: 3.3

This Physicist Says She Has Proof Black Holes Simply Don't Exist

Scientists have lots of bizarre theories about black holes. Black holes gobble up everything that gets too close, even light. They can cause time to slow. They contain entire universes.

But here's something about black holes you might not have heard: they simply don't exist.

At least that's the contention of Dr. Laura Mersini-Houghton, a theoretical physicist at the University of North Carolina at Chapel Hill. In a new paper submitted to the non-peer-reviewed online research paper repository ArXiv, she offers what she calls proof that it's mathematically impossible for black holes ever to form.

The paper was greeted with skepticism by other physicists, and Mersini-Houghton herself admitted her finding was hard to swallow.

"I'm still not over the shock," she said in a written statement issued by the university. "We've been studying this problem for more than 50 years and this solution gives us a lot to think about."

The paper suggests a possible resolution of the so-called "black hole information loss paradox," in which Einstein's theory of relativity predicts that black holes should form but quantum theory says no "information" can ever permanently disappear from the universe.

In the conventional view, a black hole forms when a dying star collapses under the force of its own gravity to become a single point in space. The gravity within the region surrounding this so-called singularity is so intense that not even light can escape--hence the term black hole.

But according to Mersini-Houghton, a collapsing star sheds mass as it shrinks--so no black hole ever forms. Instead, as she and her collaborator--University of Toronto computational relativity expert Dr. Harald Pfeiffer--write in their paper, the star "stops collapsing at a finite radius. and its core explodes."

Mersini-Houghton told The Huffington Post in an email that by doing away with black holes, her explanation also eliminates a lot of the strange, almost incomprehensible properties long ascribed to them:

"Things were up for grab before when we thought there were singularities but did not know what they are or what happens near them. That led to a whole lot of speculation about singularities pinching off spacetime and making holes in the universe, and swallowing all the information about our universe. Now Harald and I have shown that since there are no singularities then we are back in the land of certainty as far as stars in our universe are concerned. We can study them with physics we trust and can follow their evolution through all the stages, with no mystery of incomprehensible exotic objects such as singularities involved."

If Mersini-Houghton is correct, long-held theories about the origin of the universe may need revising. But not everyone is buying her ideas.

"I'm not convinced," Dr. Max Tegmark, a cosmologist and professor of physics at MIT, told The Huffington Post in an email. "It's great to see numerical calculations being done, but the results disagree with many published findings, and this might be because of incorrect assumptions.

"Also," Tegmark said in the email, "one can't claim 'black holes don't exist' without first explaining all the observational evidence we have for black holes."

Tegmark's assessment was echoed by that of Dr. David Garfinkle, a professor of physics at Oakland University in Rochester, Michigan and an expert on singularities and gravitational fields. In an email to The Huffington Post, he called the paper "interesting" but added:

"We don't know enough about. the singularity to say whether [Messini-Houghton's] picture is correct. Even if it is correct, it is very misleading to describe it as showing that 'black holes don't exist.' There is a lot of astronomical evidence for objects that behave just like the black holes predicted by Einstein's theory of relativity."

Mersini-Houghton told HuffPost that a previous paper on the same topic had gotten "great reviews," and the new one had generated "lots of questions from colleagues who are interested to understand our findings."


Mini Black Holes Zip Through Earth Every Day?

Black holes smaller than atoms pass unnoticed through planet, study suggests.

Like cosmic ghosts, miniature black holes may be zipping harmlessly through Earth on a daily basis, a new study suggests.

The new theory rebuts doomsday scenarios in which powerful atom-smashing machines such as the Large Hadron Collider spawn black holes that swallow the planet.

Instead, the study authors think that tiny black holes would behave very differently from their larger brethren in deep space, called astrophysical or stellar-mass black holes.

Despite having roughly the mass of a thousand sedans, a mini black hole would be smaller than an atom. At that size the black hole wouldn't swallow much matter and would instead mostly trap atoms and some larger molecules into circling orbits—in much the same way that protons in atoms capture and bind electrons.

The study authors therefore call mini black holes with orbiting material Gravitational Equivalents of an Atom, or GEAs.

"GEAs would not cause any damage to you," said study co-author Aaron VanDevender, a researcher at biotechnology firm Halcyon Molecular in Redwood City, California. "An atom bound to the GEA might get stripped off and collide into you, but you wouldn't notice. It's a very small amount of energy."

Universe Seeded With Mini Black Holes

Stellar-mass black holes are thought to form when giant, dying stars collapse, leaving corpses that are so dense not even light can escape their gravitational pull.

Scientists think multiple stellar-mass black holes can merge to form supermassive black holes, which are found in the hearts of large galaxies, including our own Milky Way.

While we can't see a black hole itself, scientists can see the light from superheated material spiraling into the black hole, creating what's known as an accretion disk.

Meanwhile, theory predicts that an abundance of tiny black holes were created shortly after the beginning of the universe, as very dense matter was expanding and cooling. (Related: "Immaculate Black Holes Found Near Universe's Conception.")

This primordial matter was not evenly distributed throughout the early cosmos, so some regions of space were denser than others, VanDevender said.

"Because of random variations in the density [of matter], some of those chunks happened to form black holes in the beginning," he said.

According to physicist Stephen Hawking, smaller black holes should actually lose mass in the form of radiation and should ultimately evaporate.

But this so-called Hawking radiation has never been observed, so the new study assumes that tiny primordial black holes continue to exist throughout the universe.

Based on their calculations, VanDevender and his father, J. Pace VanDevender of Sandia National Laboratories in Albuquerque, New Mexico, estimate that one or two of these mini black holes passes through Earth every day.

Mini Black Holes Too Small to Devour Much

According to the new study, published online this month on arXiv.org, the main behavioral difference between small and large black holes is what happens at the so-called event horizon, the closest an object can get to a black hole before it becomes impossible to escape.

The larger and more massive a black hole is, the wider its event horizon.

"We think of gravity as always being an attractive force, and in the case of very large black holes, that attraction is so great that it's going to pull everything into it," Aaron VanDevender said. "But in those cases, you're pulling it into a very large event horizon. You have a very large space to absorb things into."

By contrast, the event horizon for a mini black hole is smaller even than the diameter of an atom. This means that a mini black hole can zip through an entire planet and still have very little chance of veering close enough to an atom for it to pass the event horizon.

When a mini black hole does attract a particle, it will most likely circle the black hole far from the event horizon and not be absorbed, the theory states.

"In the GEA case, atoms don't fall into the event horizon for the same reason that electrons don't fall into a nucleus," VanDevender explained.

According to quantum mechanics, electrons don't have well-defined orbits around atoms, as the planets do around the sun. Instead the particles exist in a kind of cloud of possibilities around the nucleus. The most stable—and thus the most likely—orbit for an electron is not too close and not too far from a nucleus.

Similarly, "although a mini black hole attracts atoms using gravity . the effect that prevents the mini black hole from absorbing its bound atoms is quantum mechanical."

Very rarely, an atom or molecule will get close enough to a mini black hole to be devoured. But the VanDevenders calculate that it would take much longer than the age of the universe for a mini black hole to swallow all the atoms in the Earth.

Atoms Unstable Around Tiny Black Holes?

Massimo Ricotti, an astronomer at the University of Maryland, agrees that it would be very improbable for a mini black hole to gravitationally capture an atom.

"It's very hard to accrete on tiny black holes, because they're so small," said Ricotti, who was not involved in the study. "Even if they're moving through a solid body, most of the time they find themselves almost in a vacuum, given their small size."

Ricotti is skeptical, however, about whether atoms that do get captured can form stable orbits around a mini black hole, creating a GEA.

One reason is that the orbiting atoms would likely be superheated due to the intense gravity and would develop electrical charges. The charged particles would emit electromagnetic radiation, draining energy from the particles and ultimately causing them to spiral into the black hole.

"Certainly GEAs would be interesting objects if they exist," Ricotti added.

But "I would like to better understand some issues related to the stability of the GEA and the mechanisms by which [an atom] gets accreted in the first place."


‘Seeing the unseeable’

Event Horizon Telescope researchers reveal first-ever image of a black hole

“And the reason they’re terrifying, the reason this is an important image, is because when you look into the middle of it, you realize that we’ve theorized about these monsters being out there, and now we know they are — and what’s more, now we see them,” he continued. “This is the only place in the universe where the cosmos ties a knot you can’t untie. Every other place in the universe you can, in theory, come back from, but not there.”

“Astronomers have detected many black holes since the 1970s, but in each case, only indirectly,” added Charles Alcock, the Donald H. Menzel Professor of Astrophysics and director of the CfA. “This is the first time we have an image of a black hole itself. This is a remarkable confirmation of more than a century of theoretical work.”

Seeing the image for the first time, Doeleman said, “is pretty heady stuff.”

Years ago, he recalled, while working at MIT’s Haystack Observatory, he was among the first people on the planet to see the first hints of the black hole at the center of the Milky Way.

“I started seeing these very faint detections,” he said, “so I ran some analyses to tighten up the data, and suddenly these detections came out. That was a moment where there was one person — me — in the world who knew what had just happened. That was pretty amazing.”

It was also the moment, he added, that started the modern era of the EHT. “Because as soon as we knew there was something there,” he said, “then the gloves came off and we were ready to start building an Earth-sized array to image it.”

It was in May of last year that the team hit pay dirt.

“We had a conference here at the Black Hole Initiative, and the students and postdocs came and showed me some of the data,” Doeleman said, referring to Harvard’s interdisciplinary center that studies the phenomenon. “We could see the telltale signatures in these data … and we were all just looking at it, saying, ‘Wow.’ I worked until late that night coming up with a model of how big what we were seeing was, and that’s when I knew we had something very, very interesting.”

For Joseph Pellegrino University Professor Peter Galison, the image is similar to the discovery that atoms — the fundamental building blocks of all matter — were not simply theoretical curiosities.

“At the beginning of the 20th century, in a myriad of ways, theorists needed atoms,” Galison said. “When C.T.R. Wilson showed the trails atoms made as they plunged through water vapor, suddenly it was vividly clear that these were real, not just useful fictions.”

Today, he continued, “the scientific object that rivets so many of us — from mathematics and physics to astronomy and philosophy — is the black hole. Again, theory had to have it. Now, for the first time, the black hole is visible, real to us in a way that, when I saw it first take form on the computer screen 10 months ago, knocked me back on my heels. It still does. There it is, right there, the most extreme distortion of space and time imaginable, with a mass six billion times that of the sun, 53 million light years away. And we can see it.”

In the end, Doeleman said, the discovery will be important not just for its status as a scientific first, but also for its place as a signpost, an inflection point where new avenues for study of the cosmos were revealed.

“This opens a new window for study,” he said. “We are now entering the era of precision, horizon-scale observations of black holes. We’ve never had that before, so we’re now able to ask a bunch of questions we couldn’t even conceive of before. We can start teasing apart physical processes at the black hole boundary, so [the significance] is in what we saw, but also in the promise this holds for the future.”


Astronomical observations

In Babylon and ancient Greece, astronomy consisted largely of astrometry, measuring the positions of stars and planets in the sky. Later, the work of astronomers Kepler and Newton led to the development of celestial mechanics, and astronomy focused on mathematically predicting the motions of gravitationally interacting celestial bodies. This was applied to solar system objects in particular. Today, the motions and positions of objects are more easily determined, and modern astronomy concentrates on observing and understanding the physical nature of celestial objects.

Methods of data collection

In astronomy, information is mainly received from the detection and analysis of light and other forms of electromagnetic radiation. Other cosmic rays are also observed, and several experiments are designed to detect gravitational waves in the near future. Neutrino detectors have been used to observe solar neutrinos, and neutrino emissions from supernovae have also been detected.

A traditional division of astronomy is given by the region of the electromagnetic spectrum observed. At the low frequency end of the spectrum, radio astronomy detects radiation of millimeter to dekameter wavelength. The radio telescope receivers are similar to those used in radio broadcast transmission but much more sensitive. Microwaves form the millimeter end of the radio spectrum and are important for studies of the cosmic microwave background radiation.

Infrared astronomy and far infrared astronomy deal with the detection and analysis of infrared radiation (wavelengths longer than red light). The most common tool is the telescope but using a detector which is sensitive to the infrared. Infrared radiation is heavily absorbed by atmospheric water vapor, so infrared observatories have to be located in high, dry places or in outer space. Space telescopes in particular avoid atmospheric thermal emission, atmospheric opacity, and the negative effects of astronomical seeing at infrared and other wavelengths. Infrared is particularly useful for observation of galactic regions cloaked by dust.

Historically, most astronomical data has been collected through optical astronomy. This is the portion of the spectrum that uses optical components (mirrors, lenses, CCD detectors and photographic films) to observe light from near infrared to near ultraviolet wavelengths. Visible light astronomy (using wavelengths that can be detected with the eyes, about 400 - 700 nm) falls in the middle of this range. The most common tool is the telescope, with electronic imagers and spectrographs.

More energetic sources are observed and studied in high-energy astronomy, which includes X-ray astronomy, gamma ray astronomy, and extreme UV (ultraviolet) astronomy, as well as studies of neutrinos and cosmic rays.

Optical and radio astronomy can be performed with ground-based observatories, because the Earth's atmosphere is transparent at the wavelengths being detected. The atmosphere is opaque at the wavelengths of X-ray astronomy, gamma-ray astronomy, UV astronomy and (except for a few wavelength "windows") far infrared astronomy, so observations must be carried out mostly from balloons or space observatories. Powerful gamma rays can, however be detected by the large air showers they produce, and the study of cosmic rays can also be regarded as a branch of astronomy.

Planetary astronomy has benefited from direct observation in the form of spacecraft and sample return missions. These include fly-by missions with remote sensors, landing vehicles that can perform experiments on the surface materials, impactors that allow remote sensing of buried materials, and sample return missions that allow direct laboratory examination.

Astrometry and celestial mechanics

One of the oldest fields in astronomy, and in all of science, is the measurement of the positions of celestial objects in the sky.

Careful measurement of the positions of the planets has led to a solid understanding of gravitational perturbations and an ability to predict the past and future positions of the planets with great accuracy, a field known as celestial mechanics. More recently the tracking of near-Earth objects will allow for predictions of close encounters, and potential collisions, with the Earth.

The measurement of stellar parallax of nearby stars provides a fundamental baseline in the cosmic distance ladder that is used to measure the scale of the universe. Parallax measurements of nearby stars provides an absolute baseline for the properties of more distant stars, since their properties can be compared. Measurements of radial velocity and proper motion show the kinematics of these systems through the Milky Way galaxy. Astrometric results are also used to measure the distribution of dark matter in the galaxy.

During the 1990s, the astrometric technique of measuring the stellar wobble led to the discovery of large extrasolar planets orbiting nearby stars. ⎯]

Interdisciplinary studies

Astronomy has developed significant interdisciplinary links with other major scientific fields. These include:

    : the study of the physics of the universe, including the physical properties (luminosity, density, temperature, chemical composition) of astronomical objects. : the study of the advent and evolution of biological systems in the universe. : the study of ancient or traditional astronomies in their cultural context, utilising archaeological and anthropological evidence. : the study of the chemicals found in outer space, usually in molecular gas clouds, and their formation, interaction and destruction. As such, it represents an overlap of the disciplines of astronomy and chemistry.

Galaxies and clusters

The study of objects outside our galaxy is a branch of astronomy concerned with the formation and evolution of Galaxies, their morphology and classification, the examination of active galaxies and the groups and clusters of galaxies. The later is important for the understanding of the large-scale structure of the cosmos.

Most galaxies are organized into distinct shapes that allow for classification schemes. A spiral galaxy is organized into a flat, rotating disk, usually with a prominent bulge or bar at the center, and trailing bright arms that spiral outward. These arems are dusty regions of star formation, giving them a blue tint due to the presence of young, hot stars. These galaxies are typically surrounded by a halo of older, population II stars. The Andromeda Galaxy is an example of a spiral galaxy that is part of the Local Group of galaxies.

Another prominent type is the elliptical galaxy. As the name suggests, these are shaped in an ellipse. The motions of the stars within these galaxies is random, and there is little or no interstellar dust, few star-forming regions and generally older stars. Elliptical galaxies tend to lie near the cores of galactic clusters and are believed to have formed through mergers of large galaxies.

Irregular galaxies are neither spiral nor elliptical in form, and are generally chaotic in appearance. These form about a quarter of all galaxies, and are believed to have been deformed through some type of gravitational interaction.

An active galaxy is a formation that is emitting a significant amount of its energy from a source other than stars, dust and gas. Most such galaxies are powered by a compact region at the core, usually thought to be a supermassive black hole.

A radio galaxy is an active galaxy that is very luminous in the radio portion of the spectrum, and is emitting immense plumes or lobes of gas.

Active galaxies that emit high-energy radiation include Seyfert galaxies, Quasars, and Blazars. Most active galaxies are ellipticals and are believed to be powered by a supermassive black hole that are emitting radiation due to infalling material. Quasars are believed to be the most consistently luminous objects in the known universe.

The large-scale structure of the cosmos appears to be represented by groups and clusters of galaxies. This structure is organized in a hierarchy of groupings, with the largest known being the superclusters. The collective matter is formed into filaments and walls, leaving large voids in between.


A quick recap on the team's theory: Two black holes merge in the accretion disk of J1249+3449. The event causes a flare, detected by ZTF. The event also creates a gravitational wave, detected by LIGO and Virgo. Researchers believe they've "seen" the explosion of light from a black hole merger. Now the newly formed, merged black hole has settled down, the flare has disappeared and balance appears to have been restored.

But what else can we learn?

The flare can also tell astronomers about the physical characteristics of the two colliding black holes. Ford says if the predictions are correct, then this will be "the most massive merger" observed by LIGO and Virgo yet. The merged black holes are thought to be at least 100 solar masses or more -- that is, they became at least 100 times more massive than our sun.

To get to that size, black holes would need to merge with each other over time, gradually swallowing each other up and getting more and more massive, like some sort of cosmic Katamari. And an accretion disk could be the perfect place for this, because it is within that they have the chance to court, dance with and eventually merge with each other. If this is happening in accretion disks regularly, we should be able to spot these flares more often.

Graham admits the team's predictions may, ultimately, pan out to be wrong. He even expects other scientists may have alternate explanations for the flare. But, the team's predictions are testable and when the merged black holes interact with the disk again in early 2022, the team will be watching.

"We expect to see a flaring event in a year and a half, if our model is right," he said. "That's good science."

In addition, researchers at LIGO-Virgo are studying the gravitational wave event, S190521g, intently. The gravitational wave detection should enable astronomers to work backwards and estimate the masses of the black holes that merged.

"Assuming that the LIGO observation is a genuine astrophysical signal, then LIGO's measurement of the black hole mass can be compared to the EM measurement once it's made public," said Rory Smith, the astronomer from Monash.

If they line up with what Graham, Ford and their colleagues are predicting, this could be a bonafide black hole bonanza and open up a new way to study these extreme cosmic events.

"This kind of work complements discoveries like GW190814," said Smith. "Joint gravitational-wave and EM observations bring the universe into much sharper focus."

It's been a good week for gravitational wave astronomy. On Tuesday, researchers from the LIGO and Virgo collaboration, including Smith, announced an event dubbed GW190814. The collision, between a black hole and a 'mysterious object' that might be the lightest black hole ever detected or the heaviest neutron star, poses new questions for gravitational wave astronomers about some of the most extreme phenomena in the universe.


Watch the video: Πλανήτες, Μετεωρίτες, Μαύρες Τρύπες και το ταξίδι τους. (January 2022).