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THREAD: Need a break from #BlackFriday, digging @NASA’s #BlackHoleFriday? Perfect, enjoy our Black Hole 101! 
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First the basics. A black hole is a region in space where the pulling force of gravity is so strong that light is not able to escape. Because of this, black holes are invisible. Only telescopes with special instruments can help find them.pic.twitter.com/FrtezHvpDY
There are three main types of black holes. The black hole's mass and size determine what kind it is.pic.twitter.com/Xt7wrjlHjz
The smallest ones are known as primordial black holes. Scientists believe this type of black hole is as small as a single atom but with the mass of a large mountain.pic.twitter.com/le3gu7sOFr
The most common type of medium-sized black holes is called "stellar." The mass of a stellar black hole can be up to 20 times greater than the mass of the sun and can fit inside a ball with a diameter of about 10 miles.pic.twitter.com/bD3XlBzYYn
Did you know dozens of stellar mass black holes may exist within the Milky Way galaxy?pic.twitter.com/VevW13PR7d
The largest black holes are called "supermassive." These black holes have masses greater than 1 million suns combined and would fit inside a ball with a diameter about the size of the solar system.pic.twitter.com/WL6URMpgZj
Primordial black holes are thought to have formed in the early universe, soon after the big bang.pic.twitter.com/HlTa4dqbmK
Stellar black holes form when the center of a very massive star collapses in upon itself. This collapse also causes a supernova, or an exploding star, that blasts part of the star into space.pic.twitter.com/SaZCMuKIcR
Scientists think supermassive black holes formed at the same time as the galaxy they are in. The size of the supermassive black hole is related to the size and mass of the galaxy it is in.pic.twitter.com/MfYisjnouG
If a black hole with the same mass as the sun were to replace the sun, Earth would not fall in. The black hole with the same mass as the sun would keep the same gravity as the sun.pic.twitter.com/QEpdLd1Lhg
NASA is learning about black holes using information from @NASAHubble,@chandraxray
@NASAFermi, and @NASAspitzer.pic.twitter.com/UXPetPKI6E
Want to learn more about black holes? Ask a question with #AskNASA #BlackholeFriday. More here on black holes: https://www.nasa.gov/black-holes pic.twitter.com/tSaGH2kCBj
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