[SciShow intro plays]   Reid: Earth does a pretty good job of keeping us carbon-based life forms alive. For one thing, it’s the only planet we know of that has stable liquid water on its surface. We have found evidence of water vapor and water ice all over, though -- like on asteroids, comets, Mars, and Pluto. But astronomers were surprised to discover the largest reservoir of water in the known universe more than 12 billion light years away.   It contains around 140 trillion times the amount of water in Earth’s oceans -- in the form of water vapor -- and it’s floating around a black hole with a mass of about 20 billion Suns, inside an object called a quasar. Quasars are some of the oldest and brightest objects in the universe. They were first discovered in the late 1950s, when astronomers were scanning the sky and picked up radio emissions that weren’t coming from any objects that they could see.   In the 1960s, astronomers were able to use both radio telescopes and optical telescopes to take a better look. What they found kinda looked like dim stars, but didn’t emit the wavelengths of light that stars normally would. So they called the objects quasi-stellar radio sources.   But that was a mouthful, so they shortened it to quasars, or QSOs. Later, astronomers discovered other types of quasars that were radio-quiet -- ones that emit much, much weaker radio waves -- and continued to learn more about these mysterious objects. Quasars are now defined as part of a class of objects called Active Galactic Nuclei.   They’re in the center of some of the oldest galaxies in the universe, and are regions of space surrounding supermassive black holes. Dust, gas molecules, and other particles swirl around the black hole, moving at really high speeds and smashing into each other. This causes the quasar to give off lots of energy in many different forms, like radio waves, X-rays, gamma rays, or light.   But even though quasars are some of the brightest objects in the universe, they’re still really hard for us to see, because they’re so far away. And that brings us to our huge water reservoir quasar, which hangs out 12 billion light years away in the direction of the constellation Lynx, which is the squiggly line of stars between Gemini and the Big Dipper. The quasar itself was first discovered in the ‘90s, but all of the water inside wasn’t found until the late 2000s -- by two separate teams at the California Institute of Technology.   The researchers expected to find water vapor in the distant, early universe, but they’ve never found so much so far away. The water vapor’s also a lot warmer than they thought it would be. X-rays and infrared radiation emitted from the quasar is heating the water vapor to about minus 53 degrees Celsius.   This might sound pretty chilly, but it’s still around five times warmer than the water vapor floating around in most galaxies, like the Milky Way. And since it took the light from the quasar 12 billion years to get here, scientists are looking at the quasar when the universe was much, much younger. So studying objects like this can tell astronomers a little more about the evolution of the universe after the Big Bang.   For example, you can’t have water without hydrogen atoms and oxygen atoms -- H2O, right? But the early universe didn’t have oxygen until early stars formed. So a whole bunch of stars had to live and die before there were even enough elements to make the ancient water that astronomers are seeing now. And scientists think that all this water vapor could eventually condense into new stars, or be sucked into the supermassive black hole, which would make the black hole grow even larger -- up to 6 times its current size.   Better technology will help astronomers find more distant, ancient water reservoirs like this quasar -- or other important and weird things in the early universe. And learning more about them just might help us understand how water, and life, and... all this... got here.   Thanks for watching this episode of SciShow Space, and thanks especially to our patrons on Patreon who help make this show possible. If you want to help us keep making episodes like this, just go to Patreon.com/SciShow to learn more. And don’t forget to go to YouTube.com/SciShowSpace and subscribe!