At the subatomic level, space is never truly empty. It is filled with a writhing, active population of “Virtual Particles” that pop in and out of existence. Physicists call this “quantum foam”. Physicists theorize fluctuations from this field of energy may have given rise to the Universe.
The Fermi Paradox states that given how large our universe is, evidence of alien life should have been found by now, leading some scientists to believe that alien civilizations have purposely been keeping us in the dark.
There is a theory that predicts that the universe is a projected 3D illusion created by a 2D surface on the outermost edges of space. Not too different from a hologram.
In 2008 there was a gamma ray burst, a violent cosmic explosion, 7.5 billion light years away, which is halfway across the visible universe, which could have been seen with a naked eye from the surface of the Earth. Anyone who saw it was looking billions of years into the past with their eyes.
After Betelgeuse goes supernova, it will be brighter than a full moon and visible during the day. It will shine for weeks/months before fading away. It will likely explode within a million years.
In googol (10^100) years, the universe will be virtually empty.
Something astoundingly huge in a distant region of space is attracting whole galaxies towards it. Known as “The Great Attractor”, it must be monumental in size to generate such a gravitational pull; in fact, many physicists argue that it is physically impossible for such a massive object to exist at all.
Hydrogen is a light, odorless gas, which, given enough time, turns into people. First hydrogen has to turn into helium (in a star), then the helium has to turn into even heavier elements (also in a star), then the heavier elements need to turn into a planet (after the star explodes), then that planet has to produce life (through abiogenesis(we’re actually not quite sure how this specifically happened on earth), and then that life has to turn into people (through evolution).
If you could fold a piece of paper in half 103 times it would be as thick as the observable universe.
The largest known star is 4,982,686,912 times bigger than the sun, and is only 9,500 light-years away. If placed at the center of the Solar System, its photosphere would engulf the orbit of Jupiter, although the radius is not known for certain and may be larger than the orbit of Saturn.