The Universe

The Universe is everything that exists now, everything that existed in the past and everything that will exist in the future. In other words, the Universe consists of all of space and all of time ("spacetime") and anything that exists within spacetime.

The observable Universe is centered on Earth because that's where we're observing from. On this scale, the Milky Way galaxy is far too small to be visible. The smallest things you can see in this image are groups of superclusters of galaxies.

Credit: Andrew Z. Colvin

There are more stars in the Universe than grains of sand on the Earth.
The prevailing theory about the history of the Universe is the Big Bang theory. This proposes that the Universe was in a much smaller, denser, hotter state 13.8 billion years ago, and has been expanding and cooling ever since.
The early Universe would have consisted mostly of hydrogen and helium gases. These gases began falling into clumps and eventually made stars and planets. It appears that the first stars and galaxies were born within a few hundred million years of the Big Bang.
Old television sets made a random static pattern when they weren't tuned to a channel. About 1% of this static is caused by radiation left over from the Big Bang.
Currently, the observable Universe is estimated to be around 93 billion light-years in diameter.
Until the 1920s, most astronomers thought the Milky Way galaxy contained everything in the entire Universe. We now know that it's just a tiny part of the Universe.
As far as we know, there's only one Universe. Astronomers don't rule out the possibility of more universes (a multiverse) but so far we have no evidence to support this.
Gravity slows down time. In space, time passes more quickly than it does on Earth.
There is no such thing as zero gravity. Technically speaking there is at least some tiny amount of gravity everywhere throughout the entire Universe.
The first planets found outside our own Solar System were discovered in the 1980s. Since then astronomers have found thousands of planets in other solar systems. We assume there are planets throughout galaxies across the Universe.