What is the Universe?
The universe contains everything that exists, including Earth, planets, stars, space, and galaxies. This includes all matter, energy, and even time.
How big is the Universe?
No one knows for sure how big the universe is. It can be infinitely large. However, scientists measure the size of the universe by what they can see. They call it the “observable universe”. The observable universe is about 93 billion light-years across.
The Universe is Expanding
One of the interesting things about the universe is that it is currently expanding. It’s getting bigger all the time. Not only is it growing, but the edge of the universe is expanding at an increasing rate. Scientists believe that the edge of the universe is expanding faster than the speed of light.
What is the Universe made of?
Although the Earth seems very big to us, it is actually only a very small part of the universe. The Sun has 330,000 times the mass of the Earth. The Sun is just one star in the Milky Way which contains more than 300 billion stars, and scientists estimate that there are more than 170 billion galaxies in the universe!
However, most of the universe is what we think of as empty space. All of the atoms together make up only about four percent of the universe. Most of the universe is made up of what scientists call dark matter and dark energy.
What are dark matter and dark energy?
We mentioned above that much of the universe is made up of dark matter and dark energy, but what exactly are these?
Dark matter – Scientists don’t know exactly what dark matter is, but they believe it exists through experiments. Dark matter gets its name from the fact that it cannot be seen with any kind of instrument we have today. About 27% of the universe is made up of dark matter.
Dark energy – Dark energy is what scientists think fills space. It turns out that “empty space” is nothing more, but it really is dark energy. Dark energy theory helps scientists explain why the universe is expanding. About 68% of the universe is dark energy.
How old is the Universe?
Scientists believe that the universe began 13-14 billion years ago with the beginning of a massive explosion called the Big Bang.
Interesting Facts about the Universe
Distant galaxies are constantly moving away from us as the universe expands.
Each galaxy in the universe is moving away from all the others. There is no center in the universe.
Albert Einstein said that the shape of the universe is open, closed or flat. Many scientists today believe that the universe is flat.
The universe appears to be cooling and possibly freezing. The large void in the universe is called the void.
The most abundant element in the universe is hydrogen. The second most abundant element is helium.