Emerald Robinson: Hi! My name is Emerald Robinson, and this "what is" video is going to tackle a big question - What is the Universe?
The universe is, in a word: everything. All matter from atoms and subatomic particles to the stars, the planets, and galaxies. All things that existed and will ever exist in the future, these things make up the universe.
Most scientists think that the universe originated at least 13.
7 billion years ago. All of the matter that existed was concentrated in a very hot and dense mass. No matter exploded away from this point and continues to expand, cooling as it moves away from this central location. This model is known as the "Big Bang" and is the most commonly accepted theory about how the universe started.
We don't know how big the universe is. But it's so big that we use a unit called a "light year" to measure distances between objects. A light year is the distance that light travels in a year, about 6 trillion miles. We've been able to determine that the universe is about 28 billion light years across, and we suspect it's bigger than that.
Where does the earth fit in? Our solar system is part of a system of billions of stars called a galaxy. Our galaxy is called the Milky Way. The Milky Way is one of a group of galaxies called the "Local Group". And this group is, in turn, part of a cluster of galaxies. Millions of these clusters are strung together throughout the universe.
Although, the scope of the universe is unfathomable, we still try to make sense of it. Ancient civilizations observed the movements of objects in the sky using simple tools.
Today, scientists called cosmologists use high powered telescopes and equipment such as spectroscopes to study the origin and evolution of the universe.