MISSION EXPLORING THE COSMOS Have you ever looked up at the night sky You might see 2 000 stars You could also see the moon planets and satellites All of these belong to the universe or cosmos But they only make up a tiny portion of it Mysterious Universe The universe is enormous It holds billions of galaxies and trillions of stars It is also home to mysterious phenomena scientists are still trying to comprehend Scientists are just beginning to understand black holes dark matter and other celestial mysteries Understanding the Cosmos The universe's massive size makes it hard to study But scientists are trying to unlock its secrets They hope
The Milky Way is our home galaxy On a clear night with little light pollution it can be seen from Earth to understand how the universe formed Scientists are also looking at how it grew and changed They hope this will provide clues on how and if the universe could end someday far in the future
CHAPTER 1 THE MASSIVE UNIVERSE The universe is a mysterious place It contains everything that exists This includes space matter energy and time No one knows exactly when the universe began But many scientists believe it is about 14 billion years old No one knows how big the universe is either However scientists have found evidence that the universe is constantly expanding Scientists also don't know the shape of the universe for certain Most believe it is flat However some scientists believe the universe curves outward like a balloon And others believe it curves inward like a saddle DID YOU KNOW The only known universe is the one we live in But some scientists believe that there are many different universes seat
Astronomers believe there are 10 billion galaxies in the observable universe They could hold trillions of stars The part of the universe we can study is spherical This sphere is known as the observable universe It contains all the light that has had time to reach us We cannot see beyond this region Scientists believe it may be 93 billion light years wide Earth sits in the center of the observable universe
