Earth Science

Beyond the Solar System

Universe

Study Tip
Everything that exists in the world is unified inside the universe.

The Universe

  • The universe contains all the matter and energy that has ever existed. The universe includes all of space and time.
  • The idea that more than one universe exists is called the multiverse hypothesis.
  • Cosmology is the study of the universe.
Study Tip
Everything that exists in the world is unified inside the universe.

Evolution of Human Understanding of the Universe

  • The ancient Greeks believed that the Earth was the center of the universe, and their model of the universe contained five planets, the Earth, the Sun, the Moon, and a sphere which had stars attached to it.
  • Galileo‚Äôs telescope allowed people to realize that the Earth is not the center of the universe.
  • An astronomer named Edwin Hubble discovered the Andromeda Nebula, which was 2 million light years away.
  • This object was at a much farther distance than anything else that had been previously measured. Hubble realized that objects that were thought to be nebulas, or clouds of gas, were actually collections of stars that we now call galaxies.
  • Hubble demonstrated that the universe was much larger than the size of our galaxy, and that the universe is much bigger than anyone had ever imagined.
Concept Check
  • What is a universe? What does it contain?
  • How did our understanding of the universe evolve over time?