Earth Science

Beyond the Solar System

Big Bang

Study Tip
After discovering that the universe was expanding, scientists concluded that the universe must have started out as a smaller point.

How It Happened

  • The Big Bang theory is used to explain the creation of the universe and all the planets, galaxies, and stars within it.  
  • Around 15 billion years ago all matter and energy was concentrated into a very small area called a singularity.
  • The dense and extremely hot singularity began expanding at a very fast rate expelling high-energy matter in all directions.
  • Electrons, protons, and neutrons began to form immediately after the explosion.
Study Tip
After discovering that the universe was expanding, scientists concluded that the universe must have started out as a smaller point.

Evidence for the Big Bang

  • If the universe were static, then the space between objects should not have any heat. In 1964, however, scientists discovered that there was in fact a temperature associated with the space between objects.
  • Light from distant galaxies, captured in a prism from a telescope, displays a trend where light tends to approach the red spectrum. The Doppler effect explains how the shifting towards red indicates that the universe is expanding.
Big Bang
This is a timeline of the universe’s history. Microwave light captured by the Wilkinson Anisotropy Microwave Probe also gives proof that the universe started with a blast.
Concept Check
  • What is the Big Bang theory?
  • How do scientists use evidence to support this theory?