The Big Bang
Three pieces of evidence for the origin of the universe
Do Now: Almost every galaxy we see is moving away from us. Does that mean Earth is at the center of the universe?
No! Observers in any galaxy would see the same thing: all the other galaxies moving away. Space itself is stretching, so there is no center. Try it below with “Make the target my home.”
Try It First
Press Expand. Click any galaxy to make it the target and see its spectrum.
The Big Idea
1. Redshift
Distant galaxies are moving away from us — and the farther they are, the faster they go. The universe is expanding.
2. Cosmic Microwave Background
A faint glow of microwaves fills the whole sky — the leftover heat of the early universe.
3. Composition
Ordinary matter is about ¾ hydrogen and ¼ helium — just what the Big Bang predicts.
Lessons
NYS P-12 Science Learning Standards: HS-ESS1-2 — Construct an explanation of the Big Bang theory based on astronomical evidence of light spectra, motion of distant galaxies, and composition of matter in the universe.