- Rainbows are formed when light goes through water droplets and bends at different angles.
- The sun’s atmosphere has elements that absorb specific wavelengths.
- If you look at a star and see a gap in the wavelengths, you know what elements it has.
- Redshift is when something going away from you shifts towards the red end of the spectrum. Blueshift is when something coming towards you shifts towards blue.
- ”Standard candles” allow us to measure changes in brightness of distant stars, and figure out how far away they are.
The Big Bang
- Hubble discovered that things further away are moving faster away from us.
- From this, he concluded: The Universe is expanding unformly.
- When things expand uniformly, further things move away at higher rates.
- If you reverse this process, everything goes back to one point that contains everything. At the very beginning, it was just energy (the Big Bang).
First 3 minutes of the Big Bang
Protons and neutrons smashed together, forming hydrogen and helium.
- The vast majority of all helium in existence today was made during this time.