Light takes a long time to reach us, showing what was happening in the universe billions of years ago.
Speed of Light and Stellar Distances
The farther apart two objects in space are, the faster they are moving away from each other.
We can observe the formation of new galaxies around supermassive black holes.
Hubble's Law
We can calculate the ages of objects in the solar system using radioactivity.
The universe is expanding.
Stellar Life Cycles
Knowing this allows us to understand the size and age of the universe.
Everything in space is moving away from everything else.
Empty space in the universe is filled with microwave radiation.
Quasars
We can determine how long it takes stars to grow and develop.
Photons are cooling and redshifting over time.
Knowing how fast light moves lets us know how long it takes to travel a certain distance.
Only observed between 10-15 billion light years away.
Cosmic Background Radiation
Using half-life calculations lets us know the relative ages of objects.
Observations tell us how stars grow and change over time.
Radioactive Decay
