The Stellar Guide
By JACK LEVINE, NOAH RUSSELL, BRIE MULDOON
How Elements are Discovered in Stars
Elements in The Sun
Why this is Helpful for Astronomers
Spectroscopy tells us the age of a star by looking at the amount of its matter made up of chemical elements other than hydrogen and helium.
"The earliest stars were composed of just hydrogen and helium because they were the first elements to form after the Big Bang".
As these first stars reached the end of their lives and ran out of hydrogen fuel to fuse into helium, they began fusing helium into heavier and heavier elements, eventually producing iron.
Because stars can't fuse iron into anything heavier, gravity takes over, collapsing the star and causing a supernova explosion, seeding the universe in heavier elements from which the next generation of stars are born.
Knowing the age helps astronomers to find planets. The stars that are older mean the planets around them are older which means life could of formed.