*The rate at which radioactive decay occurs.
*How much radioactive decay has occurred.
Yes, They all are! They all can be the start of something.
Stars Like the Sun. When the core runs out of hydrogen fuel, it will contract under the weight of gravity. ... The upper layers will expand and eject material that will collect around the dying star to form a planetary nebula. Finally, the core will cool into a white dwarf and then eventually into a black dwarf.
