They will change shape from the air and rain and fog and other weather.
Radioactive dating, also known as carbon 14 dating
A glance at the night sky above Earth shows that some stars are much brighter than others. ... Astronomers define star brightness in terms of apparent magnitude — how bright the star appears from Earth — and absolute magnitude — how bright the star appears at a standard distance of 32.6 light-years, or 10 parsecs.
