Why galileo thinks the earth is not the center

You have to remember that Galileo Galilei was a scientist. He studied space and used a telescope and with it he figured out that the earth evolved around the sun not the sun around the earth.

radioactive dating, also known as  radioisotope dating  is a process that in  estimating the approximate  age  of  rocks. these data can be analyzed from  the studies dealing with the  decay of the radioactive elements that are present in these rocks. in nature, there are a few types of materials or atoms which are quite unstable and they spontaneously decay or breakdown to form other kinds of atoms.