How old is the sun.

4,5 billion to 5 billion years

Explanation:

Sun is estimated to be around 4,5 billion years old.

This is determined by dating the material find in meteorites coming from the space. The solar system has formed at the same time, from the same molecular cloud. That is why the material from the lunar samples was used to see how old is the Sun. The method used is called Rubidium-strontium dating method because it the isotopes of elements of rubidium (Rb) and strontium (Sr) are analyzed and dated.