4.55 Billion years is deduced from meteorites, the moon, older than the oldest earth rocks. Larger stars capable of producing higher atomic numbers. Our solar system formed as the collapse of interstellar cloud material to form proto sun and solar nebula. Another 100 million years required to sweep most of the material into the planets. Early solar system material is found in the Chondritic meteorites.
Chondrules are particles formed by no earthly process.
Chondritic composition is a model for the bulk earth. Chondrite composition matches well with sun composition. The Earth's moon is probably the result of a giant impact, based on the lack of a core, composition like Earth's mantle with little iron and volatiles. Meteorites and comets still impacting today, though thankfully infrequently. Meteorites easy to find on snow -hence large number of Antarctic discoveries.