Meanings of planetary astronomer in English

Mike Brown planetary astronomer who is responsible for scientifically demoting Pluto to a dwarf planet

Then he grew up to become a planetary astronomer at Caltech and really did find something.

Planetary astronomers had found no evidence of oxygen in the martian atmosphere, Tombaugh reported.

Many planetary astronomers, Tombaugh added, believed that nitrogen made up the remaining nine-tenths of the martian atmosphere, though none had yet been detected.