An astronomer I think :-o
A Planetary scientist
a parasitologist or refratorologist
Galaxy, Star System?
That is called a constellation.
a person that studies gems is called a gemologist.
A person who studies genealogies is a genealogist.
a person who studies people but not an psychologist
what do you call somebody who studies snails.
A person that studies animals is called a Zoologist.
A person who studies birds is called an ornithologist.
A person who studies birds is called an Ornitholoigst
A sociologist is a person who studies sociology.
A person who studies medicine is called a medical student.
The study is paleontology so I think a person who studies it is a paleontologist.
gerontology is the study of aging gerontologist is the person who studies it
A Mycologist studies fungi.