Horologist
Someone who studies the planet Mars is called an areologist.
A person who studies the planets and stars is an astrologist.
A person who studies rainbows is called a "rainbowologist."
A person who studies snowflakes is called a cryologist or a snowflake scientist.
A person who studies optometry is called an optometry student or an optometry student.
What is the name of a person that studies organisms
A person who studies sand is known as a psammologist.
A person who studies sound is called an acoustician.
An entomologist is a person who studies insects.
What is the name of a person that studies derivation of
A person who studies audiology would be called an audiologist.
I believe that they are called chronologist because chrono means time and ology means the study of
A person who studies time.
mr. djw studies dinos
Etymologist
zoologist
A dietician.