It could be an astronomer, although more likely an astrophysicist or cosmologist.
You call someone that studies metal a metallurgist.
A physicist.
a person who studies planets is a planetologist.
An astronomer.
Someone who studies astronautics is typically referred to as an astronautical engineer or a space scientist. Astronautical engineers focus on the design and development of spacecraft and related technologies, while space scientists may study celestial phenomena and the physical principles governing space exploration. Both fields contribute to our understanding and advancement of space travel and exploration.
There is no special name for someone who studies Hebrew.
florist
Microbiologists
An Anthropologist.
malacologist
A Zoologist
Brocollogist