Gravity is considered part of Physics, so Physicists do..
The possessive form of the noun gravity is gravity's.Example: Gravity's reliability is the basis of my invention.
The moon's gravity is about 1/6th of Earth's gravity.
The gravity on the moon is about 1/6th of the gravity on Earth.
Martian gravity is only 38% of the Earth's gravity.
The gravity on the moon is about 1/6th of the gravity on Earth.
A selenographer studys maps of the moon.
Botanists are people who study plants and nature.
Geology.
a cryologist
a botanist
a person who studys biographics
Geology.
Astronomer
Oceanographers o
A seismologist is aperson who Studys Earthquakes!
he studys geography
Meteorologist.