His usual location is the seat at the very back of the library.

I am an Earthling.

We are searching for extraterrestrial life.

The process of terraforming is part of transforming other planets into a habitable environment for humans.

Earth science is an important field of study for unraveling the mysteries of nature.

Global warming is a big issue that affects all of us.

He is an expert in geophysics.

He believes in the geocentric theory.

A terrestrial planet may have an environment similar to Earth.

He is brushing his upper teeth.