He raised his hand.

I'm spending the happiest days imaginable.

I am spending the happiest days of all.

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

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.

Antarctica is the coldest place on Earth.

In geology, the continental slope refers to the point where the seabed becomes steeply deep.

The Australian continent is the smallest continent on Earth.