Here's why:

* Focus on celestial objects: Astronomers study celestial objects like stars, planets, galaxies, nebulae, black holes, and more. These objects are all located beyond Earth.

* Understanding the cosmos: Their research aims to understand the origin, evolution, composition, and properties of the universe.

* Using telescopes and other instruments: Astronomers use a variety of tools, primarily telescopes (both ground-based and space-based), to observe and collect data about distant celestial objects.

So, if someone is studying the universe beyond Earth, they are most likely an astronomer.