What is an object that revolves around another object in space called?

An object that revolves around another object in space is termed a satellite. This term broadly includes both natural satellites, like moons, and artificial ones, such as human-made spacecraft.

In this context, the essential characteristic of a satellite is its orbit around a larger body due to gravitational attraction. For example, the Moon is a natural satellite of Earth, while GPS satellites are artificial satellites that orbit Earth. This distinction as a satellite highlights the object's role in the gravitational system surrounding the planet or star it orbits.

The other options, while related, do not encompass the full definition. Moons can be considered a type of satellite, but the term “satellite” applies to a broader category of orbiting objects. Planets are larger celestial bodies that also orbit stars but are not objects that revolve around other bodies in the same sense that satellites do. Asteroids, while they might orbit the Sun or a planet, are not defined by their revolving characteristics in the same way that satellites are. Hence, the designation of satellite is the most accurate choice for an object that revolves around another object in space.