Heat from the sun moves through space by the process of

Radiation

Explanation:

There are three modes of heat transfer:

Conduction: Heat transfers from hotter body to colder one via conduction when they are placed in contact with each other. The molecules vibrate and transfer heat.

Convection: Heat transfers in fluids via convection. The heat is carried by bulk motion of fluid.

Radiation: Heat transfer through space takes place via radiation. The electromagnetic waves carry the energy from the Sun and moves through space. This mode does not depend on the medium. The electromagnetic waves carry the energy and travel at the speed of light.