What is it that radiant heat can travel through that the other forms of heat transfer cannot?

The radiant heat can travel through vacuum but other forms of heat cannot travel through it.

Explanation:

Radiant heat is heat energy in the form of radiation. Radiation does not require any material to travel.

Earth receives energy from sun in the form of radiant heat. This is possible as radiant heat moves as waves.

Other two forms of heat energy : conduction and convection, require material medium to travel. So they can't be transmitted in space or vacuum.

All hot objects radiate heat energy in the form of infrared waves that moves from hot surface to cold surface.