Final answer:
Infrared radiation is the form of radiation from the sun that can't be seen but is felt as heat, transferring energy through space without requiring a medium.
Step-by-step explanation:
One form of radiation from the sun that you can't see but can feel is infrared radiation. This type of electromagnetic radiation is not visible to the human eye, but it can be felt as heat. Like other forms of radiation, infrared transfers energy through the vacuum of space, which means it does not require a medium to travel through. This is why you can feel the sun's warmth despite the vast emptiness of space between the Earth and the sun. Infrared radiation is one of the different types of electromagnetic waves which also include radio waves, microwaves, visible light, ultraviolet radiation, X-rays, and gamma rays. The infrared radiation absorbed by our skin is what gives us the sensation of warmth from the sun.