Which form of energy transfer moves through space as electromagnetic waves from the Sun to Earth?

• A. Conduction
• B. Convection
• C. Absorption
• D. Radiation

Answer: (D)

Radiation is the transfer of energy through space via electromagnetic waves. Unlike conduction or convection, which need a solid or fluid medium to move energy, radiation can travel through the vacuum of space. The Sun emits energy as electromagnetic waves—visible light, infrared, and other wavelengths—that voyage through space and reach Earth. When these waves arrive, they can be reflected, transmitted, or absorbed, warming the planet. Absorption refers to energy taken into matter, not the mode of travel through space. Conduction and convection involve energy movement through direct contact or fluid motion within materials. So the energy transfer from the Sun to Earth through space is radiation.