Which energy transfer method is responsible for heat moving from the Sun to Earth through empty space?

Which energy transfer method is responsible for heat moving from the Sun to Earth through empty space?

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

Answer: (B)

Heat moving through empty space from the Sun to Earth is carried by radiation. Radiation transfers energy as electromagnetic waves, which don’t need a medium to travel, so these waves can move through the vacuum of space and warm the Earth when they are absorbed by the atmosphere and surface. Conduction requires direct contact between materials, and convection relies on moving fluids to transfer heat; in space there’s essentially no matter to carry heat, so those methods can’t operate there. Advection is a way heat can be transported by bulk fluid flow, which isn’t applicable in the near-vacuum of space. So radiation is the mechanism that delivers solar energy across space.

Heat moving through empty space from the Sun to Earth is carried by radiation. Radiation transfers energy as electromagnetic waves, which don’t need a medium to travel, so these waves can move through the vacuum of space and warm the Earth when they are absorbed by the atmosphere and surface. Conduction requires direct contact between materials, and convection relies on moving fluids to transfer heat; in space there’s essentially no matter to carry heat, so those methods can’t operate there. Advection is a way heat can be transported by bulk fluid flow, which isn’t applicable in the near-vacuum of space. So radiation is the mechanism that delivers solar energy across space.