Question

which statement provides the best explanation for how the suns energy reaches earth?
the suns heat is carried by air particles to earth.
radiation transfers heat through the vacuum of space.
the earths gravity pulls heat from the sun.
heat from the sun is reflected off the moon.

Explanation:

Heat transfer from the Sun to Earth occurs through radiation. Radiation is the transfer of energy in the form of electromagnetic waves. Since space is a vacuum (no air particles), conduction (which requires direct contact of particles) and convection (which requires a fluid medium like air or water) are not possible. So, radiation is the only way for the Sun's heat to reach Earth. The first option about air particles is wrong as space is a vacuum. The third option about gravity pulling heat is incorrect as gravity is a force of attraction and not related to heat transfer in this context. The fourth option about the moon reflecting heat is not relevant to how the Sun's energy reaches Earth (it's about the Sun - Earth heat transfer, not involving the moon in the transfer mechanism from Sun to Earth).

Answer:

"Radiation transfers heat through the vacuum of space."