How does heat energy from the Sun reach the Earth?

• A. By conduction
• B. By convection
• C. By reflection
• D. By radiation

Answer: (D)

Verified step by step guidance

1. Understand the three modes of heat transfer: conduction, convection, and radiation. Conduction is heat transfer through direct contact between materials, convection is heat transfer through fluid movement, and radiation is heat transfer through electromagnetic waves.
2. Recognize that space between the Sun and Earth is a vacuum, meaning there is no medium (like air or solid matter) for conduction or convection to occur.
3. Recall that radiation does not require a medium and can transfer energy through empty space via electromagnetic waves, such as visible light and infrared radiation.
4. Apply this knowledge to the problem: since the Sun's heat travels through the vacuum of space to reach Earth, the mode of heat transfer must be radiation.
5. Conclude that the correct answer is 'By radiation' because it explains how heat energy from the Sun reaches the Earth across the vacuum of space.