Why is Venus the hottest planet in the solar system, even though Mercury is closer to the Sun?

• A. Venus is closer to the Sun than Mercury.
• B. Venus rotates faster than Mercury, causing more friction and heat.
• C. Venus absorbs more solar energy because its surface is darker than Mercury's.
• D. Venus has a thick atmosphere rich in CO_2 that traps heat through the greenhouse effect.

Answer: (D)

Verified step by step guidance

1. Understand that the temperature of a planet depends not only on its distance from the Sun but also on its atmospheric properties.
2. Recall that Mercury, although closer to the Sun, has a very thin atmosphere, which means it cannot retain much heat and experiences extreme temperature fluctuations.
3. Recognize that Venus has a very thick atmosphere composed mainly of carbon dioxide (CO_2), a greenhouse gas that traps heat effectively.
4. Learn about the greenhouse effect: solar radiation passes through the atmosphere and warms the planet's surface, but the thick CO_2 atmosphere traps the infrared radiation emitted by the surface, preventing heat from escaping into space.
5. Conclude that this trapped heat causes Venus to have a much higher average surface temperature than Mercury, making it the hottest planet in the solar system despite being farther from the Sun.