Mercury Is Always Much Closer to the Sun Than Venus

question 41

Multiple Choice

Mercury is always much closer to the Sun than Venus is, and yet it never appears brighter than Venus, even at maximum brightness. Explain.

• A) We never see more than a small fraction of Mercury's illuminated surface because of its orbital path relative to that of Earth; hence it always appears dark.
• B) Mercury has a thick atmosphere that impedes reflection from its surface and hence appears dark.
• C) Mercury has a high albedo, or reflectivity, but it is very small and hence appears relatively dark.
• D) Mercury is small, has a dark surface, and has no reflecting clouds.