What is the difference?

[Manok101]

Looking at the moon and mercury (via photos) the moon seems far brother what makes one more reflective looking than the other?

[rowan46]

mainly distance, I think being spherical some of the rays reflect at a different angle of incidence and shoot off into space. Think of it like this if I move 1 degree off my target which is say 100 yards away I will be perhaps 10 yards off my target. If I walked 1degree for 10 miles I would be a much further distance off my target. (The maths is pure guesswork by the way I havent worked it out. ) the analogy holds for the moon. my guess is that if they were the same distance away mercury would be brighter as it is larger. (This is pure guesswork on my part and may be something I've completely invented and hence wrong)

[1337geeza]

Good guess work, I'm not sure either but I think you may be right, and explained superbly!

[ollypenrice]

The key term is albedo, a measure of reflectivity. I copied these albedo values from Wiki Answers... Venus is a big hitter because of its clouds, those charming ones which deluge the unhappy Venutians with torrents of concentrated sulphuric acid!

Mercury - 0.106

Venus - 0.65

Earth - 0.367

Moon - 0.12

Mars - 0.25

Jupiter - 0.52

Europa 0.67

Saturn - 0.47

Enceladus 1.375

Uranus - 0.51

Neptune - 0.41

Dwarf Planets

Pluto - 0.49 -> 0.66 depending on where it is in it's orbit

Eris - 0.86

Ceres - 0.090

Olly

[Manok101]

Thanks, seems like you figured out what I meant even with the ipad correcting me wrongly.

[MorningMajor]

Not forgetting the 43,700,000 miles difference in distance!

Venus is a big hitter because of its clouds, those charming ones which deluge the unhappy Venutians with torrents of concentrated sulphuric acid!

And to think we complain about the clouds, Olly!!