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Apparent Magnitude of planets as seen from earth

  1. Jan 24, 2008 #1
    I've seen that Mars' apparent magnitude varies between -2.9 and 1.8 and Mercury's from -2.0 and 5.5 (wikipedia said so at least).
    I'm trying to figure out which planet would have the greatest variation in brightness, as seen from Earth. The numbers at wikipedia points in the direction of Mercury, but I can't explain why it should be either planet.

    Would it be Mercury? Because when in inferior/superior conjunction it's not visible due to the much brighter sun?
    Would it be Mars? Because of the retrograde motion when it's in opposition?

    Any help would be appreciated :)
  2. jcsd
  3. Jan 24, 2008 #2
    I'd say Venus, because it's the brightest among all planets as viewed from Earth(around -4.5 at the peak). And during inferior conjunction, and especially when it's in a solar transit, it's basically a black disk. Unlike planets beyond Earth, Mercury and Venus have phases like the Moon.
  4. Jan 27, 2008 #3
    The motion of all planets are defined clearly, so it is imposible to mix among them.
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