Mars and Neptune Conjunction, inlcuding the Moon and Venus

   A previous post described the daily motion of Mars as it moves toward the planet Neptune. Well Monday evening January 2nd the planets Mars and Neptune, and our Moon (a 5-day old waxing crescent Moon) will all fit within the field of view of binoculars with Mars and Neptune separated by about 1.5o.

   In that post I had also mentioned that were Neptune observed from the surface of Mars then Neptune would be starting its retrograde motion. Actually I was not entirely correct as I was basing this on how the two planets looked from Earth rather than Neptune as seen from Mars. Compare the distance between the Earth and Mars and the difference between the orbital speed of the two planets. Then consider Mars and Neptune where there is a greater difference between the orbital speeds of Mars and Neptune as well as the distance between the Mars and Neptune then there is between the Earth and Mars.

   What this means is that Neptune, as viewed from Mars, will not actually begin to retrograde until around the middle of June.


Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

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