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Jupiter at 15 Day Intervals

Jupiter at 15 Day Intervals (8 November – 8 May)

   A Backwards Jupiter, or when the giant planet starts retrograde motion. Tuesday December 9th the largest planet in our solar system, Jupiter, begins its retrograde motion. Retrograde motion is an apparent motion that the outer planets, relative to the Earth, have. It is an apparent motion that looks as if the outer planet stops it normal direct motion to the east and reverses direction to the west. After a period of time the apparent westward motion ends and the planet resumes its normal orbital path to the east. Retrograde motion happens as the faster moving Earth catches up with and then passes by the outer planet. It is during this time that the backward apparent motion happens.
   The two inner planets also have retrograde motion but it is a result of their orbit around the Sun and not the Earth passing them by. For approximately one-half of their orbit they move east, from western elongation through superior conjunction to eastern elongation. Then at eastern elongation the inner planet starts moving westward through inferior conjunction to western elongation.
   Read a little more about retrograde motion in my February 2012 Scope on the Skies column, drawkcab planets, in Science Scope Magazine.
Click on graphic to see it full size.

Click on graphic to see it full size.

   Where is Jupiter now? Jupiter is a few degrees west from the star Regulus in Leo the Lion. Jupiter rises around midnight local and is visible above the horizon the remainder of the night.

Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

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