© NASA/Cassini

Jupiter ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed

Objects: Jupiter
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The sky at

Jupiter will reach the end of its retrograde motion, ending its westward movement through the constellations and returning to more usual eastward motion instead. This reversal of direction is a phenomenon that all the solar system's outer planets periodically undergo, a few months after they pass opposition.

The retrograde motion is caused by the Earth's own motion around the Sun. As the Earth circles the Sun, our perspective changes, and this causes the apparent positions of objects to move from side-to-side in the sky with a one-year period. This nodding motion is super-imposed on the planet's long-term eastward motion through the constellations.

The diagram below illustrates this. The grey dashed arrow shows the Earth's sight-line to the planet, and the diagram on the right shows the planet's apparently movement across the sky as seen from the Earth:

The retrograde motion of a planet in the outer solar system. Not drawn to scale.

2016 apparition of Jupiter

07 Jan 2016 – Jupiter enters retrograde motion
08 Mar 2016 – Jupiter at opposition
08 Mar 2016 – Jupiter at perigee
09 May 2016 – Jupiter ends retrograde motion

Observing Jupiter

Jupiter leaves retrograde motion as its 2016 apparition comes to an end, although it will remain visible for some weeks in the dusk sky.

Its celestial coordinates as it leaves retrograde motion will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Jupiter 10h59m30s 7°55'N Leo -2.2 39.0"

The coordinates above are given in J2000.0.

From Seattle , it will be visible in the evening sky, becoming accessible around 20:54 (PDT), 50° above your southern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 20:55, 50° above your southern horizon. It will continue to be observable until around 02:42, when it sinks below 7° above your western horizon.

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Over the following weeks, Jupiter will reach its highest point in the sky four minutes earlier each night, gradually disappearing into evening twilight.

The sky on 9 May 2016

The sky on 9 May 2016
Twilight ends
Twilight begins

3-day old moon
Waxing Crescent


3 days old

Rise Culm. Set
Mercury 05:39 13:03 20:27
Venus 05:26 12:35 19:44
Moon 08:25 16:09 23:53
Mars 21:52 02:13 06:33
Jupiter 14:16 20:55 03:33
Saturn 22:26 02:52 07:18
All times shown in PDT.


The circumstances of this event were computed using the DE430 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).

This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.

Related news

08 Mar 2016  –  Jupiter at opposition
07 Apr 2017  –  Jupiter at opposition
08 May 2018  –  Jupiter at opposition
10 Jun 2019  –  Jupiter at opposition

Image credit

© NASA/Cassini





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