© NASA/Cassini

Jupiter ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed

Objects: Jupiter
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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.

2019 apparition of Jupiter

10 Apr 2019 – Jupiter enters retrograde motion
10 Jun 2019 – Jupiter at opposition
11 Aug 2019 – Jupiter ends retrograde motion

Observing Jupiter

Jupiter leaves retrograde motion as its 2019 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 16h51m40s 22°06'S Ophiuchus -2.4 40.5"

The coordinates above are given in J2000.0.

From Ashburn , it will be visible in the evening sky, becoming accessible around 20:31 (EDT) as the dusk sky fades, 28° above your southern horizon. It will then reach its highest point in the sky at 20:43, 28° above your southern horizon. It will continue to be observable until around 00:37, when it sinks below 7° above your south-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 11 August 2019
Sunrise
06:19
Sunset
20:11
Twilight ends
21:55
Twilight begins
04:39

10-day old moon
Waxing Gibbous

89%

10 days old

Planets
Rise Culm. Set
Mercury 04:50 11:59 19:09
Venus 06:16 13:16 20:15
Moon 17:45 22:39 03:28
Mars 06:55 13:45 20:35
Jupiter 15:57 20:43 01:29
Saturn 18:10 22:55 03:40
All times shown in EDT.

Source

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

10 Jun 2019  –  Jupiter at opposition
14 Jul 2020  –  Jupiter at opposition
19 Aug 2021  –  Jupiter at opposition
26 Sep 2022  –  Jupiter at opposition

Image credit

© NASA/Cassini

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39.04°N
77.49°W
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