© NASA/Cassini

Saturn ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed

Objects: Saturn
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The sky at

Saturn 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.

2013 apparition of Saturn

18 Feb 2013 – Saturn enters retrograde motion
28 Apr 2013 – Saturn at opposition
08 Jul 2013 – Saturn ends retrograde motion

Observing Saturn

Saturn leaves retrograde motion as its 2013 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
Saturn 14h12m40s 10°43'S Virgo 0.3 17.6"

The coordinates above are given in J2000.0.

From Fairfield , it will become visible around 21:08 (EDT), 35° above your southern horizon, as dusk fades to darkness. It will then sink towards the horizon, setting at 01:24.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

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

The sky on 08 July 2013
Sunrise
05:28
Sunset
20:28
Twilight ends
22:36
Twilight begins
03:24

30-day old moon
Waxing Crescent

0%

30 days old

Planets
Rise Culm. Set
Mercury 05:55 13:02 20:10
Venus 07:39 14:50 22:01
Moon 05:57 13:15 20:28
Mars 03:56 11:31 19:05
Jupiter 04:29 12:01 19:32
Saturn 14:34 19:59 01:24
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

28 Apr 2013  –  Saturn at opposition
10 May 2014  –  Saturn at opposition
22 May 2015  –  Saturn at opposition
03 Jun 2016  –  Saturn at opposition

Image credit

© NASA/Cassini

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41.14°N
73.26°W
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