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:
1987 apparition of Saturn
|31 Mar 1987||–||Saturn enters retrograde motion|
|09 Jun 1987||–||Saturn at opposition|
|19 Aug 1987||–||Saturn ends retrograde motion|
Saturn leaves retrograde motion as its 1987 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|
The coordinates above are given in J2000.0.
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 28 November 2021|
24 days old
All times shown in EST.
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.
|09 Jun 1987||– Saturn at opposition|
|20 Jun 1988||– Saturn at opposition|
|02 Jul 1989||– Saturn at opposition|
|14 Jul 1990||– Saturn at opposition|