© NASA/Hubble Space Telescope

Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed

Objects: Mars
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Mars 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 Mars. Not drawn to scale.

2022–2023 apparition of Mars

30 Oct 2022 – Mars enters retrograde motion
30 Nov 2022 – Mars at perigee
07 Dec 2022 – Mars at opposition
12 Jan 2023 – Mars ends retrograde motion

Observing Mars

Mars leaves retrograde motion as its 2022–2023 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
Mars 04h22m00s 24°24'N Taurus -0.8 13.1"

The coordinates above are given in J2000.0.

From Washington , it will be visible in the evening sky, becoming accessible around 17:56 (MDT), 43° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 21:26, 77° above your southern horizon. It will continue to be observable until around 03:59, when it sinks below 8° above your north-western horizon.

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

The panels below show the month-by-month change in Mars' apparent size in coming weeks, as it recedes from the Earth:

17 Nov 2022
15 Dec 2022
12 Jan 2023
09 Feb 2023
09 Mar 2023

The table below lists Mars' angular size at brightness at two-week intervals throughout its apparition:

Date Angular size Mag
03 Nov 202215.4”-1.3
17 Nov 202216.7”-1.6
01 Dec 202217.2”-1.8
15 Dec 202216.5”-1.7
29 Dec 202215.0”-1.3
12 Jan 202313.1”-0.8
26 Jan 202311.3”-0.4
09 Feb 20239.8”-0.0
23 Feb 20238.6”0.3
09 Mar 20237.6”0.6
23 Mar 20236.8”0.8

The sky on 12 Jan 2023

The sky on 12 January 2023
Twilight ends
Twilight begins

20-day old moon
Waning Gibbous


20 days old

Rise Culm. Set
Mercury 06:49 11:49 16:50
Venus 09:00 14:04 19:08
Moon 22:06 04:43 11:10
Mars 14:02 21:26 04:50
Jupiter 11:13 17:16 23:18
Saturn 09:33 14:49 20:06
All times shown in MST.


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

12 Jan 2023  –  Mars ends retrograde motion
06 Dec 2024  –  Mars enters retrograde motion
12 Jan 2025  –  Mars at perigee
15 Jan 2025  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope





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