Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

1992–1993 apparition of Mars

28 Nov 1992 – Mars enters retrograde motion
03 Jan 1993 – Mars at perigee
07 Jan 1993 – Mars at opposition
14 Feb 1993 – Mars ends retrograde motion

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.

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

12 Nov 1992
11.1"
10 Dec 1992
13.7"
07 Jan 1993
14.9"
04 Feb 1993
12.7"
04 Mar 1993
9.8"

Observing Mars

Mars leaves retrograde motion as its 1992–1993 apparition comes to an end, although it will remain visible for some weeks in the dusk sky.

As retrograde motion ends, it will be visible in the evening sky, becoming accessible around 17:57 (PDT), 52° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 20:50, 82° above your southern horizon. It will continue to be observable until around 03:20, when it sinks below 8° above your north-western horizon.

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

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

Date Right ascension Declination Angular size Magnitude
29 Oct 199207h37m30s22°46'N10.0”-0.1
12 Nov 199207h53m40s22°38'N11.1”-0.4
26 Nov 199208h01m00s22°56'N12.4”-0.7
10 Dec 199207h57m30s23°46'N13.7”-1.0
24 Dec 199207h42m20s25°02'N14.7”-1.3
07 Jan 199307h19m20s26°15'N14.9”-1.5
21 Jan 199306h56m30s26°54'N14.1”-1.2
04 Feb 199306h42m20s26°58'N12.7”-0.8
18 Feb 199306h39m30s26°41'N11.2”-0.4
04 Mar 199306h47m00s26°11'N9.8”-0.0
18 Mar 199307h02m10s25°30'N8.6”0.3

As it leaves retrograde motion, its celestial coordinates will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 06h39m10s 26°47'N Gemini -0.5 11.6"

The coordinates above are given in J2000.0.

The sky on 12 Mar 2026

The sky on 12 March 2026
Sunrise
07:04
Sunset
18:56
Twilight ends
20:20
Twilight begins
05:41


Waning Crescent

29%

24 days old

Planets
Rise Culm. Set
Mercury 06:27 12:17 18:07
Venus 07:51 13:59 20:07
Moon 03:14 07:53 12:34
Mars 06:33 12:09 17:45
Jupiter 13:23 20:33 03:42
Saturn 07:43 13:43 19:44
All times shown in PDT.

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

14 Feb 1993  –  Mars ends retrograde motion
02 Jan 1995  –  Mars enters retrograde motion
11 Feb 1995  –  Mars at perigee
11 Feb 1995  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope

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