Mars enters retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

2071–2072 apparition of Mars

01 Dec 2071 – Mars enters retrograde motion
06 Jan 2072 – Mars at perigee
10 Jan 2072 – Mars at opposition
18 Feb 2072 – Mars ends retrograde motion

Mars will enter retrograde motion, halting its usual eastward movement through the constellations, and turning to move westwards instead. This reversal of direction is a phenomenon that all the solar system's outer planets periodically undergo, a few months before they reach 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:

15 Nov 2071
11.0"
13 Dec 2071
13.7"
10 Jan 2072
14.8"
07 Feb 2072
12.7"
06 Mar 2072
9.8"

Observing Mars

Mars enters retrograde motion as its 2071–2072 apparition gets underway, although it has already been visible for some weeks in the pre-dawn sky.

As retrograde motion starts, it will be visible in the morning sky, becoming accessible around 20:59, when it reaches an altitude of 8° above your eastern horizon. It will then reach its highest point in the sky at 03:19, 78° above your southern horizon. It will be lost to dawn twilight around 06:14, 50° above your western horizon.

Over the following weeks, Mars will reach its highest point in the sky four minutes earlier each night, gradually becoming visible in the evening sky, as well as the pre-dawn sky, as it approaches opposition.

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

Date Right ascension Declination Angular size Magnitude
01 Nov 207107h45m40s22°33'N9.9”-0.1
15 Nov 207108h01m40s22°23'N11.0”-0.4
29 Nov 207108h09m00s22°39'N12.3”-0.7
13 Dec 207108h05m30s23°30'N13.7”-1.0
27 Dec 207107h50m30s24°48'N14.6”-1.3
10 Jan 207207h27m30s26°03'N14.8”-1.4
24 Jan 207207h04m50s26°46'N14.1”-1.2
07 Feb 207206h50m30s26°51'N12.7”-0.8
21 Feb 207206h47m40s26°33'N11.2”-0.4
06 Mar 207206h55m00s26°01'N9.8”0.0
20 Mar 207207h10m00s25°17'N8.6”0.3

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 08h09m10s 22°44'N Cancer -0.7 12.5"

The coordinates above are given in J2000.0.

The sky on 1 Mar 2026

The sky on 1 March 2026
Sunrise
06:18
Sunset
17:47
Twilight ends
19:11
Twilight begins
04:55


Waxing Gibbous

98%

12 days old

Planets
Rise Culm. Set
Mercury 06:34 12:35 18:37
Venus 07:00 12:53 18:46
Moon 16:16 23:08 05:50
Mars 05:52 11:19 16:47
Jupiter 13:07 20:16 03:26
Saturn 07:23 13:22 19:21
All times shown in PST.

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

01 Dec 2071  –  Mars enters retrograde motion
06 Jan 2072  –  Mars at perigee
10 Jan 2072  –  Mars at opposition
18 Feb 2072  –  Mars ends retrograde motion

Image credit

© NASA/Hubble Space Telescope

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