© NASA/Hubble Space Telescope

Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed

Objects: Mars
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The sky at

2103–2104 apparition of Mars

10 Dec 2103 – Mars enters retrograde motion
16 Jan 2104 – Mars at perigee
19 Jan 2104 – Mars at opposition
27 Feb 2104 – 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:

Mars
24 Nov 2103
10.7"
Mars
22 Dec 2103
13.2"
Mars
19 Jan 2104
14.5"
Mars
16 Feb 2104
12.5"
Mars
15 Mar 2104
9.7"

Observing Mars

Mars leaves retrograde motion as its 2103–2104 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 18:01 (PST), 53° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 20:45, 81° above your southern horizon. It will continue to be observable until around 03:11, when it sinks below 9° 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 table below lists Mars' angular size and brightness at two-week intervals throughout its apparition:

Date Right ascension Declination Angular size Magnitude
10 Nov 210308h20m40s21°14'N9.6”0.0
24 Nov 210308h36m10s20°53'N10.7”-0.3
08 Dec 210308h43m10s21°05'N11.9”-0.6
22 Dec 210308h39m50s21°57'N13.2”-0.9
05 Jan 210408h25m20s23°23'N14.2”-1.2
19 Jan 210408h02m50s24°52'N14.5”-1.4
02 Feb 210407h40m20s25°48'N13.8”-1.1
16 Feb 210407h25m50s26°01'N12.5”-0.7
01 Mar 210407h22m20s25°43'N11.0”-0.3
15 Mar 210407h29m00s25°03'N9.7”0.0
29 Mar 210407h43m20s24°06'N8.6”0.3

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 07h22m10s 25°49'N Gemini -0.4 11.3"

The coordinates above are given in J2000.0.

The sky on 11 Jan 2026

The sky on 11 January 2026
Sunrise
06:56
Sunset
17:01
Twilight ends
18:30
Twilight begins
05:27

23-day old moon
Waning Crescent

31%

23 days old

Planets
Rise Culm. Set
Mercury 06:40 11:33 16:26
Venus 07:06 12:04 17:02
Moon 00:54 06:18 11:36
Mars 06:59 11:56 16:53
Jupiter 16:42 23:49 06:57
Saturn 10:23 16:16 22:10
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

27 Feb 2104  –  Mars ends retrograde motion
13 Jan 2106  –  Mars enters retrograde motion
22 Feb 2106  –  Mars at opposition
22 Feb 2106  –  Mars at perigee

Image credit

© NASA/Hubble Space Telescope

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