© 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

2054–2055 apparition of Mars

08 Nov 2054 – Mars enters retrograde motion
11 Dec 2054 – Mars at perigee
17 Dec 2054 – Mars at opposition
23 Jan 2055 – 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
22 Oct 2054
12.4"
Mars
19 Nov 2054
15.3"
Mars
17 Dec 2054
16.3"
Mars
14 Jan 2055
13.6"
Mars
11 Feb 2055
10.3"

Observing Mars

Mars leaves retrograde motion as its 2054–2055 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 17:30 (PST), 48° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 20:40, 81° above your southern horizon. It will continue to be observable until around 03:10, 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 table below lists Mars' angular size and brightness at two-week intervals throughout its apparition:

Date Right ascension Declination Angular size Magnitude
08 Oct 205405h56m40s23°22'N11.2”-0.4
22 Oct 205406h14m10s23°49'N12.4”-0.7
05 Nov 205406h22m10s24°21'N13.9”-1.0
19 Nov 205406h18m40s25°04'N15.3”-1.3
03 Dec 205406h03m00s25°50'N16.3”-1.6
17 Dec 205405h39m30s26°18'N16.3”-1.7
31 Dec 205405h17m30s26°19'N15.3”-1.4
14 Jan 205505h04m40s26°06'N13.6”-1.0
28 Jan 205505h03m30s25°56'N11.8”-0.5
11 Feb 205505h12m30s25°55'N10.3”-0.1
25 Feb 205505h29m10s25°57'N9.0”0.2

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 05h02m30s 25°59'N Taurus -0.7 12.5"

The coordinates above are given in J2000.0.

The sky on 9 Jan 2026

The sky on 9 January 2026
Sunrise
06:56
Sunset
16:59
Twilight ends
18:28
Twilight begins
05:27

20-day old moon
Waning Gibbous

57%

20 days old

Planets
Rise Culm. Set
Mercury 06:35 11:27 16:19
Venus 07:04 12:01 16:58
Moon 22:58 04:55 10:44
Mars 07:01 11:58 16:54
Jupiter 16:55 00:02 07:09
Saturn 10:30 16:24 22:17
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

23 Jan 2055  –  Mars ends retrograde motion
14 Dec 2056  –  Mars enters retrograde motion
21 Jan 2057  –  Mars at perigee
23 Jan 2057  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope

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