© 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

2086–2087 apparition of Mars

17 Nov 2086 – Mars enters retrograde motion
21 Dec 2086 – Mars at perigee
26 Dec 2086 – Mars at opposition
02 Feb 2087 – 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
31 Oct 2086
11.9"
Mars
28 Nov 2086
14.6"
Mars
26 Dec 2086
15.7"
Mars
23 Jan 2087
13.2"
Mars
20 Feb 2087
10.0"

Observing Mars

Mars leaves retrograde motion as its 2086–2087 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 17:39 (PST), 50° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 20:39, 82° 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
17 Oct 208606h38m20s23°39'N10.7”-0.3
31 Oct 208606h55m20s23°51'N11.9”-0.6
14 Nov 208607h03m10s24°17'N13.2”-0.9
28 Nov 208606h59m30s25°04'N14.6”-1.2
12 Dec 208606h43m50s26°03'N15.6”-1.5
26 Dec 208606h20m20s26°50'N15.7”-1.6
09 Jan 208705h57m50s27°06'N14.8”-1.3
23 Jan 208705h44m20s26°58'N13.2”-0.9
06 Feb 208705h42m30s26°43'N11.5”-0.5
20 Feb 208705h51m00s26°29'N10.0”-0.1
06 Mar 208706h07m10s26°12'N8.8”0.3

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 05h41m50s 26°48'N Taurus -0.6 12.1"

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

35%

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

02 Feb 2087  –  Mars ends retrograde motion
22 Dec 2088  –  Mars enters retrograde motion
29 Jan 2089  –  Mars at perigee
31 Jan 2089  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope

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