Mars enters retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

2217 apparition of Mars

24 Jan 2217 – Mars enters retrograde motion
04 Mar 2217 – Mars at opposition
06 Mar 2217 – Mars at perigee
15 Apr 2217 – 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:

07 Jan 2217
9.6"
04 Feb 2217
12.2"
04 Mar 2217
13.9"
01 Apr 2217
12.5"
29 Apr 2217
10.0"

Observing Mars

Mars enters retrograde motion as its 2217 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 21:36, when it reaches an altitude of 9° above your eastern horizon. It will then reach its highest point in the sky at 03:09, 62° above your southern horizon. It will be lost to dawn twilight around 06:18, 38° 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
24 Dec 221611h12m10s8°06'N8.5”0.3
07 Jan 221711h25m20s7°08'N9.6”0.0
21 Jan 221711h31m30s6°55'N10.8”-0.3
04 Feb 221711h28m50s7°38'N12.2”-0.7
18 Feb 221711h16m40s9°12'N13.3”-1.0
04 Mar 221710h57m10s11°12'N13.9”-1.2
18 Mar 221710h36m50s12°54'N13.5”-1.0
01 Apr 221710h22m30s13°43'N12.5”-0.7
15 Apr 221710h17m20s13°34'N11.2”-0.4
29 Apr 221710h21m10s12°35'N10.0”-0.1
13 May 221710h32m30s10°59'N9.0”0.2

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 11h31m40s 6°58'N Leo -0.3 11.0"

The coordinates above are given in J2000.0.

The sky on 6 Feb 2026

The sky on 6 February 2026
Sunrise
06:43
Sunset
17:26
Twilight ends
18:52
Twilight begins
05:17


Waning Gibbous

72%

19 days old

Planets
Rise Culm. Set
Mercury 07:25 12:52 18:19
Venus 07:13 12:35 17:58
Moon 21:42 03:30 09:09
Mars 06:28 11:39 16:49
Jupiter 14:44 21:53 05:02
Saturn 08:46 14:43 20:39
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

24 Jan 2217  –  Mars enters retrograde motion
04 Mar 2217  –  Mars at opposition
06 Mar 2217  –  Mars at perigee
15 Apr 2217  –  Mars ends retrograde motion

Image credit

© NASA/Hubble Space Telescope

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