Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

2150–2151 apparition of Mars

04 Dec 2150 – Mars enters retrograde motion
09 Jan 2151 – Mars at perigee
13 Jan 2151 – Mars at opposition
21 Feb 2151 – 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:

18 Nov 2150
10.9"
16 Dec 2150
13.6"
13 Jan 2151
14.8"
10 Feb 2151
12.6"
10 Mar 2151
9.8"

Observing Mars

Mars leaves retrograde motion as its 2150–2151 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 17:52 (PST), 53° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 20:40, 82° above your southern horizon. It will continue to be observable until around 03:09, when it sinks below 8° above your north-western horizon.

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
04 Nov 215007h53m50s22°18'N9.8”-0.1
18 Nov 215008h09m50s22°05'N10.9”-0.3
02 Dec 215008h17m10s22°20'N12.2”-0.6
16 Dec 215008h13m40s23°11'N13.6”-1.0
30 Dec 215007h58m40s24°31'N14.6”-1.3
13 Jan 215107h35m50s25°50'N14.8”-1.4
27 Jan 215107h13m10s26°36'N14.0”-1.1
10 Feb 215106h58m50s26°43'N12.6”-0.8
24 Feb 215106h55m50s26°24'N11.1”-0.4
10 Mar 215107h03m00s25°50'N9.8”0.0
24 Mar 215107h17m50s25°02'N8.6”0.3

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 06h55m30s 26°30'N Gemini -0.5 11.5"

The coordinates above are given in J2000.0.

The sky on 5 Mar 2026

The sky on 5 March 2026
Sunrise
06:13
Sunset
17:51
Twilight ends
19:14
Twilight begins
04:50


Waning Gibbous

91%

16 days old

Planets
Rise Culm. Set
Mercury 06:09 12:08 18:07
Venus 06:57 12:55 18:53
Moon 19:26 01:22 07:10
Mars 05:45 11:16 16:46
Jupiter 12:51 20:00 03:10
Saturn 07:08 13:08 19:07
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

21 Feb 2151  –  Mars ends retrograde motion
07 Jan 2153  –  Mars enters retrograde motion
16 Feb 2153  –  Mars at perigee
16 Feb 2153  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope

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