Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

2208 apparition of Mars

24 Jul 2208 – Mars enters retrograde motion
24 Aug 2208 – Mars at opposition
24 Aug 2208 – Mars at perigee
22 Sep 2208 – 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:

29 Jun 2208
16.8"
27 Jul 2208
22.0"
24 Aug 2208
25.1"
21 Sep 2208
22.0"
19 Oct 2208
16.7"

Observing Mars

Mars leaves retrograde motion as its 2208 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 18:57 (PST), 16° above your south-eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 22:34, 37° above your southern horizon. It will continue to be observable until around 02:58, when it sinks below 7° above your south-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
15 Jun 220821h51m20s16°37'S14.5”-1.1
29 Jun 220822h11m40s15°42'S16.8”-1.5
13 Jul 220822h25m10s15°24'S19.4”-1.9
27 Jul 220822h29m50s15°54'S22.0”-2.3
10 Aug 220822h24m30s17°04'S24.2”-2.7
24 Aug 220822h11m40s18°23'S25.1”-2.9
07 Sep 220821h57m40s19°05'S24.2”-2.7
21 Sep 220821h50m10s18°44'S22.0”-2.3
05 Oct 220821h52m20s17°23'S19.3”-1.9
19 Oct 220822h03m50s15°18'S16.7”-1.5
02 Nov 220822h22m30s12°38'S14.4”-1.1

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 21h49m50s 18°37'S Capricornus -2.3 21.7"

The coordinates above are given in J2000.0.

The sky on 8 Jan 2026

The sky on 8 January 2026
Sunrise
06:56
Sunset
16:58
Twilight ends
18:27
Twilight begins
05:27


Waning Gibbous

64%

20 days old

Planets
Rise Culm. Set
Mercury 06:32 11:24 16:16
Venus 07:03 12:00 16:56
Moon 21:58 04:13 10:19
Mars 07:02 11:58 16:54
Jupiter 16:59 00:07 07:14
Saturn 10:34 16:27 22:21
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

22 Sep 2208  –  Mars ends retrograde motion
01 Oct 2210  –  Mars enters retrograde motion
28 Oct 2210  –  Mars at perigee
06 Nov 2210  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope

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