Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

2204 apparition of Mars

17 Mar 2204 – Mars enters retrograde motion
23 Apr 2204 – Mars at opposition
30 Apr 2204 – Mars at perigee
03 Jun 2204 – 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:

27 Feb 2204
10.1"
26 Mar 2204
13.3"
23 Apr 2204
15.8"
21 May 2204
14.9"
18 Jun 2204
12.2"

Observing Mars

Mars leaves retrograde motion as its 2204 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 20:06 (PST), 43° above your south-eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 21:20, 47° above your southern horizon. It will continue to be observable until around 02:17, when it sinks below 8° above your 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
13 Feb 220414h09m30s10°45'S8.8”0.3
27 Feb 220414h23m20s11°52'S10.1”-0.1
12 Mar 220414h30m20s12°27'S11.6”-0.5
26 Mar 220414h28m40s12°24'S13.3”-0.9
09 Apr 220414h17m00s11°42'S14.8”-1.3
23 Apr 220413h58m10s10°29'S15.8”-1.6
07 May 220413h38m00s9°13'S15.8”-1.5
21 May 220413h23m40s8°29'S14.9”-1.2
04 Jun 220413h18m50s8°34'S13.6”-0.9
18 Jun 220413h23m30s9°30'S12.2”-0.6
02 Jul 220413h36m20s11°07'S11.0”-0.3

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 13h18m50s 8°31'S Virgo -0.9 13.7"

The coordinates above are given in J2000.0.

The sky on 5 Feb 2026

The sky on 5 February 2026
Sunrise
06:44
Sunset
17:25
Twilight ends
18:51
Twilight begins
05:18


Waning Gibbous

77%

18 days old

Planets
Rise Culm. Set
Mercury 07:24 12:49 18:14
Venus 07:13 12:34 17:56
Moon 20:42 02:47 08:44
Mars 06:29 11:39 16:49
Jupiter 14:49 21:58 05:07
Saturn 08:50 14:46 20:42
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

03 Jun 2204  –  Mars ends retrograde motion
09 May 2206  –  Mars enters retrograde motion
12 Jun 2206  –  Mars at opposition
20 Jun 2206  –  Mars at perigee

Image credit

© NASA/Hubble Space Telescope

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