Mars enters retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

2270 apparition of Mars

09 Jun 2270 – Mars enters retrograde motion
11 Jul 2270 – Mars at opposition
17 Jul 2270 – Mars at perigee
13 Aug 2270 – 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:

16 May 2270
13.9"
13 Jun 2270
18.8"
11 Jul 2270
22.7"
08 Aug 2270
21.3"
05 Sep 2270
17.1"

Observing Mars

Mars enters retrograde motion as its 2270 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 23:14, when it reaches an altitude of 7° above your south-eastern horizon. It will then reach its highest point in the sky at 03:14, 30° above your southern horizon. It will be lost to dawn twilight around 05:07, 25° above your south-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
02 May 227018h57m40s23°52'S12.0”-0.6
16 May 227019h17m00s24°01'S13.9”-1.0
30 May 227019h29m30s24°27'S16.3”-1.4
13 Jun 227019h32m50s25°19'S18.8”-1.9
27 Jun 227019h25m30s26°35'S21.2”-2.3
11 Jul 227019h09m50s27°53'S22.7”-2.6
25 Jul 227018h52m20s28°40'S22.7”-2.5
08 Aug 227018h41m50s28°46'S21.3”-2.2
22 Aug 227018h42m50s28°19'S19.3”-1.9
05 Sep 227018h55m30s27°29'S17.1”-1.5
19 Sep 227019h17m10s26°18'S15.1”-1.2

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 19h33m00s 25°04'S Sagittarius -1.8 18.2"

The coordinates above are given in J2000.0.

The sky on 25 Feb 2026

The sky on 25 February 2026
Sunrise
06:23
Sunset
17:44
Twilight ends
19:07
Twilight begins
05:00


Waxing Gibbous

74%

9 days old

Planets
Rise Culm. Set
Mercury 06:55 12:56 18:57
Venus 07:03 12:50 18:37
Moon 11:41 19:21 03:00
Mars 05:59 11:23 16:47
Jupiter 13:23 20:33 03:42
Saturn 07:37 13:36 19:34
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

09 Jun 2270  –  Mars enters retrograde motion
11 Jul 2270  –  Mars at opposition
17 Jul 2270  –  Mars at perigee
13 Aug 2270  –  Mars ends retrograde motion

Image credit

© NASA/Hubble Space Telescope

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