Mars enters retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

1967 apparition of Mars

08 Mar 1967 – Mars enters retrograde motion
15 Apr 1967 – Mars at opposition
21 Apr 1967 – Mars at perigee
26 May 1967 – 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:

18 Feb 1967
10.0"
18 Mar 1967
13.1"
15 Apr 1967
15.5"
13 May 1967
14.5"
10 Jun 1967
11.9"

Observing Mars

Mars enters retrograde motion as its 1967 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 22:11, when it reaches an altitude of 8° above your eastern horizon. It will then reach its highest point in the sky at 02:59, 45° above your southern horizon. It will be lost to dawn twilight around 05:53, 29° 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
04 Feb 196713h48m20s8°38'S8.7”0.3
18 Feb 196714h01m50s9°45'S10.0”-0.1
04 Mar 196714h08m40s10°17'S11.4”-0.4
18 Mar 196714h06m50s10°07'S13.1”-0.8
01 Apr 196713h55m20s9°15'S14.6”-1.2
15 Apr 196713h36m40s7°52'S15.5”-1.6
29 Apr 196713h16m40s6°29'S15.4”-1.4
13 May 196713h02m20s5°42'S14.5”-1.1
27 May 196712h57m20s5°48'S13.2”-0.8
10 Jun 196713h01m40s6°46'S11.9”-0.5
24 Jun 196713h14m00s8°27'S10.7”-0.3

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 14h09m10s 10°18'S Virgo -0.6 11.9"

The coordinates above are given in J2000.0.

The sky on 30 Jan 2026

The sky on 30 January 2026
Sunrise
06:48
Sunset
17:19
Twilight ends
18:46
Twilight begins
05:22


Waxing Gibbous

98%

12 days old

Planets
Rise Culm. Set
Mercury 07:18 12:32 17:45
Venus 07:14 12:28 17:43
Moon 15:01 22:35 06:01
Mars 06:37 11:44 16:50
Jupiter 15:16 22:24 05:33
Saturn 09:12 15:08 21:03
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

08 Mar 1967  –  Mars enters retrograde motion
15 Apr 1967  –  Mars at opposition
21 Apr 1967  –  Mars at perigee
26 May 1967  –  Mars ends retrograde motion

Image credit

© NASA/Hubble Space Telescope

Share