Mars enters retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

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.

2061 apparition of Mars

22 Feb 2061 – Mars enters retrograde motion
02 Apr 2061 – Mars at opposition
07 Apr 2061 – Mars at perigee
13 May 2061 – Mars ends retrograde motion

Observing Mars

Mars enters retrograde motion as its 2061 apparition gets underway, although it has already been visible for some weeks in the pre-dawn sky.

Its celestial coordinates as it enters retrograde motion will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 13h22m50s 5°27'S Virgo -0.4 11.5"

The coordinates above are given in J2000.0.

From Fairfield , it will be visible in the morning sky, becoming accessible around 22:14, when it reaches an altitude of 9° above your eastern horizon. It will then reach its highest point in the sky at 03:04, 43° above your southern horizon. It will be lost to dawn twilight around 06:10, 26° 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 panels below show the month-by-month change in Mars' apparent size in coming weeks:

28 Dec 2060
25 Jan 2061
22 Feb 2061
22 Mar 2061
19 Apr 2061

The table below lists Mars' angular size at brightness at two-week intervals throughout its apparition:

Date Angular size Mag
14 Dec 20606.3”1.0
28 Dec 20607.0”0.8
11 Jan 20617.8”0.6
25 Jan 20618.8”0.3
08 Feb 206110.0”-0.1
22 Feb 206111.4”-0.4
08 Mar 206113.0”-0.8
22 Mar 206114.2”-1.2
05 Apr 206114.8”-1.4
19 Apr 206114.5”-1.2
03 May 206113.4”-0.9

The sky on 24 Nov 2024

The sky on 24 November 2024
Sunrise
06:49
Sunset
16:27
Twilight ends
18:04
Twilight begins
05:12


Waning Crescent

26%

23 days old

Planets
Rise Culm. Set
Mercury 08:34 13:01 17:28
Venus 10:14 14:42 19:09
Moon 00:22 06:55 13:17
Mars 20:46 04:08 11:31
Jupiter 17:18 00:45 08:11
Saturn 13:01 18:33 00:05
All times shown in EST.

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 Feb 2061  –  Mars enters retrograde motion
02 Apr 2061  –  Mars at opposition
07 Apr 2061  –  Mars at perigee
13 May 2061  –  Mars ends retrograde motion

Image credit

© NASA/Hubble Space Telescope

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