Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

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.

2054–2055 apparition of Mars

08 Nov 2054 – Mars enters retrograde motion
11 Dec 2054 – Mars at perigee
17 Dec 2054 – Mars at opposition
23 Jan 2055 – Mars ends retrograde motion

Observing Mars

Mars leaves retrograde motion as its 2054–2055 apparition comes to an end, although it will remain visible for some weeks in the dusk sky.

Its celestial coordinates as it leaves retrograde motion will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 05h02m30s 25°59'N Taurus -0.7 12.5"

The coordinates above are given in J2000.0.

From Fairfield , it will be visible in the evening sky, becoming accessible around 17:17 (EDT), 45° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 20:42, 74° above your southern horizon. It will continue to be observable until around 03:29, when it sinks below 8° above your north-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 panels below show the month-by-month change in Mars' apparent size in coming weeks, as it recedes from the Earth:

28 Nov 2054
26 Dec 2054
23 Jan 2055
20 Feb 2055
20 Mar 2055

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

Date Angular size Mag
14 Nov 205414.7”-1.2
28 Nov 205416.0”-1.5
12 Dec 205416.4”-1.7
26 Dec 205415.8”-1.6
09 Jan 205514.3”-1.1
23 Jan 205512.5”-0.7
06 Feb 205510.9”-0.3
20 Feb 20559.4”0.1
06 Mar 20558.3”0.4
20 Mar 20557.4”0.7
03 Apr 20556.7”0.9

The sky on 23 Jul 2024

The sky on 23 July 2024
Sunrise
05:37
Sunset
20:17
Twilight ends
22:14
Twilight begins
03:40


Waning Gibbous

91%

18 days old

Planets
Rise Culm. Set
Mercury 08:00 14:43 21:25
Venus 06:45 13:54 21:03
Moon 21:35 02:43 08:00
Mars 01:27 08:44 16:01
Jupiter 02:06 09:30 16:54
Saturn 22:27 04:08 09:48
All times shown in EDT.

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

23 Jan 2055  –  Mars ends retrograde motion
14 Dec 2056  –  Mars enters retrograde motion
21 Jan 2057  –  Mars at perigee
23 Jan 2057  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope

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