© NASA/Hubble Space Telescope

Mars ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed

Objects: Mars
Please wait
Loading 0/4
Click and drag to rotate
Mouse wheel to zoom in/out
Touch with mouse to dismiss
The sky at

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 a planet in the outer solar system. Not drawn to scale.

2033 apparition of Mars

26 May 2033 – Mars enters retrograde motion
27 Jun 2033 – Mars at opposition
05 Jul 2033 – Mars at perigee
01 Aug 2033 – Mars ends retrograde motion

Observing Mars

Mars leaves retrograde motion as its 2033 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 17h56m50s 28°32'S Sagittarius -2.0 19.9"

The coordinates above are given in J2000.0.

From Fairfield , it will be visible in the evening sky, becoming accessible around 20:27 (EDT), 16° above your south-eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 22:06, 20° above your southern horizon. It will continue to be observable until around 01:12, when it sinks below 7° above your south-western horizon.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

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:

06 Jun 2033
04 Jul 2033
01 Aug 2033
29 Aug 2033
26 Sep 2033

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

Date Angular size Mag
23 May 203316.7”-1.5
06 Jun 203319.2”-2.0
20 Jun 203321.3”-2.4
04 Jul 203322.1”-2.5
18 Jul 203321.5”-2.3
01 Aug 203319.9”-2.0
15 Aug 203317.8”-1.6
29 Aug 203315.9”-1.3
12 Sep 203314.1”-1.0
26 Sep 203312.6”-0.7
10 Oct 203311.3”-0.5

The sky on 01 Aug 2033

The sky on 01 August 2033
Twilight ends
Twilight begins

6-day old moon
Waxing Crescent


6 days old

Rise Culm. Set
Mercury 04:19 11:42 19:05
Venus 02:52 10:18 17:44
Moon 11:49 17:34 23:13
Mars 17:55 22:06 02:16
Jupiter 21:16 02:40 08:05
Saturn 03:45 11:12 18:39
All times shown in EDT.


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

05 Jul 2033  –  Mars at perigee
11 Sep 2035  –  Mars at perigee
15 Sep 2035  –  Mars at opposition
11 Nov 2037  –  Mars at perigee

Image credit

© NASA/Hubble Space Telescope






Color scheme