About every 26 months, 780 days, the planet Mars appears to pause in its eastward orbital motion and for a period of time, about 72 days, move toward the west before again pausing and returning to its eastward orbital motion. This is known as retrograde motion, and is an apparent, not actual, motion that all planets undergo relative to the Earth’s orbital motion. All outer planets, dwarf planets, and asteroids will have a retrograde motion period each time the Earth moves past them. Picture two race cars circling a track. The inner most car, moving faster, passes the outer car and from the perspective of the inner car it could look like the slower moving car was moving backward.
   This particular retrograde motion has Mars approach the planet Saturn and the reddish star Antares, the “Equal of Mars“.
   
   
      You could plot the retrograde motion of Mars on this equatorial star chart. It is part of a set of free star charts made available from the Department of Physics and Astronomy at Stephen F. Austin State University.
   R.A. is the Right Ascension or hour circle position of Mars and is in units of hours minutes. This is similar to meridians of longitude on Earth except they are numbered from 0 to 23 and there is only east. Dec is the Declination of Mars and is degrees and minutes. Declination is like latitude with degrees north and south from the celestial equator.

   
   
Coordinate Positions for Mars

 Date	   Right      Declination    Approx	Constellation
         Ascension	              Mag.	
Mar. 31	 16h21m49s     -20°37'48"    -0.9	Scorpius
Apr. 08	 16h26m02s     -20°57'38"    -1.1	Ophiuchus
     15	 16h27m58s     -21°14'11"    -1.3	Ophiuchus
     22	 16h27m27s     -21°27'32"    -1.4	Ophiuchus
May  01	 16h22m53s     -21°39'27"    -1.7	Scorpius
     08	 16h16m22s     -21°43'44"    -1.8	Scorpius
     15	 16h07m38s     -21°42'55"    -1.9	Scorpius
     22	 15h57m29s     -21°36'59"    -2.0	Scorpius
Jun  01	 15h42m27s     -21°21'46"    -2.1	Libra
     08	 15h33m03s     -21°09'38"    -2.0	Libra
     15	 15h25m41s     -21°00'01"    -2.0	Libra
     22	 15h20m54s     -20°55'46"    -1.9	Libra
Jul  01	 15h18m54s     -21°00'51"    -1.8	Libra
     08	 15h20m33s     -21°13'42"    -1.6	Libra
     15	 15h24m53s     -21°33'57"    -1.5	Libra
     22	 15h31m37s     -22°00'23"    -1.4	Libra
Aug  01	 15h44m56s     -22°45'34"    -1.2	Libra
     08	 15h56m33s     -23°20'01"    -1.1	Scorpius