Mars in Retrograde 2018

   From June 26th 2018 to August 27th the planet Mars will be moving backwards or in retrograde motion. 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 moving west from Carpricornus into Sagittarius. Off further west from Mars is the planet Saturn and the reddish star Antares, the “Equal of Mars“. This graphic is set for midway through the retrograde motion on July 26th.
   
   
   star-chart   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.	
Jun 20	20h49m31s	-22°10'29"	-1.8	Capricornus
Jun 22	20h49m53s	-22°13'43"	-1.9	Capricornus
Jun 24	20h50m27s	-22°20'48"	-1.9	Capricornus
Jun 26	20h50m49s	-22°28'42"	-2.0	Capricornus
Jun 28	20h50m59s	-22°37'24"	-2.1	Capricornus
Jun 30	20h50m56s	-22°46'53"	-2.1	Capricornus
Jul 02	20h50m40s	-22°57'06"	-2.2	Capricornus
Jul 04	20h50m12s	-23°08'01"	-2.2	Capricornus
Jul 06	20h49m31s	-23°19'33"	-2.3	Capricornus
Jul 08	20h48m38s	-23°31'39"	-2.4	Capricornus
Jul 10	20h47m32s	-23°44'13"	-2.4	Capricornus
Jul 12	20h46m15s	-23°57'08"	-2.5	Capricornus
Jul 14	20h44m46s	-24°10'18"	-2.5	Capricornus
Jul 16	20h42m14s	-24°30'12"	-2.6	Capricornus
Jul 18	20h41m18s	-24°36'49"	-2.6	Capricornus
Jul 20	20h39m22s	-24°49'55"	-2.7	Capricornus
Jul 22	20h37m18s	-25°02'42"	-2.7	Capricornus
Jul 24	20h35m09s	-25°15'03"	-2.8	Capricornus
Jul 26	20h32m56s	-25°26'52"	-2.8	Capricornus
Jul 28	20h30m40s	-25°37'59"	-2.8	Capricornus
Jul 30	20h28m22s	-25°48'18"	-2.8	Capricornus
Aug 02	20h24m56s	-26°02'06"	-2.8	Capricornus
Aug 04	20h22m42s	-26°10'01"	-2.7	Capricornus
Aug 06	20h20m31s	-26°16'51"	-2.7	Capricornus
Aug 08	20h18m27s	-26°22'32"	-2.7	Capricornus
Aug 10	20h16m28s	-26°27'02"	-2.6	Capricornus
Aug 14	20h12m59s	-26°32'23"	-2.6	Capricornus
Aug 16	20h11m31s	-26°33'14"	-2.5	Capricornus
Aug 18	20h10m14s	-26°32'54"	-2.5	Capricornus
Aug 20	20h09m10s	-26°31'24"	-2.4	Capricornus
Aug 22	20h08m18s	-26°28'47"	-2.4	Capricornus
Aug 24	20h07m41s	-26°25'05"	-2.3	Capricornus
Aug 26	20h07m18s	-26°20'21"	-2.3	Sagittarius
Aug 28	20h07m08s	-26°14'38"	-2.2	Sagittarius
Aug 30	20h07m12s	-26°07'58"	-2.2	Sagittarius
Sep 02	20h07m44s	-25°56'16"	-2.1	Capricornus
Sep 04	20h08m22s	-25°47'23"	-2.0	Capricornus