Mars 2020 Retrograde Loop

Mars Retrograde Loop
   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 beyond the Earth’s orbit 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 innermost 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 year the planet Mars appears to pause in its orbit on September 9th within the constellation of Pisces the Fishes and then begins moving westward or in retrograde across the constellation of Pisces the Fishes. By Mid-November Mars will have returned to its eastward, or prograde, orbital motion.
   
      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.

   The data tables below show position information about Mars. The first two columns are what will be used for plotting the changing position of Mars. R.A. is the Right Ascension or hour circle position of Mars and is in units of hours and 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.
    Distance is between the Earth and Mars and is shown using AU or Astronomical Units (93,000,000 miles 149,668,992 km). Ang. Diam is the apparent size, or angular diameter, the planet appears and is measured in units of degrees, minutes, and seconds. Scroll down the data to October 6th where you will see when Mars is closest to the Earth as evidenced by having the smallest distance of 0.4149202 AU.

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Coordinate Positions for Mars


 September 2020
Day|       RA        |       Decl      |     Distance    |  Ang Diam  | VMag
 1 |   01h 48m 41.4s |   +6° 38' 48.9" |    0.4941852 AU |  00' 18.9" | -1.8
 2 |   01h 49m 07.4s |   +6° 41' 08.2" |    0.4902798 AU |  00' 19.1" | -1.8
 3 |   01h 49m 30.3s |   +6° 43' 13.7" |    0.4864417 AU |  00' 19.2" | -1.9
 4 |   01h 49m 49.9s |   +6° 45' 05.2" |    0.4826728 AU |  00' 19.4" | -1.9
 5 |   01h 50m 06.3s |   +6° 46' 42.6" |    0.4789754 AU |  00' 19.5" | -1.9
 6 |   01h 50m 19.4s |   +6° 48' 06.0" |    0.4753516 AU |  00' 19.7" | -1.9
 7 |   01h 50m 29.2s |   +6° 49' 15.3" |    0.4718040 AU |  00' 19.8" | -2.0
 8 |   01h 50m 35.6s |   +6° 50' 10.4" |    0.4683349 AU |  00' 20.0" | -2.0
 9 |   01h 50m 38.7s |   +6° 50' 51.5" |    0.4649470 AU |  00' 20.1" | -2.0
10 |   01h 50m 38.3s |   +6° 51' 18.5" |    0.4616430 AU |  00' 20.3" | -2.0
11 |   01h 50m 34.5s |   +6° 51' 31.4" |    0.4584258 AU |  00' 20.4" | -2.1
12 |   01h 50m 27.2s |   +6° 51' 30.4" |    0.4552982 AU |  00' 20.6" | -2.1
13 |   01h 50m 16.4s |   +6° 51' 15.4" |    0.4522635 AU |  00' 20.7" | -2.1
14 |   01h 50m 02.2s |   +6° 50' 46.7" |    0.4493246 AU |  00' 20.8" | -2.1
15 |   01h 49m 44.5s |   +6° 50' 04.4" |    0.4464849 AU |  00' 21.0" | -2.2
16 |   01h 49m 23.3s |   +6° 49' 08.6" |    0.4437477 AU |  00' 21.1" | -2.2
17 |   01h 48m 58.8s |   +6° 47' 59.8" |    0.4411163 AU |  00' 21.2" | -2.2
18 |   01h 48m 30.8s |   +6° 46' 38.1" |    0.4385939 AU |  00' 21.3" | -2.2
19 |   01h 47m 59.5s |   +6° 45' 04.0" |    0.4361836 AU |  00' 21.5" | -2.2
20 |   01h 47m 25.0s |   +6° 43' 17.9" |    0.4338886 AU |  00' 21.6" | -2.3
21 |   01h 46m 47.2s |   +6° 41' 20.3" |    0.4317117 AU |  00' 21.7" | -2.3
22 |   01h 46m 06.4s |   +6° 39' 11.6" |    0.4296557 AU |  00' 21.8" | -2.3
23 |   01h 45m 22.5s |   +6° 36' 52.3" |    0.4277231 AU |  00' 21.9" | -2.3
24 |   01h 44m 35.7s |   +6° 34' 23.0" |    0.4259166 AU |  00' 22.0" | -2.4
25 |   01h 43m 46.0s |   +6° 31' 44.2" |    0.4242385 AU |  00' 22.1" | -2.4
26 |   01h 42m 53.5s |   +6° 28' 56.4" |    0.4226913 AU |  00' 22.1" | -2.4
27 |   01h 41m 58.5s |   +6° 26' 00.2" |    0.4212774 AU |  00' 22.2" | -2.4
28 |   01h 41m 00.9s |   +6° 22' 56.1" |    0.4199990 AU |  00' 22.3" | -2.4
29 |   01h 40m 00.9s |   +6° 19' 44.7" |    0.4188585 AU |  00' 22.3" | -2.5
30 |   01h 38m 58.6s |   +6° 16' 26.7" |    0.4178582 AU |  00' 22.4" | -2.5

Ocober 2020
Day|       RA        |       Decl      |     Distance    |  Ang Diam  | VMag
 1 |   01h 37m 54.2s |   +6° 13' 02.7" |    0.4170002 AU |  00' 22.4" | -2.5
 2 |   01h 36m 47.7s |   +6° 09' 33.5" |    0.4162868 AU |  00' 22.5" | -2.5
 3 |   01h 35m 39.5s |   +6° 05' 59.6" |    0.4157201 AU |  00' 22.5" | -2.5
 4 |   01h 34m 29.5s |   +6° 02' 21.8" |    0.4153021 AU |  00' 22.5" | -2.5
 5 |   01h 33m 18.1s |   +5° 58' 40.9" |    0.4150348 AU |  00' 22.6" | -2.6
 6 |   01h 32m 05.3s |   +5° 54' 57.7" |    0.4149202 AU |  00' 22.6" | -2.6
 7 |   01h 30m 51.3s |   +5° 51' 12.8" |    0.4149601 AU |  00' 22.6" | -2.6
 8 |   01h 29m 36.3s |   +5° 47' 27.2" |    0.4151563 AU |  00' 22.5" | -2.6
 9 |   01h 28m 20.4s |   +5° 43' 41.5" |    0.4155103 AU |  00' 22.5" | -2.6
10 |   01h 27m 04.0s |   +5° 39' 56.8" |    0.4160237 AU |  00' 22.5" | -2.6
11 |   01h 25m 47.1s |   +5° 36' 13.8" |    0.4166979 AU |  00' 22.5" | -2.6
12 |   01h 24m 30.0s |   +5° 32' 33.4" |    0.4175340 AU |  00' 22.4" | -2.6
13 |   01h 23m 12.8s |   +5° 28' 56.4" |    0.4185333 AU |  00' 22.4" | -2.6
14 |   01h 21m 55.8s |   +5° 25' 23.8" |    0.4196965 AU |  00' 22.3" | -2.6
15 |   01h 20m 39.1s |   +5° 21' 56.4" |    0.4210244 AU |  00' 22.2" | -2.6
16 |   01h 19m 23.1s |   +5° 18' 35.3" |    0.4225173 AU |  00' 22.2" | -2.6
17 |   01h 18m 07.8s |   +5° 15' 21.3" |    0.4241753 AU |  00' 22.1" | -2.6
18 |   01h 16m 53.4s |   +5° 12' 15.4" |    0.4259982 AU |  00' 22.0" | -2.5
19 |   01h 15m 40.3s |   +5° 09' 18.3" |    0.4279853 AU |  00' 21.9" | -2.5
20 |   01h 14m 28.5s |   +5° 06' 31.0" |    0.4301358 AU |  00' 21.8" | -2.5
21 |   01h 13m 18.3s |   +5° 03' 54.2" |    0.4324485 AU |  00' 21.6" | -2.5
22 |   01h 12m 09.7s |   +5° 01' 28.5" |    0.4349221 AU |  00' 21.5" | -2.4
23 |   01h 11m 03.0s |   +4° 59' 14.6" |    0.4375552 AU |  00' 21.4" | -2.4
24 |   01h 09m 58.2s |   +4° 57' 13.1" |    0.4403461 AU |  00' 21.3" | -2.4
25 |   01h 08m 55.6s |   +4° 55' 24.4" |    0.4432932 AU |  00' 21.1" | -2.3
26 |   01h 07m 55.2s |   +4° 53' 49.0" |    0.4463948 AU |  00' 21.0" | -2.3
27 |   01h 06m 57.1s |   +4° 52' 27.4" |    0.4496491 AU |  00' 20.8" | -2.3
28 |   01h 06m 01.5s |   +4° 51' 19.9" |    0.4530543 AU |  00' 20.7" | -2.3
29 |   01h 05m 08.4s |   +4° 50' 26.7" |    0.4566085 AU |  00' 20.5" | -2.2
30 |   01h 04m 17.9s |   +4° 49' 48.3" |    0.4603099 AU |  00' 20.3" | -2.2
31 |   01h 03m 30.2s |   +4° 49' 24.8" |    0.4641564 AU |  00' 20.2" | -2.2
 
November 2020
Day|       RA        |       Decl      |     Distance    |  Ang Diam  | VMag
 1 |   01h 02m 45.2s |   +4° 49' 16.5" |    0.4681463 AU |  00' 20.0" | -2.1
 2 |   01h 02m 03.0s |   +4° 49' 23.5" |    0.4722775 AU |  00' 19.8" | -2.1
 3 |   01h 01m 23.6s |   +4° 49' 45.8" |    0.4765481 AU |  00' 19.6" | -2.1
 4 |   01h 00m 47.2s |   +4° 50' 23.7" |    0.4809562 AU |  00' 19.5" | -2.0
 5 |   01h 00m 13.8s |   +4° 51' 17.2" |    0.4854998 AU |  00' 19.3" | -2.0
 6 |   00h 59m 43.3s |   +4° 52' 26.3" |    0.4901771 AU |  00' 19.1" | -2.0
 7 |   00h 59m 15.8s |   +4° 53' 51.0" |    0.4949860 AU |  00' 18.9" | -1.9
 8 |   00h 58m 51.4s |   +4° 55' 31.3" |    0.4999246 AU |  00' 18.7" | -1.9
 9 |   00h 58m 30.0s |   +4° 57' 27.2" |    0.5049911 AU |  00' 18.5" | -1.9
10 |   00h 58m 11.7s |   +4° 59' 38.7" |    0.5101834 AU |  00' 18.3" | -1.8
11 |   00h 57m 56.4s |   +5° 02' 05.6" |    0.5154994 AU |  00' 18.2" | -1.8
12 |   00h 57m 44.3s |   +5° 04' 48.1" |    0.5209372 AU |  00' 18.0" | -1.8
13 |   00h 57m 35.2s |   +5° 07' 46.0" |    0.5264944 AU |  00' 17.8" | -1.7
14 |   00h 57m 29.2s |   +5° 10' 59.3" |    0.5321689 AU |  00' 17.6" | -1.7
15 |   00h 57m 26.2s |   +5° 14' 28.0" |    0.5379582 AU |  00' 17.4" | -1.7
16 |   00h 57m 26.4s |   +5° 18' 11.7" |    0.5438596 AU |  00' 17.2" | -1.6
17 |   00h 57m 29.6s |   +5° 22' 10.6" |    0.5498707 AU |  00' 17.0" | -1.6
18 |   00h 57m 35.8s |   +5° 26' 24.2" |    0.5559886 AU |  00' 16.8" | -1.6
19 |   00h 57m 44.9s |   +5° 30' 52.5" |    0.5622108 AU |  00' 16.6" | -1.5
20 |   00h 57m 57.1s |   +5° 35' 35.1" |    0.5685347 AU |  00' 16.5" | -1.5
21 |   00h 58m 12.1s |   +5° 40' 31.8" |    0.5749577 AU |  00' 16.3" | -1.5
22 |   00h 58m 30.0s |   +5° 45' 42.2" |    0.5814774 AU |  00' 16.1" | -1.4
23 |   00h 58m 50.7s |   +5° 51' 06.2" |    0.5880915 AU |  00' 15.9" | -1.4
24 |   00h 59m 14.2s |   +5° 56' 43.3" |    0.5947978 AU |  00' 15.7" | -1.4
25 |   00h 59m 40.3s |   +6° 02' 33.3" |    0.6015942 AU |  00' 15.6" | -1.3
26 |   01h 00m 09.2s |   +6° 08' 35.8" |    0.6084785 AU |  00' 15.4" | -1.3
27 |   01h 00m 40.7s |   +6° 14' 50.5" |    0.6154490 AU |  00' 15.2" | -1.3
28 |   01h 01m 14.7s |   +6° 21' 17.1" |    0.6225036 AU |  00' 15.0" | -1.2
29 |   01h 01m 51.3s |   +6° 27' 55.3" |    0.6296406 AU |  00' 14.9" | -1.2
30 |   01h 02m 30.4s |   +6° 34' 44.7" |    0.6368584 AU |  00' 14.7" | -1.2
 


   
   
   

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Mars at Opposition

Mars at Opposition
   Sunday May 22nd Mars will reach a point in its orbit around the Sun where it is at opposition relative to the Earth. at opposition The Earth is between the Sun and Mars, or any of the outer planets. At opposition both the Earth and the planet at opposition will have near identical heliocentric longitude. The opposition of Mars sometimes happens around the time that Mars is at its respective perihelion, closest to the Sun. If this happens during or near July when the Earth is at its respective aphelion, furthest from the Sun, then Mars will appear larger relative to when these dates are further apart. However Mars will never be as large as the full Moon, as explained in previous posts: “Mars Closest to Earth this Time”, or “Mars Madness” to read this one.
   The ‘Red Planet’ Mars has been in retrograde Motion since this past April, and will continue to retrograde until the end of June.
   Retrograde motion is the apparent backward, or westward motion that a planet will appear to make at a regular point in its revolution around the Sun.

We typically think of retrograde motion as being done by an outer planet from the Earth. This happens when the faster orbiting Earth catches up and passes by an outer planet. As this is happening the outer planet appears to slow down and then reverse its orbital direction toward the west. After a period of time (days to months) the outer planet again appears to slow down and then return to its regular eastward, or direct motion.
An inner planet orbit    However the two inner planets Mercury and Venus also undergo retrograde motion. Approximately one-half of their respective orbits is eastward as is with all the other planets. This then brings the inner planets to what is know as eastern elongation in the evening skies. The other half of the orbit for Mercury and Venus is toward the west as they move from eastern elongation through inferior conjunction toward western elongation in the morning skies.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mars Meets Its Equal

   This morning Mars was less than 1o from the 2nd magnitude star Graffias, one of the stars marking the pincers of Scorpius the Scorpion. Over the next several days Mars will continue moving along its orbit toward the east coming closer to the planet Saturn, and the ‘rival of Mars’, the heart of the scorpion, the reddish star Antares.
   Antares owes its name to its near matching color of the reddish colored planet Mars. I have often described the name Antares origin as meaning ‘anti mars’, to distinguish the star from the planet. Sort of like saying at times like now when they are close that ‘that reddish object is not Mars’. However the name Antares from the Greek really means ‘equal to Mars’
   This part of the sky, the summer sky for the northern hemisphere, has probably the best view of the Milky Way so it is with a great deal of excitement that as Mars approaches Antares and Saturn Mars is moving closer to the Milky Way. However as this graphic shows the path of Mars takes an expected turn, so to speak, as Mars begins its retrograde motion on April 17th.

Follow the 2016 Retrograde Motion of Mars.

   
   
   
   

Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mars Ends Retrograde Motion

Click on graphic to see it full size.

Click on graphic to see it full size.

   Since the first of this past March the ‘red planet’ (love saying that!!) Mars has been moving in retrograde near the star Spica in Virgo. Retrograde, or retrograde motion, is an apparent reversal of an outer planet or dwarf planet’s regular orbital motion eastward around the Sun – as viewed from Earth. On Wednesday 21 May Mars ends its retrograde motion and resumes its regular or direct motion (eastward). Mars is also recently past opposition in April and so it is still near its maximum apparent magnitude (brightness) of -0.75. Nearby, for comparison, is the 3rd magnitude star Porrima.
Read more about the retrograde motion of Mars in a previous blog.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

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The 2014 MaRetrograde Motion

The 2014 Mars Retrograde Motion

   The ‘Red Planet’ Mars begins its retrograde Motion today. Retrograde motion is the apparent backward, or westward motion that a planet will appear to make at a regular point in its revolution around the Sun. We typically think of retrograde motion as being done by an outer planet from the Earth. This happens when the faster orbiting Earth catches up and passes by an outer planet. As this is happening the outer planet appears to slow down and then reverse its orbital direction toward the west. After a period of time (days to months) the outer planet again appears to slow down and then return to its regular eastward, or direct motion.
An inner planet orbit

An Inner Planet Orbit

   However the two inner planets Mercury and Venus also undergo retrograde motion. Approximately one-half of their respective orbits is eastward as is with all the other planets. This then brings the inner planets to what is know as eastern elongation in the evening skies. The other half of the orbit for Mercury and Venus is toward the west as they move from eastern elongation through inferior conjunction toward western elongation in the morning skies.

Coordinate Positions for Mars

 Date             RA	    Dec
  		 h  m  	  deg  m          
Feb  4		13 32	  -6 54
Feb 14		13 40	  -7 34
Feb 24  	13 45 	  -7 55
Mar  6  	13 45 	  -7 53
Mar 16  	13 41 	  -7 27
Mar 26  	13 32 	  -6 39
Apr  5  	13 19 	  -5 35
Apr 15  	13 04 	  -4 26
Apr 25  	12 51 	  -3 27
May  5  	12 40 	  -2 50
May 15  	12 35 	  -2 43
May 25  	12 34 	  -3 05
Jun 4  		12 38 	  -3 53
Jun 14  	12 46 	  -5 02
Jun 24  	12 57 	  -6 29

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.