Mars Oppositions

Mars Oppositions occur when planet Earth, on its inner orbit, passes between the Sun and planet Mars. Because of the orbits of the two planets, this occurs about every 2 years and 2 months (26 months); the acurate average is the synodic period of 779.94 days. After that period of time, the Earth has moved around the sun exactly one time more than Mars, or 2.135311456 times, while Mars completed 1.135311456 revolutions, so that Earth and Mars are again in a line from the Sun. This line, however, is advanced at an angle of 48.71212423 degrees along the planetary orbits w.r.t. the previous opposition, i.e., in ecliptical longitude.

About at these times, the planets have their closest encounter, but because of the orbital geometry (excentric elliptical orbits and orbital inclination), the exact dates may be separated by a few days. A further disturbation comes from the influence of the Moon which makes Earth move around the common center of mass, and makes it being a bit early or late, a bit closer or more remote than just this center of mass.

Also because of the orbital geometry, in particular the comparatively high excentricity of Mars' orbit and the resulting variations in its orbital and angular velocity, the intervals between consecutive oppositions vary, perihelic oppositions (when Mars is near its perihelion, resulting in close approaches) are less frequent than aphelic oppositions (with Mars near its aphelion, less close encounters).

After 7 oppositions or about 15 (actually 14.95) [Earth] years (7.95 or almost eight Martian revolutions or Mars years), this angle has summed up to 340.985 degrees, so that the 7th opposition is only 19.0 degrees in ecliptical longitude away from (behind) the original one, and occurs about 19 [Earth] days earlier in that year. After 15 oppositions or about 32 (32.03) [Earth] years (17.03 Mars years), the opposition will occur 10.6 degrees after the original one, and happen about 11 days later in that year. After 22 periods (46.977 Earth years, 24.977 Mars years), the opposition will happen 8.3 deg or 8.5 days before the original date. After an interval of 37 synodic periods (79.0065 Earth or 42.0065 Mars years), opposition will occur only 2.35 deg or 2.38 days after the original one, less than one percent of the revolution angle (of 360 deg). Another close hit will occur after 96 synodic periods (204.990 Earth or 108.990 Mars revolutions) when the opposition occurs 3.63 deg or 3.69 days before the first opposition date. Even closer hits will be after 133 synodic periods (283.996 Earth years, 150.996 Mars years) at 1.29 deg or 1.31 days before the first opposition date, and after 170 periods (363.0029 Earth and 193.0029 Mars years) at 1.06 deg, 1.08 days. Eventually, after 303 synodic periods (when Earth has moved 646.9994 times and Mars 343.9994 times around the Sun), opposition will occur only 0.226 degrees or 0.229 days (5 1/2 hours!) earlier than the originally considered opposition.

The following table summarizes these results (note that the number of oppositions is always the difference between Earth and Mars revolutions, or "years", by definition):

Opps E'yr M'yr    deg      days

   1    2    1  +48.712  +49.423
   7   15    8  -19.015  -19.293
  15   32   17  +10.681  +10.836
  22   47   25  - 8.333  - 8.455
  37   79   42  + 2.349  + 2.383
  96  205  109  - 3.636  - 3.689
 133  284  151  - 1.287  - 1.306
 170  363  193  + 1.061  + 1.076
 303  647  344  - 0.226  - 0.229

After all, over periods of centuries, the perihelion of Mars slowly shifts, an effect that must be considered for predicting distances.

Mars Opposition Catalog

Opposition                                 Closest Approach
   Date      UT     L_hel   RA    Dec  m_max    Date      UT   dist AU   Mkm  diam

1950 Mar 23 05:37  182:44 12:13 +02:20 -1.33 1950 Mar 27 06:15 0.64971  97.20 14.41
1952 May  1 01:25  221:17 14:34 -14:17 -1.78 1952 May  8 13:31 0.55824  83.51 16.77
1954 Jun 24 17:14  273:16 18:12 -27:41 -2.49 1954 Jul  2 08:01 0.42779  64.00 21.88
1956 Sep 10 21:51  348:45 23:26 -10:07 -2.85 1956 Sep  7 04:54 0.37809  56.56 24.76
1958 Nov 16 14:26   54:19 03:25 +19:08 -2.19 1958 Nov  8 13:15 0.48770  72.96 19.19
1960 Dec 30 10:14   99:17 06:39 +26:49 -1.55 1960 Dec 25 05:46 0.60682  90.78 15.42
1963 Feb  4 11:50  135:28 09:15 +20:42 -1.25 1963 Feb  3 03:23 0.67045 100.30 13.96
1965 Mar  9 12:22  169:13 11:25 +08:08 -1.25 1965 Mar 12 01:13 0.66847 100.00 14.00
1967 Apr 15 11:24  205:16 13:35 -07:43 -1.56 1967 Apr 21 17:39 0.60120  89.94 15.57
1969 May 31 15:50  250:26 16:32 -23:56 -2.19 1969 Jun  9 04:15 0.47955  71.74 19.52
1971 Aug 10 06:52  317:24 21:27 -22:15 -2.85 1971 Aug 12 02:32 0.37569  56.20 24.91
1973 Oct 25 03:28   31:56 02:00 +10:17 -2.49 1973 Oct 17 04:11 0.43604  65.23 21.47
1975 Dec 15 13:59   83:18 05:29 +26:02 -1.76 1975 Dec  9 00:09 0.56549  84.60 16.55
1978 Jan 22 00:11  121:55 08:20 +24:06 -1.33 1978 Jan 19 03:07 0.65319  97.72 14.33
1980 Feb 25 05:43  156:04 10:37 +13:27 -1.22 1980 Feb 26 06:06 0.67731 101.32 13.83
1982 Mar 31 10:14  190:38 12:43 -01:21 -1.40 1982 Apr  5 06:36 0.63511  95.01 14.75
1984 May 11 08:52  231:04 15:13 +18:05 -1.92 1984 May 19 10:44 0.53146  79.51 17.63
1986 Jul 10 05:27  287:52 19:20 -27:44 -2.65 1986 Jul 16 10:59 0.40357  60.37 23.21
1988 Sep 28 03:32    5:23 00:27 -02:06 -2.75 1988 Sep 22 03:19 0.39315  58.81 23.83
1990 Nov 27 20:35   65:20 04:13 +22:38 -2.02 1990 Nov 20 03:50 0.51692  77.33 18.12
1993 Jan  7 22:43  107:40 07:19 +26:16 -1.46 1993 Jan  3 13:33 0.62609  93.66 14.96
1995 Feb 12 02:32  142:54 09:47 +18:10 -1.23 1995 Feb 11 14:20 0.67569 101.08 13.86
1997 Mar 17 07:55  176:46 11:54 +04:40 -1.29 1997 Mar 20 16:51 0.65938  98.64 14.20
1999 Apr 24 17:38  214:06 14:09 -11:37 -1.67 1999 May  1 17:28 0.57846  86.54 16.18
2001 Jun 13 17:59  262:46 17:28 -26:30 -2.36 2001 Jun 21 22:57 0.45017  67.34 20.79

2003 Aug 28 17:59  335:01 22:38 -15:49 -2.88 2003 Aug 27 09:52 0.37272  55.76 25.11

2005 Nov  7 07:59   45:01 02:51 +15:54 -2.33 2005 Oct 30 03:26 0.46406  69.42 20.19
2007 Dec 24 19:47   92:46 06:12 +26:46 -1.64 2007 Dec 18 23:47 0.58935  88.17 15.88
2010 Jan 29 19:37  129:39 08:54 +22:09 -1.28 2010 Jan 27 19:02 0.66398  99.33 14.10
2012 Mar  3 20:04  163:29 11:07 +10:17 -1.23 2012 Mar  5 17:01 0.67368 100.78 13.89
2014 Apr  8 20:57  198:44 13:14 -05:08 -1.48 2014 Apr 14 12:54 0.61756  92.39 15.16
2016 May 22 11:11  241:34 15:58 -21:39 -2.06 2016 May 30 21:36 0.50321  75.28 18.60
2018 Jul 27 05:07  303:53 20:33 -25:30 -2.78 2018 Jul 31 07:51 0.38496  57.59 24.31
2020 Oct 13 23:20   20:12 01:22 +05:26 -2.62 2020 Oct  6 14:19 0.41492  62.07 22.56
2022 Dec  8 05:36   75:47 04:59 +25:00 -1.87 2022 Dec  1 02:18 0.54447  81.45 17.19
2025 Jan 16 02:32  115:52 07:56 +25:07 -1.38 2025 Jan 12 13:38 0.64228  96.08 14.57
2027 Feb 19 15:45  150:23 10:18 +15:23 -1.21 2027 Feb 20 00:14 0.67792 101.42 13.81
2029 Mar 25 07:43  184:32 12:23 +01:04 -1.34 2029 Mar 29 12.56 0.64722  96.82 14.46
2031 May  4 11:57  223:25 14:46 -15:29 -1.80 2031 May 12 03:50 0.55336  82.78 16.91
2033 Jun 27 01:24  275:39 18:30 -27:50 -2.51 2033 Jul  5 11:19 0.42302  63.28 22.13
2035 Sep 15 19:33  352:19 23:43 -08:01 -2.84 2035 Sep 11 14:21 0.38041  56.91 24.61
2037 Nov 19 09:04   56:51 03:37 +20:16 -2.16 2037 Nov 11 08:00 0.49358  73.84 18.96
2040 Jan  2 15:21  101:16 06:50 +26:41 -1.53 2039 Dec 28 14:47 0.61092  91.39 15.32
2042 Feb  6 11:59  137:14 09:25 +19:50 -1.24 2042 Feb  5 07:57 0.67174 100.49 13.93
2044 Mar 11 12:44  170:59 11:33 +06:56 -1.26 2044 Mar 14 06:07 0.66708  99.79 14.03
2046 Apr 17 18:01  207:15 13:44 -09:00 -1.58 2046 Apr 24 04:33 0.59704  89.32 15.68
2048 Jun  3 14:45  253:01 16:45 -24:45 -2.22 2048 Jun 12 01:41 0.47366  70.86 19.76
2050 Aug 14 07:46  321:02 21:43 -20:44 -2.87 2050 Aug 15 12:55 0.37405  55.96 25.02
2052 Oct 28 06:28   34:49 02:12 +11:58 -2.46 2052 Oct 20 05:12 0.44091  65.96 21.23
2054 Dec 17 22:09   85:25 05:40 +26:20 -1.73 2054 Dec 11 11:44 0.57015  85.29 16.42
2057 Jan 24 01:26  123:44 08:28 +23:27 -1.32 2057 Jan 21 09:03 0.65552  98.06 14.28
2059 Feb 27 05:25  157:48 10:44 +12:20 -1.22 2059 Feb 28 10:32 0.67681 101.25 13.83
2061 Apr  2 12:47  192:27 12:50 -02:38 -1.41 2061 Apr  7 13:54 0.63199  94.54 14.81

.. more to come soon ..

Closest Approaches of Mars to Earth

Mars oppositions are closest if the red planet is close to its perihelion when it comes into opposition to the Sun from Earth. Closest approaches can become closer than 56 million km at these times, if the perihelion at its heliocentric eclipitcal length of 336 deg is hit well.

Very close encounters of Mars to Earth happened in Halley's and Newton's time in 1687 and 1719, in Messier's time in 1766, in the time of John Herschel in 1845, and in 1924 when galaxies had just been recognized by Hubble as island universes. The latter two (1845 and 1924) have already been millennia records each, as is the close encounter of 2003.

Following is a list of all close encounters when Mars has approached, or will approach Earth closer than 56.00 million km .. during the first 3 millennia A.D. (1 AD to 3000 AD).

 AD   Oppos. Encount.   km      AU

 756  Jul 28  Jul 27  55.90M      0.37369    !
 835  Aug  2  Aug  1  55.90M      0.37391
1040  Jul 27  Jul 27  55.92M      0.37382
1119  Aug  1  Jul 31  55.859,488  0.37339761 !
1198  Aug  5  Aug  3  55.87M      0.37346
1277  Aug  9  Aug  7  55.96M      0.37409
1482  Aug  3  Aug  3  55,808,594  0.37305741 !
1561  Aug  7  Aug  7  55,837,780  0.37325251
1640  Aug 21  Aug 20  55.87M      0.37347
1687  Aug  8  Aug  9  56.00M      0.37434
1719  Aug 27  Aug 25  55,951,099  0.374010
1766  Aug 13  Aug 13  55,838,948  0.37326031
1845  Aug 18  Aug 18  55,803,163  0.37302110 !
1924  Aug 23  Aug 22  55,776,939  0.37284581 !
2003  Aug 28  Aug 27  55,758,006  0.37271925 !
2050  Aug 14  Aug 15  55.957M     0.374051
2082  Sep  1  Aug 30  55,883,780  0.373564
2129  Aug 19  Aug 19  55,841,268  0.37327582
2208  Aug 24  Aug 24  55,769,117  0.37279352
2287  Aug 29  Aug 28  55,688,405  0.37225400 !
2366  Sep 03  Sep 02  55,708,568  0.37238878
2445  Sep 07  Sep 05  55,794,535  0.37296343
2492  Aug 23  Aug 24  55,832,521  0.37321735
2571  Aug 30  Aug 30  55,707,590  0.37238224
2650  Sep 04  Sep 03  55,651,582  0.37200785 !
2729  Sep 09  Sep 08  55,651,099  0.37200418 !
2808  Sep 13  Sep 11  55,695,623  0.37230224
2855  Aug 30  Aug 31  55,815,632  0.37310445
2887  Sep 18  Sep 16  55,788,120  0.37292055
2934  Sep 04  Sep 05  55,676,249  0.37217270

Oppositions at least as close as the 2003 opposition are printed bold. New record approaches are marked with exclamation marks.

The orbit of planet Mars is subject to small and slow periodic and secular changes caused by various perturbations, in particular the gravitational perturbations by the other planets. One of these effects is that the excentricity varies over the millennia, and thus the perihelion and aphelion distances of Mars are subject to small and slow changes. Currently, the excentricity is minutely growing, so that the perihelion distance of Mars is getting a bit smaller and the aphelion distance a bit larger: In 4000 B.C. it was about 0.088, today (about 2000 A.D.) it is about 0.093, and in 6000 A.D., it can be predicted to be about 0.097. This results in a small decrease of the distance between Earth and Mars in perihelion oppositions (and equally small increases for aphelion oppositions), so that records in close approaches will occur in the upcoming centuries.

[Analogous variations of Earth's orbit make the Earth's excentricity currently decreasing, from 0.019 in 4000 B.C. over today's 0.017 to a mere 0.016 in 6000 A.D.]

Within a period of 1 million years, from 500,000 B.C. to 500,000 A.D., the perturbations mentioned above lead to oscillations of the possible minimal distances at perihelic oppositions, between below 54 million km, and more than 64 million km.

The last approach closer than that of August 27, 2003 occurred on September 24, 57,617 B.C. at 55.718 million km (0.372452 AU) when Mars showed up at an apparent diameter of 25.15".
It was even smaller and reached an absolute minimum in the last 500,000 years on January 22, 78,957 B.C. at 53.667 million km (0.358739 AU). Mars was (or could have been) seen as big as 26.11".
The next grand minimum will occur on May 4, 25,695 A.D. at 53.821 million km (0.359769 AU), with Mars at 26.04".
The absolute minimum in the upcoming 500,000 years (and the overall million years under consideration) will be reached on September 20, 294,851 A.D., when the planet will come as close as 53.637 million km (0.358541 AU) and occur under an angular diameter of 26.13". (Wow!)

References:

Jacques Laskar, 2003. Primer of Mars Oppositions. IMCCE/CNRS, Observatoire de Paris, August 2003. Available online.
Jeffrey D. Beish and Donald C. Parker, 2003. The Great 2003 Perihelic Apparition of Mars. Mars Section of the Association of Lunar and Planetary Observers (A.L.P.O.). [Archival copy]
Jean Meeus, 2003. When was Mars close? (March 2003). [Archival copy; PDF]
Jean Meeus, 1983-1995. Astronomical Tables of the Sun, Moon and Planets. Willmann-Bell, Inc., Richmond, Virginia. Here Part 2: Oppositions of Mars 0-3000; pp. 61-96.
Jeffrey D. Beish, ?-2011/current. General Information for Apparitions of Mars. http://www.alpo-astronomy.org/jbeish/General_Info_Mars.html
William Sheenan, 1996. The Planet Mars: A History of Observation and Discovery. University of Arizona Press, 270 pp. In particular: Appendix 1, Oppositions of Mars, 1901-2035.

Hartmut Frommert [contact]

Definitive Version: May 27, 2008
Last Modification: October 19, 2021