The Planet Mars:
A History of Observation and Discovery

William Sheehan

Appendix 1: Oppositions of Mars, 1901--2035

The table below gives the opposition date, the planet's position in the sky in terms of its right ascension (RA; hour angle from the first point of Aries) and its declination north or south of the equator (the latter is particularly important because, for northern observatories, a far southerly declination interferes with observation of the planet, which must then be viewed through a longer path of the Earth's atmosphere); the apparent size of the disk in seconds of arc; and the distance of the planet in astronomical units (1 a.u. = Earth-Sun distance). Owing to the slight inclination of Mars's orbit to that of the Earth, the minimum separation between the two bodies can actually occur a few days before or after the opposition date.

Opposition date	RA	Declination	Disk (seconds of arc)	Distance (a.u.)
1901 Feb 22	10h 26m	+14° 32'	13.8"	0.678
1903 Mar 29	12h 32m	-00° 05'	14.8"	0.640
1905 May 8	15h 00m	-16° 57'	17.3"	0.543
1907 July 6	19h 01m	-27° 59'	22.7"	0.411
1909 Sept 24	00h 10m	-04° 13'	23.8"	0.392
1911 Nov 25	03h 58m	+21° 43'	18.0"	0.517
1914 Jan 5	07h 05m	+26° 33'	15.1"	0.625
1916 Feb 10	09h 36m	+19° 08'	14.0"	0.675
1918 Mar 15	11h 44m	+05° 55'	14.0"	0.662
1920 Apr 21	13h 57m	-10° 21'	15.8"	0.588
1922 June 10	17h 11m	-25° 55'	20.1"	0.462
1924 Aug 23	22h 19m	-17° 40'	25.1"	0.373
1926 Nov 4	02h 36m	+14° 26'	20.2"	0.465
1928 Dec 21	05h 58m	+26° 39'	15.8"	0.589
1931 Jan 27	08h 42m	+22° 54'	14.0"	0.663
1933 Mar 1	10h 59m	+11° 26'	14.0"	0.675
1935 Apr 6	13h 03m	-03° 52'	15.1"	0.624
1937 May 19	15h 43m	-20° 39'	18.0"	0.515
1939 July 23	20h 13m	-26° 24'	24.1"	0.389
1941 Oct 10	01h 07m	+03° 29'	22.7"	0.414
1943 Dec 5	04h 44m	+24° 24'	17.3"	0.545
1946 Jan 14	07h 44m	+25° 35'	14.8"	0.641
1948 Feb 17	10h 07m	+16° 25'	13.8"	0.678
1950 Mar 23	12h 13m	+02° 20'	14.4"	0.651
1952 May 1	14h 34m	-14° 17'	16.6"	0.564
1954 June 24	18h 12m	-27° 41'	21.6"	0.433
1956 Sept 10	23h 26m	-10° 07'	24.8"	0.379
1958 Nov 16	03h 25m	+19° 08'	19.1"	0.494
1960 Dec 30	06h 39m	+26° 49'	15.5"	0.610
1963 Feb 4	09h 15m	+20° 42'	14.0"	0.671
1965 Mar 9	11h 25m	+08° 08'	14.0"	0.669
1967 Apr 15	13h 35m	-07° 43'	15.5"	0.605
1969 May 31	16h 32m	-23° 56'	19.4"	0.486
1971 Aug 10	21h 27m	-22° 15'	24.8"	0.376
1973 Oct 25	02h 00m	+10° 17'	21.2"	0.441
1975 Dec 15	05h 29m	+26° 02'	16.2"	0.570
1978 Jan 21	08h 20m	+24° 06'	14.4"	0.654
1980 Feb 25	10h 37m	+13° 27'	13.8"	0.677
1982 Mar 31	12h 43m	-01° 21'	14.8"	0.637
1984 May 11	15h 13m	-18° 05'	17.3"	0.537
1986 Jul 10	19h 20m	-27° 44'	23.0"	0.406
1988 Sep 28	00h 27m	-02° 06'	23.8"	0.396
1990 Nov 27	04h 13m	+22° 28'	18.0"	0.523
1993 Jan 7	07h 19m	+26° 16'	14.8"	0.628
1995 Feb 12	09h 47m	+18° 11'	13.8"	0.676
1997 Mar 17	11h 54m	+04° 41'	14.0"	0.661
1999 Apr 24	14h 09m	-11° 37'	16.2"	0.583
2001 Jun 13	17h 28m	-26° 30'	20.5"	0.456
2003 Aug 28	22h 38m	-15° 48'	25.1"	0.373
2005 Nov 7	02h 51m	+15° 53'	19.8"	0.470
2007 Dec 28	06h 12m	+26° 46'	15.5"	0.600
2010 Jan 29	08h 54m	+22° 09'	14.0"	0.664
2012 Mar 3	11h 52m	+10° 17'	14.0"	0.674
2014 Apr 8	13h 14m	-05° 08'	15.1"	0.621
2016 May 22	15h 58m	-21° 39'	18.4"	0.509
2018 Jul 27	20h 33m	-25° 30'	24.1"	0.386
2020 Oct 13	01h 22m	+05° 26'	22.3"	0.419
2022 Dec 8	04h 59m	+25° 00'	16.9"	0.550
2025 Jan 16	07h 56m	+25° 07'	14.4"	0.643
2027 Feb 19	10h 18m	+15° 23'	13.8"	0.678
2029 Mar 25	12h 23m	+01° 04'	14.4"	0.649
2031 May 4	14h 46m	-15° 29'	16.9"	0.559
2033 Jun 27	18h 30m	-27° 50'	22.0"	0.427
2035 Sept 15	23h 43m	-08° 01'	24.5"	0.382

Appendix 2: Perihelic Oppositions of Mars, 1608--2035

Opposition date	Distance (a.u.)
Aug. 3, 1608	0.376
Sept. 22, 1625	0.397
Aug. 21, 1640	0.373
July 21, 1655	0.385
Sept. 8, 1672	0.382
Aug. 8, 1687	0.374
Sept. 26, 1704	0.400
Aug. 27, 1719	0.374
July 26, 1734	0.382
Sept. 14, 1751	0.385
Aug. 13, 1766	0.373
July 12, 1781	0.397
Aug. 30, 1798	0.375
July 31, 1813	0.380
Sept. 19, 1830	0.388
Aug. 18, 1845	0.373
July 17, 1860	0.393
Sept. 5, 1877	0.377
Aug. 4, 1892	0.378
Sept. 24, 1909	0.392
Aug. 23, 1924	0.373
July 23, 1939	0.390
Sept. 10, 1956	0.379
Aug. 10, 1971	0.376
Sept. 28, 1988	0.396
Aug. 28, 2003	0.373
July 27, 2018	0.386
Sept. 15, 2035	0.382

Appendix 3: Table of Data for the Planet Mars

Orbital data
Semimajor axis	227,940,000 km (1.52366 a.u.)
Eccentricity	0.0934
Inclination	1.8504°
Longitude of ascending node	49.59°
Longitude of perihelion	335.94°
Mean orbital velocity	24.13 km/sec
Mean synodic period	779.94 days
Mean sidereal motion	0.5204°/day

Physical elements

Axial inclination 25.19°

Length of sidereal day 24 hr, 37 min, 22.66 sec

Mean orbital period 686.98 Earth days

669.60 Martian solar days

Diameter 6,779.84 kilometers

Polar compression 0.006

Surface area (Earth = 1) 0.2825

Volume (Earth = 1) 0.1504

Mass (Earth = 1) 0.1074

Density (water = 1) 3.93

Mean escape velocity 5.027 km/sec

Physical elements
Axial inclination	25.19°
Length of sidereal day	24 hr, 37 min, 22.66 sec
Mean orbital period	686.98 Earth days
	669.60 Martian solar days
Diameter	6,779.84 kilometers
Polar compression	0.006
Surface area (Earth = 1)	0.2825
Volume (Earth = 1)	0.1504
Mass (Earth = 1)	0.1074
Density (water = 1)	3.93
Mean escape velocity	5.027 km/sec

Source: H. H. Kieffer, B. M. Jakosky, C. W. Snyder, and M. S. Matthews, eds., Mars (Tucson: University of Arizona Press, 1993).

Appendix 4: The Satellites of Mars

	Phobos	Deimos
Mean distance from Mars	9,378 km	23,459 km
Sidereal period	7 hr, 39 min, 13.84 sec	30 hr, 17 min, 54.87 sec
Eccentricity	0.0152	0.0002
Inclination	1.03°	1.83°
Diameter	13.3 x 11.1 x 9.3 km	7.6 x 6.2 x 5.4 km