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Mars will come closer to Earth on August 27, 2003, than at any other time in your lifetime, not to stage a closer encounter till the year 2287. Far more amazing, Mars hasn't been this close for some 60,000 or 73,000 years, figures that undoubtedly will be scrutinized by serious students of celestial mechanics.1 To read more about these purported claims, check it out in this Sky & Telescope article.
Since Earth is the third planet from the Sun and Mars the fourth, Earth has the inside track in two planets' journeys around the Sun. Consequently, we pass between the Sun and Mars every 26 months, an event astronomers call "opposition."2 At this juncture, Mars stands opposite the Sun in our sky, rising at sunset, setting at sunrise and shining boldly all night long. What's more, Mars makes its nearest approach to Earth at or near opposition, which this year occurs on August 28.3
Oppositions, however, are not equal. Because of Mars' eccentric (oblong) orbit around the Sun, oppositions can bring Mars anywhere from 35 to 63 million miles of Earth. Oppositions coming in late August are the closest whereas those in late February loom the most distant. For telescope enthusiasts hoping to glance at surface features, be forewarned that a close opposition alone doesn't guarantee optimal viewing. Mars and Earth both have atmospheres that can be turbulent, plus Mars wins a lot of notoriety for its huge dust storms. Time will tell about atmospheric clarity this time around.
Though oppositions come roughly every 26 months, particularly close ones occur in cycles of 15 to 17 years. If, indeed, this is the closest opposition in recorded history, Mars had reached the point of diminishing returns some time ago. According to Sky & Telescope Mars comes within 34,646,418 miles on August 27, 2003. Compare this figure with that of August 23, 1924, when Mars was some 34,658,502 miles away (if I calculated correctly) -- a virtual tie.
Before the first space probe explored Mars in 1965, earth-based observatories took advantage of oppositions to see the red planet at its best. Even so, the enhanced views were oftentimes as misleading as they were revealing. Purcival Lowell is well remembered for misinterpreting linear surface features as canals used by Martians for irrigating crops. Seasonal color variations were once thought to indicate lichen, moss, algae or some other form of plant life. Despite these misadventures, the search for martian life continues, the very real possibility tantalizing scientists to this day.
Mars rises into the southeast sky a couple hours after sunset in early August, and at sunset toward the month's end.
1 celestial mechanics is the study of gravitational influences upon heavenly bodies.
2 the ancients noted that 37 Mars oppositions came to pass every 79 Earth years, giving an average 2.135 year (79/37 = 2.135), or a 780 day (79/37 x 365.25 = 780) interval between oppositions. Moreover, this data told Copernicus that Mars made 42 orbits in 79 years, rendering a Mars orbital period of 687 days (79/42 x 365.25 = 687)
3 on page 63 of the Astronomical Tables of the Sun, Moon and Planets, Jean Meeus says the time interval between a Mars' opposition and its least distance from the Earth can be as much as 8.5 days (1969) or as little as ten minutes (2208).
Kepler and Mars
by Bruce McClure
Mars Timeline of Discovery
Mars by J.B. Calvert