2014 APPARITION CHARACTERISTICS (MARS) Another general rule for predicting oppositions of Mars is from the following: the planet has an approximate 15.8-year periodic opposition cycle, which consists of three or four Aphelic oppositions and three consecutive Perihelic oppositions. Perihelic oppositions are also called favorable because the Earth and Mars come closest to each other on those occasions. We sometimes refer to this as the seven Martian synodic periods. This cycle is repeated every 79 years (± 4 to 5 days) and, if one were to live long enough, one would see this cycle nearly replicated in approximately 284 years. The 2014 Mars apparition is considered Aphelic because the orbital longitude at opposition will be only 44° from the aphelion longitude of 70° Ls. NOTE: Ls is the planetocentric longitude of the Sun along the ecliptic of Mars’ sky. 0° Ls is defined as that point where the Sun crosses the Martian celestial equator from south to north, that is the planet’s northern hemisphere vernal equinox. The other Ls values that define the beginnings of Martian northern hemisphere seasons are: summer, 90° Ls; autumn, 180° Ls; and winter, 270° Ls. For Mars’ southern hemisphere these values represent the opposite seasons. Distance (A.U.) - Distance from Earth to Mars in astronomical units, where one (1) A.U. equals 92,955,807.267 miles or 149,597,870.691 km. Opposition occurs nearly 12 months after conjunction when Mars is on the opposite side of the Earth from the Sun. At that time, the two planets will lie nearly in a straight line with respect to the Sun, or five and a half weeks after retrogression begins. Opposition will occur at 2057 UT on April 08, 2014 (113.7° Ls) with an apparent planetary disk diameter of 15.1 arcsec. Mars will remain visible for more than twelve months after opposition and then become lost in the glare of the Sun around April 30, 2015 as it approaches the next conjunction (June 14, 2015). The cycle is complete in 780 Earth days. Closest approach occurs at 1254 UT on April 14, 2014 (116.4° Ls) with an apparent planetary disk diameter of 15.2’’ at a distance of 0.617565503 astronomical units (AU) or 57,406,300 miles (92,386,484 km). During closest approach in 2014 the apparent diameter of Mars will be more than 1.3 arcsec larger than it was at the same period in 2012; however, it will be nearly 15 degrees lower in the sky – not quite as good for observing the Red Planet. [NOTE: one (1) A.U. equals 92,955,807.267 miles or 149,597,870.691 km]. It should also be noted that closest approach between Earth and Mars is not necessarily coincident with the time of opposition but varies by as much as two weeks. alpo-astronomy.org/jbeish/2014_MARS.htm
Posted on: Thu, 10 Apr 2014 06:27:51 +0000
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