Sunday, July 13, 2014

Mars


Order from Sun: 4
Named For: Roman god of war
Diameter: 4212 miles
Volume: .151 Earth
Gravity: 0.38 Earth
Distance from Sun: 142 million miles
Orbital Period: 686 Earth days
Orbital Inclination: 1.85 degrees
Orbital Eccentricity: .093
Length of Day: 24.62 hours
Temperature: -125F to 25F
Composition: Rock, silicates
Atmospheric Pressure: .06% Earth
Atmospheric Composition: carbon dioxide, nitrogen, sulfuric acid
Moons: 2
Rings: none
Notable Exploration: Mariner 4 (1964), Vikings (1975-6), Pathfinder/Sojourner (1997), Twin Mars Rovers (2004-present), Mars Reconnaissance Orbiter (2006-present), Mars Science Laboratory (2012-present)


Of all the planets, Mars is often considered the most fun to visually observe. Because it is a superior planet, Mars retrogrades. But the real bonus with Mars comes about because of its highly elliptical orbit. While all planets change in brightness, most do only slightly. Mars is the notable exception. At its dimmest, Mars shines just shy of +2 magnitude. At its brightest, an obviously red Mars nearly reaches magnitude -3.

Because of the highly elliptical orbit, the distance from Mars to Earth van vary greatly. The changes in distance bring about the dramatic changes in brightness. Mars is also notable because detail of the planet, its red color, can be observed without a telescope. Of all the planets, Mars is the probably the most fun planet to observe today while it was probably the biggest anomaly for ancient astronomers to explain. By observing Mars over the course of its 2-year bit and various changes, it's no wonder that the ancients thought that it was alive.
In binoculars, Mars does not appear any different than it does to the naked eye, just a bigger, and more red.

In telescopes, though, Mars can be a real treat. By using a medium-sized (4” and up) scope at around 200x power or greater, surface detail of Mars can become apparent, especially when Mars makes a close approach to Earth. The first things to look for on Mars are its polar ice caps, not unlike those of Earth, which can actually build and recede according to the Martian seasons. If you have a really big scope and really steady skies, more can be seen on the Martian surface, namely Mariner Valley, a canyon that would stretch from New York to Los Angeles if transported to Earth. Under the best conditions, one can observe differing colors on the Martian surface, which can, from time to time, be obscured my massive sand storms, whose existence is evidenced by temporary changes to the Martian surface coloring. In years past, it was thought that such changes in surface color were caused by the blooming and dying of of vegetation, much like that of deciduous trees here on Earth


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