Mars

Image Courtesy of NASA/STScl

Observing Mars

To the unaided eye mars has an orange reddish color unlike any of the other planets and can often be confused with red stars in the sky. Viewing it from night to night will reveal that it moves quite quickly across the night sky. Looking through binoculars one can make out the shape of Mars as well as observe its red color. Also as the Earth and Mars make their way around the Sun over the months, its apparent change in size is much more noticeable as it gets either further or closer to us, than is visible from any of the other planets.

When viewed through a small telescope the surface features of Mars become visible. Two bright spots on either of the poles can be seen; these are the two ice caps of Mars which grow and shrink with the seasons of Mars. Mars has two visible moons, Phobos and Deimos, but they are faint and hard to see over Mars’s brightness. Under ideal circumstances (when Mars is at opposition and the moons appear far away from the planet) Phobos and Deimos can be seen through a medium sized telescope.

Locating Mars

Mars is the inner most and closest superior planet, or planet that is further away from the Sun than Earth. Therefore it moves much faster than any of the superior planets, however unlike Venus or Mercury, because it is a superior planet it crosses the entire night sky. The best time to view Mars is at opposition, which is extra special in the case of Mars for a few reasons. One, because Mars is so close to Earth, when it is at opposition it makes a huge difference in observability and can be seen much better than at other times. In fact at this time it appears brighter than Jupiter, which usually outshines it, to become the fourth brightest object in the sky. The second is that because Mars moves so quickly compared to the other outer planets, it takes a very long time for the Earth to catch up to it and over take it, making an opposition with Mars the rarest of the planetary oppositions, occurring only every 26 months. Mars has a highly elliptical orbit which makes some oppositions more profound than others. If you notice that a Mars opposition date is coming soon on the Astronomical Calendar, make sure to take advantage of it.

Facts About Mars

Average Distance from the Sun: 1.52 AU (279,000,000 km)
Orbital Period: 1.88 years (687 days)
Length of Day: 24.6 hours
Mass: 6.42×1023 kg (0.107 Earth masses)
Diameter (equatorial): 142,800 km (0.532 times the Earth)
Surface Temperature Range: 20°C to -140°C / 68°F to -220°F

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