Mars - Viewing

Viewing

Because the orbit of Mars is eccentric, its apparent magnitude at opposition from the Sun can range from −3.0 to −1.4. The minimum brightness is magnitude +1.6 when the planet is in conjunction with the Sun. Mars usually appears a distinct yellow, orange, or reddish color; the actual color of Mars is closer to butterscotch, and the redness seen is just dust in the planet's atmosphere; considering this, NASA's Spirit rover has taken pictures of a greenish-brown, mud-colored landscape with blue-grey rocks and patches of light red colored sand. When farthest away from the Earth, it is more than seven times as far from the latter as when it is closest. When least favorably positioned, it can be lost in the Sun's glare for months at a time. At its most favorable times—at 15- or 17-year intervals, and always between late July and late September—Mars shows a wealth of surface detail to a telescope. Especially noticeable, even at low magnification, are the polar ice caps.

As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to move backwards in a looping motion with respect to the background stars. The duration of this retrograde motion lasts for about 72 days, and Mars reaches its peak luminosity in the middle of this motion.