Just ahead of a historically close approach to Earth later in August, Mars has become the “star” of the night.
FOR MONTHS VISIBLE only during morning hours, the Red Planet began August rising around 9:45 or 10 p.m. local daylight time and peeks above the horizon about four minutes earlier each night. Mars is now the third-brightest object in the nighttime sky, after the moon and Venus. To the unaided eye, Mars is by far the brightest “star” in the late-evening sky. Venus is currently too near the sun to be visible.
Astronomers measure brightness of stars and planets on a scale in which smaller numbers represent brighter objects. Already dazzling, Mars attains unusual brilliance this month, reaching magnitude -2.9 on Aug. 22 and staying that bright through Sept. 3. Venus can reach magnitude -4.0 or brighter.
Anyone who has a telescope, no matter how modest it is, will probably want to find out what it can do with Mars. So what’s to be seen?
As the month progresses, the south polar cap — visible now to moderate-sized backyard telescopes — will be melting and shrinking down to a tiny white speck. The largest dark markings on the planet should be fairly easy to see in almost any telescope at 100-power and up, but finer details are notoriously difficult to spot.
Serious observers are keeping their fingers crossed that a major dust storm does not develop as Mars’ closest approach to the Earth draws nearer. The last time Mars passed relatively close to Earth (though not this close), in June 2001, a planetwide dust storm veiled most surface features for months.
Earth and Mars are nearer than normal because they’re lining up on the same side of the sun. A case of orbital fate, due to the fact that the planet’s orbits are not quite circular, has made special what would otherwise be a normal “opposition” event: Earth will be almost as far as it ever gets from the sun, and Mars will be about as close to the sun as it can be.
Mars comes closest to the Earth on the morning of Aug. 27 at 5:51 a.m. ET. The planet is then 34,646,418 miles (55,758,006 kilometers) from Earth, measured from center to center. This is closer to Earth than Mars has been in nearly 60,000 years, and Mars won’t come as close again until the year 2287.
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.
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