Celestial News: Earth meets Mars this month
July 5, 2018
Earth and Mars are about to have a close encounter of the planetary kind later this month. When at its closest, Mars will shine almost two times brighter as the dazzling planet Jupiter and, with its rusty-red color, it will be a spectacular beacon in our midsummer sky.
It takes an average of 780 days for the faster-moving Earth to gain a lap on Mars and pass between it and the sun for an opposition, so, close approaches to Mars only happen about once every two years. But, because of Mars' lopsided orbit, some oppositions are closer and more favorable than others.
This year's opposition on the night of July 26 is the best and closest we've had since 2003. Under the most favorable conditions, Mars can come as close as 34.6 million miles to Earth, as it did in 2003. When Mars reaches opposition on July 26, it will be 35.9 million miles from Earth. Closest approach to Mars will happen five days later on July 31 when Mars will be 35.8 million miles from Earth.
Through a medium-sized backyard telescope, Mars will look like a flaming red ball, but look more closely and you might be able to make out some of its dark-colored deserts and maybe even its snowy white south polar ice cap. Glimpsing these Martian features through your own backyard telescope is a thrill that doesn't present itself but once every 15 years, so make the most of it.
Mars will be glowing prominently in the southern constellation of Capricornus, the Sea Goat, during opposition this year. In late July, watch for it rising in the southeastern sky around 10 p.m., and shining high in the southern sky around midnight. On the night of opposition, the full Green Corn Moon will rise just ahead of Mars and lead it across the sky all night, from dusk to dawn. The moon also will pair up with the Red Planet about once a month for the rest of the year on these nights: Aug. 22, Sept. 19, Oct. 17, Nov. 15, and Dec. 14.
As a cosmic bonus, the ringed planet Saturn will be shining about two hand spans to the west of Mars and Jupiter will be about three hand spans west of Saturn.
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One month after opposition, on Aug. 26, watch as Mars poses beside a tiny crucifix-shaped star pattern called the Terrebellum. Binoculars will offer the best view of Mars meeting the twinkly stars of the Terebellum.
Jimmy Westlake retired from full-time teaching at Colorado Mountain College's Steamboat campus in 2017, after 19 years as professor of physical sciences. His “Celestial News” column appears monthly in Steamboat Pilot & Today. Check out Westlake's astrophotography website at jwestlake.com.