NASA craft closes in on first-ever Mercury orbit
Source: Agencies |
March 12, 2011, Saturday
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Print Edition
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EARTH is about to get better -acquainted with its oddball planetary cousin, Mercury, a rocky -wonderland of extremes.
Mars may fascinate science fiction authors, Jupiter looms large and Saturn has stunning rings, but tiny Mercury can claim the title as weirdest planet in the solar system.
It has the wildest extremes from hot to cold. A day on Mercury somehow last longer than its year. And maybe strangest of all, scientists think it holds tons of ice in craters despite being the planet closest to the sun.
Next Thursday, for the first time, a small NASA spacecraft called Messenger will enter into Mercury's orbit, circling at times as close as 200 kilometers from the planet's surface. And by coincidence, a few days before that will be the best time all year for people on Earth to see Mercury with the naked eye.
Barely bigger than our moon but much more distant, Mercury is not easy to see without a telescope. An odd pairing with giant Jupiter will make it easier to spot starting tomorrow - probably the best opportunity for a year, said Geoff Chester at the US Naval Observatory in Washington.
Chester said people in the Northern Hemisphere should look to the west after sunset. Jupiter will be about 10 degrees above the western horizon. Mercury will be about finger's width to the right of Jupiter.
"Mercury has sometimes been called the forgotten planet," said Sean Solomon, the Carnegie Institution planetary geologist who is Messenger's chief scientist. "It is extreme in many respects. It is the smallest, closest to the sun. It is made of the densest materials."
One myth about Mercury is that it's the hottest planet in the solar system. Mercury has a tenuous atmosphere with wild swings in temperature. When parts of Mercury face the sun, it can be 800 degrees. On the opposite side, it can be 300 degrees below zero, said mission scientist Ralph McNutt. Near its poles there are craters that "never see any sunlight," McNutt said. Therefore, scientists think the craters have ice.
Mars may fascinate science fiction authors, Jupiter looms large and Saturn has stunning rings, but tiny Mercury can claim the title as weirdest planet in the solar system.
It has the wildest extremes from hot to cold. A day on Mercury somehow last longer than its year. And maybe strangest of all, scientists think it holds tons of ice in craters despite being the planet closest to the sun.
Next Thursday, for the first time, a small NASA spacecraft called Messenger will enter into Mercury's orbit, circling at times as close as 200 kilometers from the planet's surface. And by coincidence, a few days before that will be the best time all year for people on Earth to see Mercury with the naked eye.
Barely bigger than our moon but much more distant, Mercury is not easy to see without a telescope. An odd pairing with giant Jupiter will make it easier to spot starting tomorrow - probably the best opportunity for a year, said Geoff Chester at the US Naval Observatory in Washington.
Chester said people in the Northern Hemisphere should look to the west after sunset. Jupiter will be about 10 degrees above the western horizon. Mercury will be about finger's width to the right of Jupiter.
"Mercury has sometimes been called the forgotten planet," said Sean Solomon, the Carnegie Institution planetary geologist who is Messenger's chief scientist. "It is extreme in many respects. It is the smallest, closest to the sun. It is made of the densest materials."
One myth about Mercury is that it's the hottest planet in the solar system. Mercury has a tenuous atmosphere with wild swings in temperature. When parts of Mercury face the sun, it can be 800 degrees. On the opposite side, it can be 300 degrees below zero, said mission scientist Ralph McNutt. Near its poles there are craters that "never see any sunlight," McNutt said. Therefore, scientists think the craters have ice.
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