On September 29, a crazily-rotating, dumbbell-shaped asteroid the size of a small city will pass closer to Earth than any other asteroid this century?but it won't hit us. When astronomers say asteroid Toutatis will come "close," they mean it will be a million miles away from us.
The asteroids astronomers worry about are the ones that pass between us and the moon?now THAT'S close! But a million miles away is around 4 times the distance between Earth and the moon. In space.com, Robert Roy Britt writes: "Asteroid Toutatis, officially numbered 4179, was discovered by French astronomers in 1989. Researchers can't predict far enough into the future to rule out Toutatis ever slamming into Earth, so it is listed officially as a Potentially Hazardous Asteroid. NASA says it won't hit for at least the next six centuries."
We're worried about meteor impacts, but most of us never stop to think about where these meteors come from. It's now been discovered that a meteor that fell on a Soviet military base in Yemen in 1980 came from one of the moons of Mars. This is the only sample of Martian Moon rock that we have.
Jenny Hogan writes in New Scientist that geologist Andrei Ivanov spent two years trying to figure out where the meteor came from. Finally he decided it must be a chip off Phobos, the largest of the two Martian moons. He says, "I can't find a better candidate."
Of the 23,000 meteorites have been catalogued so far, none of them is like the Kaidun meteorite, which contains minerals that have never been seen before. Ivanov calls it "new and weird."
It contains fragments of volcanic rock, which only forms in large, planet-like bodies with a core, mantle and crust. This could come from Martian volcanoes throwing rocks out into the atmosphere. The rest of the meteorite is the same kind of carbon-rich material that only occurs in asteroids. Both Phobos and Mars' other moon Deimos are probably asteroids that were captured by Mars as they passed by the planet, which would explain why the meteorite has so much carbon. The only explanation for all this is if it came from a Martian moon.
Meteorite expert Sara Russell says, "There have been no landers sent to Phobos and so almost nothing is known about the composition and geology of this body." But the European Space Agency is planning to go there soon.
There are many strange mysteries right here on Earth, like why a certain CD can free your imagination in totally new ways and greatly enrich your dream life.
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