Scientists have discovered a lopsided cloud of moon dust hovering over that shining orb in the night sky.
Each speck of dust hangs above the moon for only a few minutes before showering back onto the lunar surface. But the nimbus of dust constantly replenishes, forming a permanent feature around the moon.
The pattern of dust falling back to its home “in due time … will fill in craters,” says the University of Colorado, Boulder’s Mihaly Horanyi, who led the team that found the dust cloud. “Eventually this will erase the footprints of the astronauts.”
The moon wears this hazy veil thanks to the comet dust that speckles the solar system. When a bit of dust from a comet’s tail slams into the moon, the collision kicks up thousands of particles of moon dust, which are carried high above their resting place on the lunar surface, Horanyi says. The moon-dust cloud was especially thick during the Geminid meteor shower, when the Earth and its sidekick swing through a particularly thick belt of debris.
Thick is relative. From near the moon’s surface to more than 70 miles up, the cloud tops out at only 260 pounds of dust. But the rise and fall of all those dust grains helps form the moon’s character, Horanyi says. The team’s findings stem from data collected by NASA’s LADEE spaceship, which reached the moon in 2013. The study appears in this week’s Nature.
Though LADEE managed to find microscopic specks of dust, it did not find the answer to a lunar mystery dating back nearly 50 years. To researchers’ confusion, many Apollo astronauts orbiting the moon reported a strange glow on the lunar horizon. One of the Apollo 17 astronauts even took pen to paper to sketch what he labeled “definite linear streamers” of light out his spacecraft’s window.
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SOURCE: USA Today, Traci Watson