NUMBER 7
Electrostatic Levitation
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Cheese is just one of the many weird things that come from
the Moon.
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Astronauts
aboard the Apollo missions in the 1960s and 1970s reported a weird glow on the
horizon of the Moon, one that resembled something that might occur in Earth's
atmosphere.
"This was unexpected since apart from a few rogue atoms evaporated
out of the Moon's barren surface, our satellite doesn't have an atmosphere to
speak of," says Matthew Genge of the London Natural History Museum.
Moon clouds? Lunar aurora? The Man on the Moon with a lava
lamp?
"The glow actually came from the reflection of sunlight from dust
particles that lift up from the Moon's surface," Genge says. "It's a
process known as electrostatic levitation."
Sunlight gives an electrostatic charge to dust particles on the Moon, Genge explains, causing some to
lift off the surface. While it might sound like something out of I Dream of
Jeannie, it's real, and it's one of the weirdest things in space.
So weird, in fact, that some of this Moon dust actually ends up on Earth.
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Weird Fact
Evidence of electrostatic levitation has also been found
on asteroids.
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More About Electrostatic Levitation
Genge explains that the particles of Moon dust all develop a positive charge
(around 10 volts). Since the particles all have the same charge, they repel
each other, forcing some upward. Some particles can be lifted so high that they
get swept away by the solar wind, a stream of charged particles that races away
from the Sun.
The result is a tail of dust streaming out behind the Moon. Some of this
dust gets snagged in Earth's magnetosphere, a protective envelope of magnetic
energy that surrounds our planet.
"Long before mankind went to the Moon, small bits of the Moon were
coming to us," Genge says, adding that some of it is collected in the atmosphere
by NASA research projects. "There's something rather fascinating about the
fact that dust may be lifted of the surface of the Moon and delivered to the
surface of our planet by nothing much more than sunlight."
Because the phenomenon is no more than a curiosity, Genge says few
scientists are looking into this weird thing in space.
But recent studies of Jupiter's moon Callisto have shown inexplicable
wanderings of volcanic debris -- again on a moon with no atmosphere to speak
of. NASA scientists have suggested that electrostatic levitation might be the
cause.
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