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Moon patterns
finally explained
By Meghan Rosen
Scientists have charged up an old moon
mystery. New research suggests that
swirling designs on the dusty lunar surface might be the product of electric
fields generated by magnetic bubbles.
“People have been looking at these
strange, mysterious structures since
the invention of the telescope,”
says physicist Ruth Bamford of the
Rutherford Appleton Laboratory in
Didcot, England. “Now we know exactly
how they are made.”
The milky patterns stand out like pale
flesh against darkly tanned skin. It’s as
if you used sunblock to paint whorls on
your arm and then spent the day out-
side, says planetary geologist Georgiana
Kramer of the Lunar and Planetary Insti-
tute in Houston. The sun would color
everything but the protected skin, leav-
ing the whorls a lighter shade.
Scientists have long suspected that
weak magnetic fields near the moon’s
surface might shape the looping patterns.
The moon doesn’t have a dynamo-driven
magnetic field like Earth’s, but researchers have found patchy magnetic bubbles
scattered throughout the lunar crust.
Data from the Apollo missions fed a
theory that the moon’s magnetic bubbles
act like a solar wind sunblock. The solar
wind — a steady stream of charged particles from the sun — constantly buffets
the moon, turning pale lunar dust dark.
But magnetic bubbles might protect the
moon’s crust, keeping silvery soil fresh
and young-looking.
The mystery, Bamford says, was how
such puny fields could deflect the raging solar wind. The answer is the bubbles’ electric field, Bamford and her
colleagues suggest in an upcoming
Bright designs called lunar swirls dot
the moon’s surface. This one spans
about 60 kilometers of the nearside.
Physical Review Letters.
Usually, the solar wind’s charged
particles travel together. But when the
wind smacks into the moon’s magnetic
bubbles, flimsy negatively charged par-
ticles skirt around the bubble and hefty
positive ones try to penetrate it. Splitting
apart these oppositely charged particles
whips up a heavy-duty electric field.
Hubble spots a fifth Pluto moon
Dwarf planet’s celestial retinue continues to expand
By Nadia Drake
Pluto, the popular dwarf formerly known
as a planet, has another little friend:
a fifth moon, first reported early the
morning of July 11 on Twitter.
“Just announced: Pluto has some
company — We’ve discovered a 5th moon
using the Hubble Space Telescope!”
tweeted Alan Stern of the Southwest
Research Institute in Boulder, Colo.
On July 7, Mark Showalter of the SETI
Institute in Mountain View, Calif., spotted the fifth moon, referred to as P5 for
now, in images captured by Hubble.
P5 revealed itself in 14 sets of images,
each containing around a dozen three-
minute exposures. Hubble has been
peering at the Pluto system since June,
tasked with helping astronomers detect
any potential hazards to NASA’s New
Horizons spacecraft as it flies by the
dwarf planet in 2015. The team is hoping
to have enough time to plan an alternate
route through the system if the probe’s
current trajectory points toward trouble.
