http://science.nasa.gov/headlines/y2...n_redperil.htm

Huge Storms Converge
NASA Science News
June 5, 2006

June 5, 2006: The two biggest storms in the solar system are about to
go
bump in the night, in plain view of backyard telescopes.

Storm #1 is the Great Red Spot, twice as wide as Earth itself, with
winds blowing 350 mph. The behemoth has been spinning around Jupiter
for
hundreds of years.

Storm #2 is Oval BA, also known as "Red Jr.," a youngster of a storm
only six years old. Compared to the Great Red Spot, Red Jr. is
half-sized, able to swallow Earth merely once, but it blows just as
hard
as its older cousin.

The two are converging. Closest approach: the 4th of July, according to
Amy Simon-Miller of the Goddard Space Flight Center who has been
monitoring the storms using the Hubble Space Telescope.

"There won't be a head-on collision," she says. "The Great Red Spot is
not going to 'eat' Oval BA or anything like that." But the storms'
outer
bands will pass quite close to one another - and no one knows exactly
what
will happen.

Amateur astronomers are already monitoring the event. Christopher Go of
the Philippines took the picture above using his 11-inch telescope on
May 28th. "The distance between the storms is shrinking visibly every
night," he says.

Similar encounters have happened before, notes JPL's Glenn Or ton, a
colleague of Simon-Miller. "Oval BA and the Great Red Spot pass each
other approximately every two years." Previous encounters in 2002 and
2004 were anti-climatic. Aside from some "roughing" around the edges,
both storms survived apparently unaltered.

This time might be different. Simon-Miller and Orton think Red Jr.
could
lose its red color, ironically, by passing too close to the Great Red
Spot.

Red Jr./Oval BA wasn't always red. For five years, 2000 to 2005, the
storm was pure white like many other small "white ovals" circling the
planet. In 2006 astronomers noticed a change: a red vortex formed
inside
the storm, the same color as the powerful Great Red Spot. This was a
sign, researchers believed, that Oval BA was intensifying.

The color of the Great Red Spot itself is a mystery. A popular theory
holds that the storm dredges up material from deep inside Jupiter's
atmosphere, lifting it above the highest clouds where solar ultraviolet
rays turn "chromophores" (color-changing compounds) red. A beefed-up
Oval BA could suddenly do the same.

Bumping up against the Great Red Spot, however, could weaken Oval BA,
turning it white again. Simon-Miller explains: "We believe the Great
Red
Spot will push Oval BA toward a southern jet stream, which is blowing
against the oval's counterclockwise rotation." This would slow Oval
BA's
spin, possibly reversing the process that reddened it in the first
place.

What will actually happen? "We'll see," she says. That's what
telescopes
are for.

Note to sky watchers: Jupiter is easy to find. It pops out of the
evening twilight before any other star, surprisingly bright. Look for
it
halfway up the southeastern sky at sunset: sky map
<http://science.nasa.gov/headlines/y2006/images/redperil/skymap_north.gif>.