http://science.nasa.gov/headlines/y2006/02mar_redjr.htm

Jupiter's New Red Spot
NASA Science News
March 3, 2006

March 3, 2006: Backyard astronomers, grab your telescopes. Jupiter is
growing a new red spot.

Christopher Go of the Philippines photographed it on February 27th
using
an 11-inch telescope and a CCD camera:

The official name of this storm is "Oval BA," but "Red Jr." might be
better. It's about half the size of the famous Great Red Spot and
almost
exactly the same color.

Oval BA first appeared in the year 2000 when three smaller spots
collided and merged. Using Hubble and other telescopes, astronomers
watched with great interest. A similar merger centuries ago may have
created the original Great Red Spot, a storm twice as wide as our
planet
and at least 300 years old.

At first, Oval BA remained white - the same color as the storms that
combined to create it. But in recent months, things began to change:

"The oval was white in November 2005, it slowly turned brown in
December
2005, and red a few weeks ago," reports Go. "Now it is the same color
as
the Great Red Spot!"

"Wow!" says Dr. Glenn Orton, an astronomer at JPL who specializes in
studies of storms on Jupiter and other giant planets. "This is
convincing. We've been monitoring Jupiter for years to see if Oval BA
would turn red - and it finally seems to be happening." (Red Jr? Orton
prefers "the not-so-Great Red Spot.")

Why red?

Curiously, no one knows precisely why the Great Red Spot itself is red.
A favorite idea is that the storm dredges material from deep beneath
Jupiter's cloudtops and lifts it to high altitudes where solar
ultraviolet radiation--via some unknown chemical reaction - produces
the
familiar brick color.

"The Great Red Spot is the most powerful storm on Jupiter, indeed, in
the whole solar system," says Orton. The top of the storm rises 8 km
above surrounding clouds. "It takes a powerful storm to lift material
so
high," he adds.

Oval BA may have strengthened enough to do the same. Like the Great Red
Spot, Red Jr. may be lifting material above the clouds where solar
ultraviolet rays turn "chromophores" (color-changing compounds) red. If
so, the deepening red is a sign that the storm is intensifying.

"Some of Jupiter's white ovals have appeared slightly reddish before,
for example in late 1999, but not often and not for long," says Dr.
John
Rogers, author of the book "Jupiter: The Giant Planet," which recounts
telescopic observations of Jupiter for the last 100+ years. "It will
indeed be interesting to see if Oval BA becomes permanently red."

See for yourself: Jupiter is easy to find in the dawn sky. Step outside
before sunrise, look south and up: sky map
images/redjr/skymap_north.gif. Jupiter outshines everything around
it.
Small telescopes have no trouble making out Jupiter's cloudbelts and
its
four largest moons. Telescopes 10-inches or larger with CCD cameras
should be able to track Red Jr. with ease.

What's next? Will Red Jr. remain red? Will it grow or subside? Stay
tuned for updates.