Jupiter
growing another red spot
The Great Red Spot that has dominated the planet Jupiter's
cloudtops for hundreds of years now has a companion.
The gas giant is growing another red spot, which US space agency
(Nasa) astronomers have nicknamed "Red Jr".
Both red spots are actually raging storms in Jupiter's cloud layer,
but scientists don't yet know how they get their characteristic
brick colour.
Red Jr is about half the size of the Great Red Spot and almost
exactly the same colour, [email protected] reports.
The new storm goes by the official name of Oval BA. It was first
observed in 2000, when three smaller spots collided and
merged.
Changing colours
At first, Oval BA remained white - the same colour as the storms
that combined to create it. But over the past few months, it has
started to change in appearance.
"The oval was white in November 2005, it slowly turned brown in
December 2005, and red a few weeks ago," said Christopher Go, an
amateur astronomer from the Philippines who has been observing Red
Jr.
Some scientists believe a similar merger to the one that created
Red Jr may have created the Great Red Spot, which is twice as wide
as our planet and at least 300 years old.
Dr Glenn Orton, an astronomer at Nasa's Jet Propulsion Laboratory
who studies storms on Jupiter and other giant planets, said: "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."
No one is quite sure why the Great Red Spot is red.
One theory is that the storm dredges material from deep beneath
Jupiter's cloudtops and lifts it to high altitudes. Here,
ultraviolet rays from the Sun turn colour-changing compounds (or
chromophores) red.
Oval BA may have strengthened enough to do the same, scientists
say.
