When
17th-century astronomers first turned their telescopes to Jupiter, they
noted a conspicuous reddish spot on the giant planet. This Great Red Spot
is still present in Jupiter's atmosphere, more than 300 years later. It
is now known that it is a vast storm, spinning like a cyclone. Unlike a
low-pressure hurricane in the Caribbean Sea, however, the Red Spot rotates
in a counterclockwise direction in the southern hemisphere, showing that
it is a high-pressure system. Winds inside this Jovian storm reach speeds
of about 270 mph.
The Red Spot is the largest known storm in the Solar System. With a diameter
of 15,400 miles, it is almost twice the size of the entire Earth and one-sixth
the diameter of Jupiter itself. |
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The
long lifetime of the Red Spot may be due to the fact that Jupiter is mainly
a gaseous planet. It possibly has liquid layers, but lacks a solid surface,
which would dissipate the storm's energy, much as happens when a hurricane
makes landfall on the Earth. However, the Red Spot does change its shape,
size, and color, sometimes dramatically.
Such changes are demonstrated in high-resolution Wide Field and Planetary
Cameras 1 & 2 images of Jupiter obtained by NASA's Hubble Space Telescope,
and presented here by the Hubble Heritage Project team. The mosaic presents
a series of pictures of the Red Spot obtained by Hubble between 1992 and
1999 (see PIA01594 thru PIA01599 and PIA02400 thru PIA02402 for individual
images). |
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