Photo Credit: NASA, ESA, and A. Simon (Goddard Space Flight Center). Acknowledgment: C. Go, H. Hammel (Space Science Institute and AURA), and R. Beebe (New Mexico State University). Science Credit: A. Simon
(Goddard Space Flight Center), G. Orton (Jet Propulsion Laboratory), J.
Rogers (University of Cambridge, UK), and M. Wong and I. de Pater
(University of California, Berkeley)
Jupiter's monster storm, the Great Red Spot, was once so large that
three Earths would fit inside it. But new measurements by NASA's Hubble
Space Telescope reveal that the largest storm in our solar system has downsized significantly.
Jupiter's trademark Great Red Spot — a swirling anticyclonic storm
feature larger than Earth — has shrunken to the smallest size ever
measured. Astronomers have followed this downsizing since the 1930s.
"Recent Hubble Space Telescope observations confirm that the Great
Red Spot (GRS) is now approximately 10,250 miles across, the smallest
diameter we've ever measured," said Amy Simon of NASA's Goddard Space
Flight Center in Greenbelt, Md. Historic observations as far back as the
late 1800s gauged the GRS to be as big as 25,500 miles on its long
axis. The NASA Voyager 1 and Voyager 2 flybys of Jupiter in 1979
measured the GRS to be 14,500 miles across.
Starting in 2012, amateur observations revealed a noticeable increase
in the spot's shrinkage rate. The GRS's "waistline" is getting smaller
by 580 miles per year. The shape of the GRS has changed from an oval to a
circle. The cause behind the shrinking has yet to be explained.
"In our new observations it is apparent that very small eddies are
feeding into the storm," said Simon. "We hypothesized that these may be
responsible for the accelerated change by altering the internal dynamics
and energy of the Great Red Spot."
Simon's team plans to study the motions of the small eddies and also
the internal dynamics of the GRS to determine if these eddies can feed
or sap momentum entering the upwelling vortex.
In the comparison images one Hubble photo was taken in 1995 when the
long axis of the GRS was estimated to be 13,020 miles across. In a 2009
photo, the GRS was measured at 11,130 miles across.
The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency. NASA's Goddard Space Flight
Center in Greenbelt, Md., manages the telescope. The Space Telescope
Science Institute (STScI) in Baltimore conducts Hubble science
operations. STScI is operated for NASA by the Association of
Universities for Research in Astronomy, Inc., in Washington, DC.
For additional information, contact:
Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
Amy Simon
Goddard Space Flight Center, Greenbelt, Maryland
301-286-6738
amy.simon@nasa.gov
