Jupiter`s Trademark Red Spot Is Shrinking

National Aeronautics and Space Administration
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Jupiter’s Trademark Red Spot Is Shrinking
By NASA’s Amazing Space reporters
May 2014
I
magine a storm SO LARGE
that Earth would fit inside it.
That Earth-sized storm is on
Jupiter, the largest planet in the
solar system. Called the Great Red
Spot, the storm has been raging
in Jupiter’s cloudy atmosphere
for at least a hundred years.
Astronomers using the Hubble Space
Telescope have discovered that the
well-known storm has shrunk to
10,250 miles across, the smallest size
ever measured. Observations during
the late 1800s, however, showed
that the storm was so enormous —
25,500 miles across — that three
Earths could squeeze inside it.
Astronomers have been following
its downsizing since the 1930s.
Starting in 2012, however, amateur
astronomers noticed an increase in
the spot’s shrinkage rate. The red
spot is getting smaller by 550 miles
Continued, page 2…
IMAGE: NASA, ESA, and A. Simon (GSFC)
Jupiter’s Great Red Spot, April 21, 2014:
Astronomers using the Hubble Space Telescope have discovered that Jupiter’s
legendary Great Red Spot is the smallest ever seen. See the changes in the red
spot from 1995 to 2014, on page 2.
Continued from page 1…
a year. Even its shape has changed
from an oval to a circle.
Astronomers do not know why
the storm’s size is decreasing. One
possibility is that some unknown
activity deep inside the planet’s
atmosphere may be draining energy
and weakening the storm, causing it
to shrink.
A swirling storm of rising air
The Great Red Spot shares some
characteristics with hurricanes
on Earth, including a circular
motion and strong winds. Unlike
a hurricane, the red spot rotates
counterclockwise. The red spot also
is a high-pressure system, where air
rises. Hurricanes, on the other hand,
are low-pressure systems, where air
sinks. One reason the Jupiter storm
may have lasted so long is that there
is no solid surface to decrease the
storm’s energy and slow it down.
Hurricanes, however, lose strength
when they reach land.
The swirling storm towers six miles
above Jupiter’s multicolor cloud tops.
Inside the red spot, some winds
reach speeds of up to 400 miles an
hour. The exact cause of the storm’s
signature red color is a mystery. One
theory is that the material being
pulled upward from deep inside
Jupiter’s atmosphere turns red when
sunlight strikes it. The spot, however,
is not always bright red. Sometimes
its color is much lighter, and, rarely,
can even be very pale.
The first record of the Great Red
Spot was a drawing made in 1831
by German amateur astronomer
Samuel Heinrich Schwabe. The
storm, however, may have been seen
Continued, page 4…
2
Jupiter’s
shrinking
red spot
Hubble close-ups,
1995 to 2014
Astronomers using the
Hubble Space Telescope
have discovered that
Jupiter’s legendary
Great Red Spot is the
smallest ever seen.
1995
The three close-up Hubble
views at right show that
the red spot’s size has
decreased significantly
between 1995 and 2014.
In the 1995 image, the red
spot was about 13,020
miles across. In the 2009
image, the trademark feature
measured 11,130 miles
across. The 2014 image
reveals that the spot is only
10,250 miles wide.
2009
2014
IMAGES:
1995: NASA, ESA, and R. Beebe (New Mexico State Univ.);
2009: NASA, ESA, and H. Hammel (Space Science Institute and AURA);
2014: NASA, ESA, and A. Simon (GSFC)
Hubble’s
April 2014
view of
Jupiter
The Hubble image at
left is a view of the
entire planet. The
red spot, a monster
storm in Jupiter’s
atmosphere, is at
lower right.
IMAGE: NASA/JPL
IMAGE: NASA, ESA, and A. Simon (GSFC)
1979: The red spot, as viewed by Voyager 2
This image, taken by
NASA’s Voyager 2
spacecraft, shows the
region around Jupiter’s
Great Red Spot, a giant
storm that has been raging
for at least a hundred years.
A white oval-shaped storm
can be seen just below the
red spot. The image was
taken July 3, 1979, when
the spacecraft was almost
4 million miles (6 million
kilometers) from Jupiter.
Movie of the red
spot, Voyager 1
Also in 1979, NASA’s
Voyager 1 imaged Jupiter
every time the red spot
passed under the spacecraft.
The resulting movie is clear
evidence of the dynamic
nature of the Jovian
atmosphere. To see the
movie, go to:
http://amazing-space.stsci.edu/
news/archive/2014/02/extra-01.php
IMAGE: NASA/JPL
3
Continued from page 2…
200 years earlier, in 1665, by Italian
astronomer Gian Domenico Cassini,
who noted a monster storm he called
the “Permanent Spot.”
1677: Cassini’s drawing of Jupiter
The red spot has been continuously
observed since 1878. NASA’s
Voyager spacecraft also made the
first detailed observations of the
feature in 1979, and even took a
movie of its six-day rotation.
IMAGE: Courtesy Bibliothèque Nationale de France
This drawing of Jupiter was made in 1677 by Italian
astronomer Gian Domenico Cassini. He called the dark
spot at bottom, center the “Permanent Spot.” It may be
the same storm as the Great Red Spot.
SEE MORE Hubble images and read more
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for K-12 students and teachers.
amazing-space.stsci.edu
www.nasa.gov