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The Great Red Spot of Jupiter
captured by Voyager 1 in 1979.
(Credit: NASA ) |
The Great Red Spot (GRS) is
an anticyclonic atmospheric storm which is present in the southern hemisphere
of Jupiter.
Since it is an anticyclonic, it is a high pressure storm opposite to the
cyclones present on Earth. It is also called the eye of Jupiter.
The GRS is very old storm and first observed and described by Giovanni Cassini
in the 1665. It is believed that it had just formed at that time.
It is the largest
atmospheric storm of our solar system and it can be easily viewed by the telescope. The spot is
so large that it can engulf three Earths easily. 100 years ago, it's
size was about 40000 Km but it is observed that the size of
the GRS is shrinking.
Wind velocity data
collected from 1996 to 2006 has allowed scientists to size up the storm more
accurately by analyzing wind speeds and directions. “The velocity data show
that the Red Spot has been shrinking along its major diameter by about 15 per
cent over that period”, said Xylar Asay-David, who conducted the study along
with Phil Marcus, Mike, Wong and Lmke de Pader at the University of California
at Berkeley. “We find that the Red Spot has been shrinking but not slowing
down”, said Asay-David.
At present rate, this storm
will become circular by 2040. It is not known how long the spot will last, or
whether the changes in size are result of normal fluctuations.
The GRS rotates counter clockwise and completes one full rotation in 6 Earth days. The rotation period of GRS is decreased. Some believe that this is the result of shrinking of the spot. The speed of wind at the edge of storm is very high up to 432 km/hr. but inside the storm the winds do not show any inflow or outflow.
The GRS rotates counter clockwise and completes one full rotation in 6 Earth days. The rotation period of GRS is decreased. Some believe that this is the result of shrinking of the spot. The speed of wind at the edge of storm is very high up to 432 km/hr. but inside the storm the winds do not show any inflow or outflow.
Infrared data suggest that
the altitude of storm is higher than the neighbouring clouds by 8 km. The data
also indicate that the GRS is colder than surrounding. The spot does not move
along south or north directions. The GRS does not come on the surface of Jupiter which
results in the continuous high speed storm. Unlike this, the cyclone on Earth comes on ground and get slow down.
The other interesting
feature of the GRS is its colour. The most popular theory, which is supported
by laboratory experiments claims that the colour of the red spot is caused by
complex organic molecules, red phosphorus, or other sulphur compounds. The
reddest region is 4K warmer than the surroundings. The colour of the GRS varies
greatly in hue, from brick red to pale salmon, and white.
There are many unanswered
questions which are puzzling scientists:
§ What
is the reason for existence of this storm for more than 400 years?
§ How
long will this storm last?
§ What
is the reason for the varying colour of the storm?
We can see that the Great
Red Spot is a field where large amount of study is required. Scientists believe
that understanding it fully will help them in knowing the Jupiter in great
details.
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