The Great Red Spot Puzzling Astronomers for more than 400 Years

The great red spot of Jupiter
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 anticyclonic, it is a high-pressure storm opposite to the cyclones present on Earth. It is also called the eye of. The GRS is a very old storm and first observed and described by Giovanni Cassini in 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 with 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

At the 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 the 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 the wind at the edge of the 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 the storm is higher than the neighboring 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 the ground and get slow down.

The other interesting feature of the GRS is its color. The most popular theory, which is supported by laboratory experiments claims that the color of the red spot is caused by complex organic molecules, red phosphorus, or other sulfur compounds. The reddest region is 4K warmer than the surroundings. The color 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 the existence of this storm for more than 400 years?
  • How long will this storm last?
  • What is the reason for the varying color of the storm?

We can see that the Great Red Spot is a field where a 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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