Jupiter's Great Red Spot is an anticyclonic storm. This type of storm is a weather storm where winds around the storm form contrary to the Coriolis effect. It is located at 22 degrees south of Jupiter's equater. This storm is large enough to be seen with a telescope from the Earth's surface. It has lasted for at least 400 years. Some experts speculate that it has been going on for much longer.
The Great Red Spot of Jupiter was probably discovered in the year 1665 by Giovanni Cassini.(an Italian born astronometer). Some experts believe it may have been discovered a year earlier in 1664 by Robert Hooke. (an English natural philosher who also played and important role in the world of science). It is most likely that Robert Hooke discovered the Great Red Spot in 1664 and Giovanni Cassini actually spent the time required to properly observe it in 1665. Cassini's study of the Great Red Spot allowed him to calculate the speed of Jupiter's with remarkable accuracy.
The Great Red Spot travels in a counterclockwise motion and takes around six earth days to make a complete rotation. Measurements taken over time show that this storm can reach wind speeds of up to 300 miles per hour.
Jupiter's Great Red Spot is between 24,000-40,000 kilometers from west to east and between 12,000-14,000 kilometers from south to north. It is big enough to hold between two and three planets the size of the earth.
Scientists at the University of California Berkeley did a study that showed the Great Red Spot had decreased by fifteen percent in diameter along it's axis. It it not however in any danger of disappearing for a really long time.
Infrared (relating to the range of invisible radiation wavelengths) data indicates that the Great Red Spot is colder than the other cloud masses on Jupiter. This is because it is higher in altitude.They are about 8 kilometers higher than the other cloud masses.
The Great Red Spot most likely gets its red color from organic molecules such as red phosphorus or sulfur. The red color ranges from dark brick red to pale pink and even white.
There are two other red spots that have formed on Jupiter it the last several years. It is possible that one of them could replace The Great Red Spot in the distant future.