A lot many changes are taking place on Jupiter’s surface. Experts come to know of them from Hubble Space Telescope, whose job is to observe how the Solar System’s outer planets are changing over the period of time.

According to Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Maryland, recent NASA Hubble Space Telescope observations confirm the Great Red Spot now is approximately 10,250 miles across, less than half the size of some historical measurements.

Jupiter, the largest planet in our solar system, is a gas giant dominated by hydrogen with some helium and smaller amounts of other gases, a mixture that resembles the composition of the early solar nebula and results in some staggeringly beautiful weather.

But one of the most recognizable and persistent features of Jupiter's atmosphere is the Great Red Spot (GRS). Swirling around the planet's southern hemisphere, it covers a huge 10 degrees of latitude.

This vast anticyclonic (high pressure) storm system has been observed raging for perhaps 350 years -- the first likely observations were reported in 1664-1655 by Robert Hooke and Gian-Dominique Cassini. It is cooler than its surroundings, rotates anticlockwise with a four to six day period, and is located between zonal winds moving at 100 meters per second.

The Great Red Spots on Jupiter have been found to be shrinking and for the first time, a baro-clinic wave has been seen on the planet. Amy Simon, a planetary scientist at NASA’s Goddard Space Flight Centre, said that whenever they observe Jupiter, they get hints that something is going on there.

The Great Red Spots, a gigantic hurricane, has been found to be continuing in its shrinking phase. As per the experts, Jupiter’s Great Red Spot’s extended axis is around 150 miles shorter than what it was in 2014.

"In our new observations it is apparent very small eddies are feeding into the storm," said Simon. "We hypothesized these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot."

Recently, scientists have also said that the storm might be winding down even faster than what was thought before. Experts said that the storm is getting more and more orange and its intensity is on decline and the shape is getting rounder.

Study’s co-author Glenn Orton of NASA’s Jet Propulsion Laboratory said that the Great Red Spot is due to Jupiter being called as a gas giant. In reality, the planet is much more than a huge ocean of hydrogen.

NASA's Juno spacecraft is hurtling toward Jupiter now, due to reach the giant planet in July 2016. Point-blank examination by Juno's instruments will undoubtedly help unravel the mystery.

There are other changes in the Jovian atmosphere, too. The Hubble observations show a new wave structure about 16 degrees north of Jupiter's equator, in a region of cyclones and anticyclones.

The jury is still out, but continued observations by the annual OPAL campaign, combined with in-situ measurements of the atmospheric dynamics and interior structure, may yet reveal intriguing new clues.

Other changes seen in the Jupiter’s atmosphere is a new wave structure, which may be a sign of the birth of a new cyclone there.