New images taken
by the Hubble telescope prove that the Great Red Spot is more dynamic than previously thought. Some of the effects are related to the 90-day cycle.
The largest planet in the solar system is also home to its largest cyclones, and the most notable of these is the Great Red Spot, which is not a cyclone like, say, Earth's hurricanes, but an anticyclone that rotates in the opposite direction.
It is large enough to swallow the Earth whole, and has existed for at least 150 years. The exact age is not known, even early 17th century telescopes detected the cyclone on Jupiter, but today it is unclear whether it is indeed the Great Red Spot.
Even today, this cosmic storm still leaves mysteries for science. The Hubble Space Telescope took multiple images of Jupiter between December 2023 and 2024. In doing so, a previously unknown ripple of the storm could be spotted, according to a new study published in The Planetary Science Journal.
We are talking about a 90-day cycle, which was already known. However, only the fluctuations in the storm's westward movement were known. "We did not expect its size to fluctuate; to our knowledge, it has not yet been described," said planetologist Amy Simon, who works at the Goddard Space Flight Center at the U.S. space agency NASA.
These changes appear to be related to the speed of travel, she said, and Hubble's high resolution suggests that the storm is definitely shrinking and expanding as it moves faster and slower. There is currently no hydrodynamic explanation for this.
The fact that it is Hubble that is contributing to the rediscovery of such a well-known and well-studied object as the Great Red Spot is surprising. Hubble has long been targeting Jupiter every year as part of a program called Opal, led by Simon. However, the new data comes from a program specifically designed for the Great Red Spot.
The ripple fits in with a number of other dynamics of the storm. "If we look closely, we can see that a lot of things change from day to day," Simon says. Some of those changes appear to be related to the 90-day cycle. The center of the Great Red Spot becomes brighter in ultraviolet light at the time of its greatest expansion. This indicates changes in the fog cover in the upper atmosphere.