The Great Red Spot, visible on Jupiter, is an anticyclonic swirling storm that can be seen. It is the largest in the Solar System and large enough to accommodate our entire planet. A new analysis now shows that the winds surrounding the spot are speeding up mysteriously.
Researchers used data from the Hubble Space Telescope to examine the patterns of storms from 2009 to 2020. They measured an 8 percent increase in wind speed at the outer edge over this time period.
This is an increase of just 2.5 km (1.5 miles) per hour in every year that measurements were made. Although it's not huge, it's significant and can only be measured because Hubble has high-resolution imagery.
Speeds of the inner and outer ring winds. (Wong et al, Geophysical Research Letters, 2021)
"When I first saw the results, my first question was, 'Does it make sense?' Michael Wong, a planetary scientist at the University of California, Berkeley, says that no one has seen anything like it before.
This is something Hubble can only do. This revelation is possible because of Hubble's long-term observations and continued observation.
To reach their conclusions, the researchers developed a new type of data analysis. They used modeling software to evaluate up to tens to thousands of wind vectors (individual directions or speeds) for every time Hubble was able photograph Jupiter.
The storm's edges are now moving at speeds of up to 398 miles per hour (640 km) in counterclockwise directions. It is time to ask the question: What's causing this acceleration? There's no simple answer.
The study and collected data did not rule out some possibilities. However, neither changes in wind shear (or angle), from the surrounding atmosphere, or changes in temperature at different altitudes were thought to be the cause. Experts are still trying to determine the cause.
Wong says, "That's difficult to diagnose because Hubble can't view the bottom of storm very well." "Anything below cloud tops is inaccessible in the data. But it's an interesting piece to the puzzle that can help us understand the Great Red Spot's energy and fuel.
Based on previous research, the Great Red Spot has been shrinking over time. This is yet another mystery that must be solved. Until more precise and detailed measurements of this storm are taken, there will be many unanswered questions.
Since the 17th century, astronomers have been studying Jupiter's most prominent feature. Continuous observations were made since 1878. It has become smaller and more circular over the years.
Even though the Hubble space telescope can't see objects larger than 170 km (106 miles), it still has a remarkablely high resolution for mapping space and charting what is happening on Jupiter.
Amy Simon, a NASA Goddard Space Flight Center planetary scientist, says, "Since there aren't storm chaser aircraft at Jupiter, it's impossible to continuously measure the winds on-site."
"Hubble is the only telescope capable of capturing Jupiter's winds in such fine detail."
Geophysical Research Letters published the research.