The plume of gas is enormous, stretching more than 10,000 km from the central storm to a nearby jet stream that appears to be carrying it away. Wesley says that currently such a streamer is peeling off every week or so.
The Great Red Spot is the biggest storm in the solar system–an anticyclone wider than Earth with winds blowing 350 mph. Astronomers have been observing it for hundreds of years. In recent decades, the Great Red Spot has been shrinking. Once it was wide enough to swallow three Earths; now only one of our planet could fit inside the maelstrom. This has led some researchers to wonder if the GRS could break up or disappear within our lifetimes. Perhaps the streamers are part of this process.
In fact, such unraveling clouds have been seen before. For instance, the Gemini North adaptive optics telescope on Maunakea saw a lesser but similar streamer in May of 2017:
"Events like this show that there's still much to learn about Jupiter's atmosphere," said Glenn Orton of NASA's Jet Propulsion Laboratory in a press release about he 2017 streamer.
Wesley describes how the streamers are behaving now: "Each streamer appears to disconnect from the Great Red Spot and dissipate. Then, after about a week, a new streamer forms and the process repeats. You have to be lucky to catch it happening. Jupiter spins on its axis every 10 hours and the GRS is not always visible. A joint effort between many amateurs is underway to get clear images of the process."
Now is a great time to monitor the action. Jupiter is approaching Earth for a close encounter in June 2019. In the weeks ahead, Jupiter will shine 4 times brighter than Sirius, the brightest star in the sky, and even small telescopes will reveal its storms, moons, and cloud belts. You can find Jupiter in the constellation Ophiuchus in the southern sky at midnight: sky map.
