It seems to be a day for carelessness. First Apple loses another iPhone prototype, and now Jupiter's lost a belt.
One of the first to spot the change was blogger Astrobob.
"That bad boy south equatorial belt (SEB) has completely faded away. Point your scope at the planet any morning soon and you'll see only one obvious dark stripe, the North Equatorial Belt," he says on his blog.
"Jupiter with only one belt is almost like seeing Saturn when its rings are edge-on and invisible for a time - it just doesn't look right."
The belts are composed of ammonia ice, with a little sulfur and phosphorus thrown in. Scientists aren't quite sure how to account for them - one theory is that they are simply gaps in higher, paler clouds that allow the darker, deeper levels to show through.
It's not the first time the belt has disappeared - indeed, it happens every three to fifteen years. it last went missing in the early 1990s, and before that in 1973.
This time, though, the disappearance happened as the planet spent a three-month period behind the sun, so that on its emergence the transformation appears rather more sudden.
Over the next few months, we can expect to see a white spot appear which will gradually get stretched out by the planet's 350mph winds to form a new SEB.
Australian astronomer Anthony Wesley has captured the transformation - check out more of his pictures here.