Great Red Spot
Also called: GRS, Jupiter's belts.
A giant storm on Jupiter, larger than Earth, that has raged for at least 190 years.
The Great Red Spot is an enormous high-pressure storm in Jupiter's southern hemisphere. It has been shrinking — once three Earths wide, it's now about 1.3 — and its colour ranges from brick red to a pale salmon. It's only visible when it's on the side of Jupiter facing us, about every other evening for a few hours.
Jupiter's dark belts and bright zones are cloud bands driven by its fast spin (under 10 hours); a light blue filter can lift their contrast.
At the eyepiece
Jupiter rotates so fast that features drift visibly in half an hour. Sketching helps your eye pick out detail.