Back around 1916, two small (weâ€™re talking half the size of Earth here), but not uncommon, little white oval-shaped storms were observed close together in Jupiterâ€™s southern hemisphere. In 1939, a third similar storm appeared, and while interesting, it wasnâ€™t what youâ€™d really call news, especially if a nearby and much bigger astronomical item was distracting you at the time — The Great Red Spot (GRS). It wouldâ€™ve been understandable; after all, the GRS storm is almost three times the size of the Earth, has winds in excess of 250 miles per hour, and has had people wondering at it for well over 400 years — ever since Giovanni Cassini and Robert Hooke first trained their telescopes on it between 1662 and 1670.
In what would be comparatively considered a blink of an eye, between 1998 and 2001, and while almost no one was watching, Jupiter was brewing up a surprise for planet watchers like me. By 2000, those three little white cyclones had merged together into one big flattened oval measuring about twice the diameter of the earth and about 7,500 miles tall. Since its formation, itâ€™s grown to about half the size of its cousin — the Great Red Spot — but itâ€™s doubtful that itâ€™ll get much larger because of the opposing bands of jet stream winds shepherding it tightly to the north and south.
Even more interestingly, itâ€™s recently begun taking on its older cousinâ€™s coloring, indicating that itâ€™s whipping up material from Jupiterâ€™s lower atmosphere while it hovers high above it. The effected matter changes color after it is sucked up from below, then is chemically transformed by solar radiation and ultraviolet light. In November of 2005, astronomers noticed that it was shifting hue. By December of 2005, it had taken on a brownish color and has since turned to the same color as the GRS, possibly because itâ€™s pulling material from the same atmospheric layer as its bigger companion.