Centuries ago, a huge red spot on Jupiter vanished ... For over 150 years, the Great Red Spot has continued to shrink. In 1879, when it appeared more sausage-like, it was some 24,200 miles ...

An 1879 observation placed the size of the spot ... In 1665, Italian astronomer Giovanni Cassini observed a giant dark spot on Jupiter, which he called the "Permanent Spot." ...