Juno reached perijove (the point at which an orbit comes closest to Jupiter's center) on July 10 at 6:55 p.m. PDT (9:55 p.m. EDT). At the time of perijove, Juno was about 2,200 miles (3,500 kilometers) above the planet's cloud tops. Eleven minutes and 33 seconds later, Juno had covered another 24,713 miles (39,771 kilometers), and was passing directly above the coiling, crimson cloud tops of the Great Red Spot. The spacecraft passed about 5,600 miles (9,000 kilometers) above the clouds of this iconic feature.Astronomy Photo of the Day, processed by Sean Doran of the Planetary Society.
The Great Red Spot is the oldest continually-studied storm in the solar system, dating back to the first telescopes capable of resolving the disk of Jupiter with enough detail. There are credible reports that it could be a feature observed by Italian astronomer Gian Domenico Cassini in 1665. For observers today, it's easy to see in a small telescope, although its color tends to not be red, but varies from a pink to shades that appear more gray from Earth. It's also getting smaller.
In the late 19th century the length of the spot was about 48,000 km (30,000 miles), and since then the spot has been shrinking. The Voyager spacecraft measured the spot’s length at 23,000 km (14,500 miles) in 1979. Since 2012 the spot has become more circular and has been shrinking at a faster rate of about 900 km (580 miles) per year.The massive storm was measured at 10,160 miles wide (16,350 kilometers) on April 15. That's about 1.3 times the diameter of planet Earth.
The picture is full of tremendous details, knots, swirls, twists, veinous-looking clouds and the appearance of storms within the the bigger storm. It's not simply a Jovian hurricane; it's far more complex than that.