Big, Bright Two-Spotted Jupiter Dominates the Evening Sky

AOL Research and Learn: Sky & Telescope | May 1, 2006

Look southeast after dark this month, and you’ll see a bright white “star” looking right back at you. This is the planet Jupiter, shining so brightly that you can’t help but notice it even through city light pollution.

Jupiter blazes so bright mostly because it’s a big planet, but also because on May 3 it is at opposition: positioned opposite the sun in our sky and at its nearest to Earth for the year. Jupiter will remain nearly as bright for the rest of May and throughout the coming summer, since it doesn’t get much farther from us even several months after opposition. It will be the “star” of all the warm-weather nights in 2006.

Telescope users have been following a strange event brewing on Jupiter. Amid the planet’s cloud belts, a long-enduring “white oval” unexpectedly turned reddish last February—matching the color of Jupiter’s centuries-old Great Red Spot. Both amateur and professional astronomers have been tracking “Red Spot Junior.”

Jupiter’s spots are enormous cyclonic storms somewhat like hurricanes on Earth. White ones are topped by clouds of ammonia crystals in Jupiter’s super-cold upper atmosphere. The reddish tints, planetary astronomers believe, arise from contaminant compounds of sulfur, phosphorus, or hydrocarbons welling up from inside Jupiter’s mysterious, gaseous interior.

To see the Great Red Spot and “Red Spot Junior,” you’ll need a large amateur telescope with high-quality optics. Jupiter rotates once every 9 hours 56 minutes; a list of times when the Great Red Spot crosses Jupiter’s centerline, as seen from Earth, can be generated online for any date at redspot. “Red Spot Junior” follows behind about 1 hour 10 minutes after the Great Red Spot. Examples: on May 3, the Great Red Spot is centered at 10:35PM ET; on May 12, at 9:57PM PT.