The Great Red Spot (GRS) on Jupiter is a big deal, literally. A high-pressure storm similar to a hurricane on Earth, its girth would swallow two Earths with room to spare. This photo shows the recent development of a string of smaller vortices or eddies following the Spot captured by Philippine astrophotographer Chris Go. My first thought was how akin it was to photos we’ve all seen of a mother duck followed by her babies. Not that the GRS necessarily had anything to do with the creation of these little red ovals, but there’s often turbulence in its vicinity. I wouldn’t be surprised if it’s somehow involved in their creation. Either way, mama spot and babies make a picturesque presentation.
All this fresh activity is located in the planet’s southern latitudes, a region prone to storms, spots and ovals. The Great Red Spot is arguably Jupiter’s most defining feature. ItsÂ clouds are some five miles higher than their surroundings and rotate counterclockwise as a single system in about six days. Amazing to realize this storm’s been around for at least 350 years! It was first observed by French astronomer Jean-Dominique Cassini in 1655. The “baby reds” are smaller eddies of spinning clouds tracking along Jupiter’s south tropical zone, where winds can blow up to 250 mph.
In other Jupiter news, the little white spot that marked the start of new activity in Jupiter’s southern equatorial belt (SEB) earlier this fall, appears to be fueling the belt’s resurgence. You’ll recall that less than a year ago Jupiter “lost its stripe”as the SEB faded to near invisibility. Winds are now spreading darker material derived from below the pale white cloud deck into a dark, wispy streak. A clear night, steady skies and high power should reveal the feature to observers with modest-sized telescopes. I’m waiting for successive snow storms to finally blast out of the region and leave a couple calm, clear nights in their wake, so I can check it out again myself. Tomorrow I’ll post a list of times when you can see it best.
The moon now rises after the end of twilight. You guessed it – dark skies are back. We’ll have just over an hour of complete darkness tonight – from about 6 to 7 p.m.Â – before moonrise. Why not go out and watch what’s left of the summer stars slink down in the western sky? Improbable as it sounds, the Summer Triangle of Vega, Altair and Deneb is still well-placed for viewing during the early evening. Heck, Deneb, at the top of the cross, is 70 degrees high (about 3/4 the way up the sky) at 6:30 p.m. It’s the brightest star in the constellation Cygnus the Swan, more familiar to many of us as the Northern Cross. If you live where there’s little city light pollution, the star clouds of the Cygnus Milky Way are especially pronounced compared to the galaxy’s dimmer reaches in the winter constellations of Auriga (awe-RYE-guh) and Orion.
The Summer Triangle, like the Big Dipper, is not a true constellation but an asterism – it’s comprised of the brightest stars in three neighboring constellations. It’s also a seasonal marker. When we see the Triangle first appear in the eastern sky, it tells us spring will soon give way to summer. When due south at nightfall, summer is already ripening into fall, and when the Cross stands straight up in the west after dinnertime, the first snow has whitened the ground … or will soon.