October 18, 2012
Amateur Astronomers Help Experts Keep Tabs On Tumultuous Jupiter
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In ancient Rome, Jupiter was the King of the gods and the god of sky and thunder with his mighty thunderbolt. He would certainly be pleased with the changes occurring on his namesake planet. Jupiter the planet is continually being peppered with small space rocks, the atmosphere is changing colors in wide belts, hotspots are vanishing and reappearing, and clouds are gathering and dissipating over various regions.
An international team of scientists led by NASA's Jet Propulsion Laboratory (JPL) has been studying the changes, and their findings were presented at the American Astronomical Society's Division for Planetary Sciences Meeting in Reno, Nevada.
"The changes we're seeing in Jupiter are global in scale," Glenn Orton, senior research scientist at JPL, said. "We've seen some of these before, but never with modern instrumentation to clue us in on what's going on. Other changes haven't been seen in decades, and some regions have never been in the state they're appearing in now. At the same time, we've never seen so many things striking Jupiter. Right now, we're trying to figure out why this is all happening."
Orton and his colleagues have been taking images and maps of Jupiter at infrared wavelengths from 2009 to 2012. They compared these images with high-quality visible images from the increasingly active amateur astronomy community. First they observed a fading and return of the brown-colored South Equatorial Belt from 2009 to 2011. Then they noticed the same fading and darkening of the North Equatorial Belt, which grew whiter in 2011 to an extent not seen in more than 100 years. In March 2012, the belt started darkening again.
New data was obtained from NASA's Infrared Telescope Facility and the Subaru Telescope on Mauna Kea matched up that activity with the infrared observations of the Northern Belt. In the Northern Equatorial Belt, the deeper cloud decks simultaneously thickened, but not the upper cloud deck. In the South Equatorial Belt, both levels of clouds thickened, then cleared up. Brown, elongated features in the whitened area called "brown barges" were resolved by the infrared data as distinct features. They were revealed to be regions clearer of clouds and probably consist of downwelling, dry air.
The team also focused on a series of blue-gray features along the southern edge of the North Equatorial Belt, which appear to be the clearest and driest regions on the planet. They show up as apparent hotspots in the infrared view, revealing the radiation emerging from a deep layer of Jupiter's atmosphere. Coincident with the whitening and darkening of the North Belt, the hotspots disappeared from 2010 to 2011, but reestablished themselves by June of 2012.
A number of objects have hurtled through Jupiter's atmosphere, creating fireballs that were visible to amateur astronomers on Earth. Three of these, probably less than 45 feet in diameter each, have been observed since 2010. On September 10, 2012, the latest object struck — though infrared investigation of these events showed that this one was relatively harmless, unlike earlier strikes in 1994 or 2009.
"It does appear that Jupiter is taking an unusual beating over the last few years, but we expect that this apparent increase has more to do with an increasing cadre of skilled amateur astronomers training their telescopes on Jupiter and helping scientists keep a closer eye on our biggest planet," Orton said. "It is precisely this coordination between the amateur-astronomy community that we want to foster."
Image 2 (below): Images in the visible-light and infrared parts of the spectrum highlight the massive changes roiling the atmosphere of Jupiter. Image credit: NASA/IRTF/JPL-Caltech/NAOJ/A. Wesley/A. Kazemoto/C. Go