MT. REDOUBT ERUPTS: After months of teasing seismic activity, Alaska's Mt. Redoubt finally erupted on March 23rd. The blast hurled clouds of ash into the lower stratosphere at least 18 km high. The last time an Alaskan volcano blew its top (Kasatochi in August 2008), stratospheric aerosols caused fantastic sunsets around the northern hemisphere--a phenomenon that could recur in the days and weeks ahead. Mt. Redoubt isn't finished. "A large explosion may occur again at anytime," says the Alaska Volcano Observatory. Stay tuned for updates. SATELLITE WRECKAGE: Last month, the Iridium 33 communications satellite was completely destroyed when it collided with Russian satellite Cosmos 2251. Or was it? Satellite observer Marco Langbroek has observed a substantial piece of Iridium 33 wreckage apparently still intact tumbling over the Netherlands: Photo details: Canon EOS 450D + EF 50/2.5 Macro lens "This photo is one of two I shot on March 20th showing Iridium 33 flashing at magnitude +2 with a period of 4.6 to 4.7 seconds," says Langbroek. "Simone Corbellini in Italy and I have independently observed it occasionally giving off much brighter flashes of magnitude -2. Simone thinks that the main mission antennas are still intact and glinting in the orbital sunlight." "It seems that Iridium 33 received a glancing blow," he suggests. "Pieces scattered off, but there is still a considerable body left." Readers, if you would like to try to observe the wreckage, check the Simple Satellite Tracker for flyby times. You might see nothing when Iridium 33 passes overhead, but the possibility of a bright flash makes it worth a try. SOMETHING MYSTERIOUS IN THE STATE OF DENMARK: On March 20th, Danish photographer Jesper Gronne looked up at the clouds and saw not just one or two but three concentric halos around the sun. Before the rare display could fade, he grabbed his camera (a Canon 5D) and snapped more than 20 pictures. Stacking the images on his computer yielded a pin-up quality record of the event: "I never expected to see such a rich variety of ice halos here in lowland Denmark--and it's not even winter anymore!" he marveled. What could cause such an apparition? Atmospheric optics expert Les Cowley explains: "We can work outwards from the sun to explore the mysteries of this display. The first ring is an exceptionally bright and rare 9-degree halo made by tumbling pyramidal ice crystals in the clouds. The same crystals also produced displays on the other side of the North Sea the night before. The inner halo's bright upper and lower patches could be something very rare indeed, plate arcs from aligned pyramids. But we must be cautious, they could just be spots of thicker cloud!" "The next bright ring is at first sight the common 22-degree halo but with so many pyramidal crystals about it could also be a combination of other pyramidal halo rings. There are hints too of 18 degree pyramidal halos inside it. At least the two sundogs are familiar sights!" "Farther from the sun at top is another familiar halo, the ‘smile-in the-sky' circumzenithal arc made from ordinary ice plates. But the one touching it and curving downwards is another mystery. We know it is either a supralateral arc or a 46 degree halo. But if a supralateral, we would expect an upper tangent arc from the same column crystals – there is none. If a 46 degree halo then the inner 22 degree ring should be much brighter! Displays like this one are fascinating and need long studies of many photos to unravel and be sure of their secrets." March 2009 Aurora Gallery [previous Marches: 2008, 2007, 2006, 2005, 2004, 2003, 2002] Comet Lulin Photo Gallery [Comet Hunter Telescope: review] [Comet Lulin finder chart] Explore the Sunspot Cycle |