Metallic photos of the sun by renowned photographer Greg Piepol bring together the best of art and science. Buy one or a whole set. They make a stellar gift.
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CHANCE OF MAGNETIC STORMS: NOAA forecasters estimate a 45% chance of geomagnetic activity on June 4th when an incoming solar wind stream and a CME might deliver a double blow to Earth's magnetic field. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice.
NOCTILUCENT CLOUDS OVER EUROPE: The 2011 noctilucent cloud (NLC) season has begun. For the past few nights, observers across northern Europe have spotted velvety, electric-blue tendrils rippling across the sunset sky. John Houghton sends this picture from Newtown Linford, Leicester, UK:
"This was the best display of noctilucent clouds I've seen to date," he says. "It was visible even before sunset."
NLCs are a summertime phenomenon. In the upper atmosphere, 80+ km high at the edge of space itself, tiny ice crystals nucleate around microscopic meteoroids and other aerosols; when the crystals catch the rays of the setting sun, they glow electric blue. Ironically, these highest and coldest of clouds form during the warmest months on the ground.
Noctilucent clouds first appeared in the 19th century after the eruption of super-volcano Krakatoa. At the time, people thoght the clouds were caused by the eruption, but long after Krakatoa's ash settled, the clouds remained. In those early days, NLCs were a polar phenomenon, mainly seen in far-northern places such as Scandinavia or Alaska. In recent years they have intensified and spread with sightings as far south as Utah and Colorado. A NASA spacecraft named AIM is in orbit to investigate.
Readers, especially you at high latitudes, be alert for NLCs in the evenings ahead. Observing tips may be found in our 2009 Noctilucent Cloud Gallery.
more images: from Martin McKenna of Maghera, Co. Derry, N. Ireland; from Jesper Gronne of Silkeborg Denmark; from Paul Martin of Pigeon Top, Omagh, Northern Ireland
ECLIPSE OF THE MIDNIGHT SUN: A solar eclipse at midnight? It's not only possible, it actually happened this week. On June 1st, the new Moon passed in front of the midnight sun above the Arctic circle, producing a partial eclipse of exquisite beauty. And, yes, we're talking about the sun:
Bjørnar G Hansen photographed the eclipse and an onlooker from Sommarøy, Tromsø, Norway--a rare and lovely event indeed. According to NASA calculations, this won't happen again for 73 years. Until then, browse the gallery.
Midnight Solar Eclipse Gallery
[NASA: A Rare Eclipse of the Midnight Sun]
more images: from Travis Stagg of Fairbanks Alaska; from B.Art Braafhart of Sallatunturi, Finnish Lapland; from Thomas Hagen of Tromsø, Norway; from Johan Kero of Bergfors, Kiruna, Sweden; from Joerg Schoppmeyer of Akureyri, Iceland;
April 2011 Aurora Gallery
[previous Aprils: 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003, 2002]