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AURORA BOREALIS: Earth's magnetic field is mostly quiet. Nevertheless, some bright auroras were caught swirling around the Arctic Circle on Jan. 28th. Military satellites photographed the lights from above, while sky watchers in Canada saw them from ground level. An even bigger display is expected on Feb. 3-4 when an incoming solar wind stream reaches Earth.
DOUBLE ERUPTION: Jan. 28th began with not one but two major eruptions on the sun. Separated by more than a million kilometers, the two blasts occurred almost simultaneously on opposite corners of the solar disk. Click on the image to view a movie recorded by NASA's Solar Dynamics Observatory:
See the movie or browse selected high-resolution still frames: #1, #2, #3
On the lower left, a magnetic filament became unstable and erupted, hurling a portion of itself into space. On the upper right, departing sunspot 1149 produced an M1-class solar flare and a bright coronal mass ejection (SOHO movie). Is this all a big coincidence? Maybe not. New research shows that eruptions on the sun can "go global" with widely separated blasts unfolding in concert as they trigger and feed off of one another.
These blasts are going to miss in concert, too. Plasma clouds ejected by the two eruptions will sail wide of our planet, one on the left and one on the right. No Earth-effects are expected; maybe next time.
more images: from Peter Desypris of Athens,Greece; from T. Taker et al of South Portland, Maine; from Robert Arnold of Isle of Skye, Scotland; from James Kevin Ty of Manila , Philippines
V-TOPPED LIGHT PILLARS: Light pillars are a common sight around cities in winter. Urban lights bounce off ice crystals in the air, producing tall luminous columns sometimes mistaken for auroras. But the light pillars Mike Hollingshead saw on Jan. 26th near a corn mill in Blair, Nebraska, were decidely uncommon. "They had V-shaped tops," he explains, "and some of the Vs were nested." Here is what he saw:
"These light pillars are not just rare, they are exceptional!" declares atmospheric optics expert Les Cowley. "Ordinary pillars are produced by plate-shaped ice crystals roughly half way between you and the light source. These are different. Their rarely seen flared tops show that they were made by column-shaped crystals drifting slowly downwards and aligned horizontal by air resistance."
"The flares are a form of the upper tangent arcs that we sometimes see in daytime halo displays," he continues. "But even more exotic, some flares have a second one nested within them! Some ice crystal columns do not rotate but instead keep two of their prism faces improbably horizontal to give us the very uncommon Parry arcs of solar halo displays. The nested flares here are amazing and probably the light halo equivalent of Parry arcs."
January 2011 Aurora Photo Gallery
[previous Januaries: 2010, 2009, 2008, 2007, 2005, 2004]
Solar Eclipse Photo Gallery
[NASA: Hinode Observes Annular Solar Eclipse]