When is the best time to see auroras? Where is the best place to go? And how do you photograph them? These questions and more are answered in a new book, Northern Lights - a Guide, by Pal Brekke & Fredrik Broms.
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THE FULL MOON AND SATURN: When the sun goes down tonight, step outside and face east. The golden "star" next to the rising full Moon is Saturn. Saturn and the Moon will be up, together, all night long. Saturn's rings and lunar mountains are easy targets for small telescopes. Take a look!
BIG SUNSPOT, CHANCE OF FLARES: Sunspot AR1726 is turning away from Earth, but the threat of flares is not subsiding. The sunspot has a delta-class magnetic field that harbors energy for powerful eruptions. NOAA forecasters estimate a 40% chance of M-class flares and a 15% chance of X-flares on April 25th. Solar flare alerts: text, voice.
Amateur astronomer Alan Friedman photographed the sunspot on April 23rd. His H-alpha telescope, tuned to the red glow of solar hydrogen, revealed a seething active region spanning more than 125,000 km (10 Earth diameters) wide:
"The full-sized image reminds me of a Clementine orange," notes Friedman. "I captured the fruity shot through a turbulent jet stream on a beautiful spring day in Buffalo, NY."
The sheer size of the sunspot makes it an easy target for backyard solar telescopes. Browse the gallery for views from around the world.
Realtime Space Weather Photo Gallery
ELLIPTICAL MOON HALOS: The moon is waxing full, which means now is the time to be alert for icy moon halos. On April 22nd, Darryl Luscombe of Sointula, British Columbia, saw an unusual specimen. Instead of being circular, as usual, this halo was elliptical:
"I dont think I have ever seen an elliptical halo around the moon before," says Luscombe. "I looked up and just stared for about a minute. Then I raced inside to get my camera. I just managed to photograph it before it disappeared."
Atmospheric optics expert Les Cowley comments on the apparition: "There have been quite a few ellipticals seen in the last few weeks both in Europe and the US. Something strange [is happening] in all our skies!"
"These unusual ice halos are much smaller than the ordinary 22 degree halo encircling the sun or moon," Cowley continues. "In the 22 degree halo the ring is effectively made by light refracting through a 60 degree ice prism. The smaller elliptical halos need much narrower prisms and we think that six sided plate shaped crystals with very shallow pyramidal ends might do the work. The problem is that such crystals are unphysical and computer simulations using them do not predict the halo very well. An alternative is the wedge shaped sections of small snowflake-like crystals. Whatever their cause, they are rare and mysterious!"
Realtime Space Weather Photo Gallery
LYRID FIREBALLS: For the past few days, Earth has been passing through a stream of debris from ancient Comet Thatcher, source of the annual Lyrid meteor shower. According to international observers, the encounter produced as many as 25 meteors per hour. Some of these were fireballs. NASA's All Sky Fireball Network detected more than 30 Lyrids as bright as Venus on the nights around the shower's April 22nd peak. Here are their orbits:
In the diagram, the red splat marks the location of Earth; green elipses are the orbits of the meteoroids, triangulated by multiple cameras in the meteor network.
"The purple ellipse is the orbit of Comet Thatcher," adds Bill Cooke, lead scientist for NASA's Meteoroid Environment Office. "The orbits of the comet and the meteoroids match up nicely." According to Cooke, the Lyrid fireballs penetrated Earth's atmosphere as deeply as 44 miles above the planet's surface, traveling at an average speed of 105,000 mph.
The shower is subsiding now as Earth exits the debris stream.
Realtime Meteor Photo Gallery
Realtime Aurora Photo Gallery
Realtime Comet Photo Gallery
Realtime Noctilucent Cloud Photo Gallery
[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011]