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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WEAK MAX: The weakest Solar Max in 100 years continues today with another 24 hours of quiet. None of the sunspots on the Earthside of the sun are actively flaring. NOAA forecasters estimate a scant 1% chance of M- or X-class solar flares. Solar flare alerts: text, voice.
OHIO FIREBALL: Last night, a meteor exploded in the skies above the US midwest. Witnesses report shadows cast upon the ground, unusual sounds, and a swirling contrail marking the aftermath of the blast. A NASA all-sky camera in Hiram, Ohio, recorded the fireball at 11:33 pm EDT:
"This was a very bright event," reports Bill Cooke of NASA's Meteoroid Environment Office. "Flares saturated our meteor cameras, and made determination of the end point (the terminus of the fireball's flight through the atmosphere) virtually impossible. Judging from the brightness, we are dealing with a meter class object."
Data from multiple cameras shows that the meteoroid hit Earth's atmosphere traveling 51 km/s (114,000 mph) and passed almost directly over Columbus, Ohio. Cooke has prepared a preliminary map of the ground track. According to the American Meteor Society, the fireball was visible from at least 14 US states.
Stay tuned for updates about this event.
Realtime Space Weather Photo Gallery
COMET ISON APPROACHES MARS: In two months, Comet ISON will make a spectacular flyby of the sun. First, though, it has to fly by Mars. The sungrazing comet is approaching the Red Planet for a 0.07 AU close encounter on October 1st. Mars satellites and rovers will have a close-up view. A video from NASA details the encounter.
Amateur astronomers on Earth can watch, too. Using a remotely controlled 14-inch telescope in New Mexico, Rolando Ligustri photographed ISON approaching Mars on September 28th:
At closest approach on October 1st, Mars and Comet ISON will be approximately 2o apart. While Mars is visible to the unaided eye (it shines almost as brightly as a first-magnitude star), ISON is definitely not. The comet is still far from the sun and, as it crosses the orbit of Mars, it has not yet warmed enough to reach naked-eye visibility. Reports of the comet's brightness vary from 12th to 14th magnitude, which means a mid-sized backyard telescope is required to see it.
Mars and ISON rise together in the eastern sky a couple of hours before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Visually, Mars will be easy to find on the mornings of closest approach, not only because the planet is relatively bright, but also because the crescent Moon will be passing right by it. Sky maps: Sept. 28, 29, 30; Oct. 1, 2.
New images of the comet are coming in every day. Browse the gallery for the latest views:
Realtime Comet ISON Photo Gallery
EQUINOX AURORAS: For reasons reseachers don't fully understand, auroras love equinoxes. At this time of year, even small gusts of solar wind can spark colorful lights around the poles. Last night, these green auroras appeared over Kvaløya Island near Tromsø, Norway:
"Because of the nice and warm north Scandinavian autumn, no lakes and ponds are frozen this year," says photographer Anne Birgitte Fyhn. "So tonight Jupiter, Castor and Pollux accompanied the auroras reflecting in this little lake."
The solar wind blowing past Earth today is relatively slow, only ~280 km/s. As a result, NOAA forecasters estimate a slim 10% chance of polar geomagnetic storms over the weekend. That might be enough, however, for more equinox auroras. Stay tuned. Aurora alerts: text, voice.
Realtime Aurora Photo Gallery
Realtime Noctilucent Cloud Photo Gallery
[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011]