Listen to radar echoes from satellites and meteors, live on listener-supported Space Weather Radio.
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ANOTHER QUIET DAY: With all of the sunspots on the Earthside of the sun in decay, solar activiy is low. NOAA forecasters estimate a slight 1% chance of strong solar flares during the next 24 hours. Solar flare alerts: text, voice.
SOLAR WIND: A medium-speed (~450 km/s) solar wind stream is blowing past Earth. The action of this weak stream is not enough to trigger full-fledged geomagnetic storms, but it is enough to ignite auroras around the Arctic Circle. Frank Olsen of Sortland, Norway, took this picture during the early hours of Dec. 4th:
The odds of a gomagnetic storm today remain low--only 5% to 15% according to NOAA--but more Arctic lights are in the offing as the solar wind contiinues to blow. Check the aurora gallery for updates.
Realtime Aurora Photo Gallery
GHOSTLY WHITE RAINBOW: Dec. 1st was a foggy night in Little Sioux, Iowa. Nevertheless, Evan Ludes decided to go outside to photograph the nearly-full Moon (and "to play in the fog," he says). The Moon was high and bright, as expected, and when he finished snapping the lunar disk, he turned around to find this ghostly white rainbow behind his back:
"It was a lunar fogbow," explains Ludes.
Fogbows are sometimes called "white rainbows," and that's about right. Both rainbows and fogbows are caused by light reflected from water droplets. When the droplets are large (rain), they act like prisms, spreading the colors wide for easy visibility. When the droplets are small (fog), the prism-action is reduced, and colors are smeared together into a ghostly-white arc.
"I also saw a fogbow created by our headlights," he adds. "It was incredibly bright visually, and this was my first time ever seeing one!"
Realtime Space Weather Photo Gallery
Realtime Noctilucent Cloud Photo Gallery
[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011]
Potentially Hazardous Asteroids (PHAs
) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones
all the time.
On December 4, 2012 there were potentially hazardous asteroids. Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.
| ||The official U.S. government space weather bureau |
| ||The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| ||Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| ||3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| ||Realtime and archival images of the Sun from SOHO. |
| ||from the NOAA Space Environment Center |
| ||the underlying science of space weather |