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DAWN'S SMOOTH MOVE: NASA's ion-propelled Dawn spacecraft entered orbit around Vesta last month in an unusual way. Today's story from Science@NASA explains Dawn's smooth move and unveils the first full-frame image of the giant asteroid. Click here.
GEOMAGNETIC ACTIVITY: A solar wind stream is buffeting Earth's magnetic field and causing intermittent geomagnetic activity around the poles. The peak so far has been a G1-class storm that lasted for several hours around the end of July 30th. "I received a storm alert from Space Weather Phone," says Bob Johnson of Saskatoon Saskatchewan. "When I dashed outside, there were big-time auroras." He recorded the scene in this 25-second exposure:
NOAA forecasters estimate a ~20% chance of more such storms on July 31st as the solar wind continues to blow. High-latitude sky watchers should remain alert for auroras especially in the southern hemisphere where skies are winter-dark. Aurora alerts: text, voice.
July 2011 Aurora Gallery
[previous Julys: 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003]
TODAY'S BONUS SHOTS: ISS-Sunspot Conjunction from Agnieszka and Friedrich Deters of Minneapolis, MN; Iridescent Cloud from Pete Lawrence of Selsey, West Sussex, UK
SUNSPOT SUNSET: The biggest sunspots of Solar Cycle 24 are showing themselves through the clouds at sunset. "Yesterday evening we had a nice view of AR1260, AR1261, and AR1263 from my farm east of Plymouth, Iowa," says Steve Yezek. Two of them are circled in this snapshot:
Caution: Even when the sun is dimmed by low-hanging clouds or haze, focused sunlight can still damage your eyes. Do not look at the sun through unfiltered optics of any kind. A White Light Solar Observing System is the best way to monitor these great sunspots.
Sunspot 1261 has a "beta-gamma-delta" magnetic field that harbors energy for X-class solar flares. Any such eruptions today would be geo-effective as the sunspot is squarely facing Earth. Solar flare alerts: text, voice.
more images: from M.Taha Ghouchkanlu of Kashan, Iran; from Alan Friedman of Buffalo, NY; from David Cortner of Rutherford College, NC; from John Stetson of Falmouth, Maine
2011 Noctilucent Cloud Gallery
[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009]
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 August 1, 2011 there were 1241 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 |
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