Are we alone? Your iPhone has the answer. Download the all-new Drake Equation app to calculate the population of the Milky Way.
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DISINTEGRATING COMET MOVIE: Note to comets: Stay away from the sun. On July 5th, an icy comet dove into the sun and disintegrated. New footage just released by NASA shows the final stages of the death plunge.
BIG SUNSPOTS: NOAA forecasters estimate a 40% chance of M-class solar flares today. The source would be one of three big sunspots emerging along the sun's northeastern limb. Click on the image to view a 3-day movie from NASA's Solar Dynamics Observatory:
Among the three, the leading sunspot AR1260 is most active. It has produced more than a dozen C-class flares in the past 24 hours, more than doubling the total for the entire month of July so far. New sunspot AR1262, however, could eventually cause more trouble. Magnetograms of the active region reveal a delta-class magnetic field that harbors energy for powerful X-class eruptions. Readers with solar telescopes are encouraged to monitor developments.
more images: from Achim Marian Lucian of Targu Jiu, Gorj, Romania; from Peter Desypris of Island of Syros, Greece; from Gianfranco Meregalli of Milano Italy; from Ron Cottrell of Kitt Peak National Observatory; from John Minnerath of Crowheart, Wyoming; from Cai-Uso Wohler of Bispingen, Germany
NOCTILUCENT CLOUDS: "The morning of July 26th was electric blue!" says Heiko Ulbricht of Freital, Saxony, Germany. "I woke up at 3 clock, looked out my bedroom window to the north and saw a stunning display of noctilucent clouds." Moments later, he dashed outside with a camera to record the view:
July has been an odd time for noctilucent clouds (NLCs). The month began with an extravagant display that stretched as far south as Colorado and Kansas--odd because NLCs are usually confined to higher latitudes. The event seemed to herald a period of widespread sightings. Observers were disappointed, though, when the clouds quickly retreated to their usual northern habitat. Could this German apparition signal renewed activity? Sky watchers at all latitudes should be alert for electric-blue ripples around sunrise and sunset. Observing tips may be found in the gallery.
more images: from Timo Newton-Syms of Helsinki, Finland
2011 Noctilucent Cloud Gallery
[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009]
June 2011 Aurora Gallery
[Aurora alerts: text, voice] [previous Junes: 2010, 2008, 2001]
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 July 28, 2011 there were 1237 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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