Turn your cell phone into a field-tested satellite tracker. Works for Android and iPhone. | | | BRIGHT CONJUNCTION: When the sun goes down tonight, step outside and look east. Jupiter and the waxing full Moon are lined up less than 10o apart. It's a beautiful conjunction that will last all night long--don't miss it! [sky map] ASTEROID FLYBY: NASA radars are monitoring 2005 YU55, an asteroid the size of an aircraft carrier, as it heads for a flyby of the Earth-Moon system later today. There is no danger to our planet. At closest approach on Tuesday, Nov. 8th, at 3:28 pm PST (23:28 UT), the 400m-wide space rock will be 324,600 kilometers away, about 85% the distance from Earth to the Moon. Professional astronomers are eagerly anticipating the flyby as the asteroid presents an exceptionally strong radar target. Powerful transmitters at Goldstone and Arecibo will ping the space rock as it passes by, revealing the asteroid's shape and texture in crisp detail, and pinpointing its orbit for future flyby calculations. A movie from JPL explains: Asteroids this big have passed by Earth at similar distances many times before, but this is the first time astronomers have known about the flyby in advance. For instance, a similar encounter occurred in 1976 when 2010 XC15 split the distance between Earth and the Moon. Researchers didn't discover that space rock until 24 years after the flyby. The Nov. 8, 2011, passage of 2005 YU55 thus represents a rare opportunity for asteroid research. Experienced amateur astronomers should be able to photograph 2005 YU55 as it zips through the constellations Aquila and Pegasus glowing like an 11th magnitude star. Even under the full moonlight of Nov. 8th, such a bright asteroid is within reach of mid-sized backyard telescopes. The timing of the flyby favors observers in western Europe and eastern parts of North America. Check Sky & Telescope for observing tips or go straight to JPL for the object's ephemeris. NORTHERN LIGHTS: Last night, auroras danced around the Arctic Circle. "The Moon was strong, but the Northern Lights were even stronger," reports Joseph Bradley who sends this picture from Whitehorse, Yukon: The source of the display was a turning of the interplanetary magnetic field (IMF). The IMF tipped south for a while, partially cancelling Earth's north-pointing magnetic field. Solar wind entered the breach and fueled the auroras. "The auroras were great in Greenland, too," adds National Science Foundation researcher Ed Stockard who witnessed auroras at dawn from the International Science Support Facility in Kangerlussuaq, Greenland. October 2011 Aurora Gallery [previous Octobers: 2010, 2009, 2008, 2007, 2006, 2004, 2003, 2002] 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 November 8, 2011 there were 1256 potentially hazardous asteroids. Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Mag. | Size | 2011 FZ2 | Nov 7 | 75.9 LD | -- | 1.6 km | 2005 YU55 | Nov 8 | 0.8 LD | 11.2 | 400 m | 2011 UT91 | Nov 15 | 9.9 LD | -- | 109 m | 1994 CK1 | Nov 16 | 68.8 LD | -- | 1.5 km | 1996 FG3 | Nov 23 | 39.5 LD | -- | 1.1 km | 2003 WM7 | Dec 9 | 47.6 LD | -- | 1.6 km | 1999 XP35 | Dec 20 | 77.5 LD | -- | 1.0 km | 2000 YA | Dec 26 | 2.9 LD | -- | 80 m | 2011 SL102 | Dec 28 | 75.9 LD | -- | 1.1 km | 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 | |