Space Weather News

 Space Weather News for Oct. 28, 2009
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INDONESIAN ASTEROID:  Earlier this month, with no warning, a ~10-meter wide asteroid hit Earth's atmosphere above Indonesia and exploded. The break-up was so powerful, it triggered nuclear test ban sensors thousands of kilometers away. A just-released analysis of infrasound data shows that the asteroid detonated with an energy equivalent of  about 50 kton of TNT, similar to a small atomic bomb.  This significant impact has received relatively little attention in Western press.  Details are available today on http://spaceweather.com.

SUNSPOT UPDATE:  Since it emerged last weekend, new-cycle sunspot 1029 has become the biggest and most active sunspot of 2009.  It is crackling with B- and C-class solar flares and putting on a good show for amateur astronomers. This one sunspot does not put an end to solar minimum, but it is a remarkable break from the calm.  Check htttp://spaceweather.com for images and updates.

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BIG SUNSPOT: The sun is showing signs of life. Sunspot 1029 emerged over the weekend, and it is crackling with B- and C-class solar flares.  The active region's magnetic polarity identifies it as a member of new Solar Cycle 24. If its growth continues apace, sunspot 1029 could soon become the biggest sunspot of 2009.  Check http://spaceweather.com for animations and updates.

MONDAY NIGHT SKY SHOW: When the sun sets on Monday, Oct. 26th, go outside and look south. Jupiter and the Moon are converging for a beautiful conjunction. The bright pair can been seen even through thinly-clouded skies and city lights. Don't miss it!

CONNECT YOUR PHONE TO THE SKY:  Would you like a call when Earth-orbiting satellites detect strong solar flares and solar wind gusts?  Sign up for Spaceweather PHONE to turn your telephone into a bona fide solar activity alert system: http://spaceweatherphone.com

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New subscribers: To sign up for free space weather alerts, click here: http://spaceweather.com/services/ . To unsubscribe click here: http://www.spaceweather2.com/u?id=1346058X&n=T&l=spaceweather or send a blank email to leave-spaceweather-1346058X@www.spaceweather2.com

METEOR SHOWER UPDATE: The Orionid meteor shower is subsiding, but it's not done yet. International observers are still reporting as many as 25 Orionids per hour as Earth exits the debris stream of Halley's Comet. Readers, if you are up before dawn, keep an eye on the sky for last-minute Orionids. [sky map] [gallery]

GEOMAGNETIC ACTIVITY: High-latitude sky watchers should be alert for Northern Lights. A sharp gust of solar wind hit Earth on Oct. 21st, and the Arctic Circle is still ringing with geomagnetic activity. "[We had a] stunning display of active auroras last night," reports Thomas Hagen, who sends this picture from Tromsø, Norway

The solar wind gust that sparked the display is interesting because it likely originated with a spotless explosion in the Sun's southern hemisphere on Oct. 17th: movie. The blast hurled a faint coronal mass ejection (CME) toward Earth. Normally, CMEs reach Earth in only 2 or 3 days, but this one took a leisurely 4 days to cross the Sun-Earth divide. Why so long? Since solar minimum began in ~2007, solar physicists have noticed that CMEs have been moving in slow motion. They take a long time to get here, and they don't hit very hard when they arrive. Nevertheless, this one managed to spark some nice auroras. Browse the gallery for more.

Near-Earth Asteroids  
 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 October 23, 2009 there were 1076 potentially hazardous asteroids.
 

Oct. 2009 Earth-asteroid encounters: Asteroid Date(UT) Miss Distance Mag. Size
2001 CV26  Oct. 8  9.8 LD 13 2.2 km
2009 TJ Oct. 13  10.8 LD 18 130 m
2009 TM8 Oct. 17 0.9 LD 17 10 m
2009 TF8 Oct. 17 7.6 LD 19 20 m
2009 TH8 Oct. 19 4.5 LD 18 45 m
2009 UE  Oct. 19 2.5 LD 19 40 m
2009 UD Oct. 20 2.0 LD 17 17 m
1999 AP10  Oct. 20 29.7 LD 13 2.7 km
2009 TO8 Oct. 21 7.4 LD 19 27 m
2009 UJ Oct. 22 6.8 LD 19 25 m

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.