[meteorite-list] Amateur Astronomers Are First To Detect Objects Impacting Jupiter

[Ron Baalke]

Sep. 9, 2010

Dwayne Brown 
Headquarters, Washington      
202-358-1726 
dwayne.c.brown at nasa.gov 

Jia-Rui Cook 
Jet Propulsion Laboratory, Pasadena, Calif. 
818-354-0850 
jia-rui.c.cook at jpl.nasa.gov 

RELEASE: 10-217

AMATEUR ASTRONOMERS ARE FIRST TO DETECT OBJECTS IMPACTING JUPITER

WASHINGTON -- Amateur astronomers using backyard telescopes were the 
first to detect two small objects that burned up in Jupiter's 
atmosphere on June 3 and Aug. 20. 

Professional astronomers at NASA and other institutions followed up on 
the discovery and gathered detailed information on the objects, which 
produced bright spots on Jupiter. The object that caused the June 3 
fireball was estimated to be 30 to 40 feet in diameter - comparable 
in size to asteroid 2010 RF12 that flew by Earth on Sept. 8. 

The June 3 fireball released five to 10 times less energy than the 
1908 Tunguska meteoroid, which exploded 4-6 miles above Earth's 
surface with a powerful burst that knocked down millions of trees in 
a remote part of Russia. Scientists continue to analyze the Aug. 20 
fireball, but think it was comparable to the June 3 object. 

"Jupiter is a big gravitational vacuum cleaner," said Glenn Orton, an 
astronomer at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, 
Calif., and co-author of a paper that will appear online Thursday in 
Astrophysical Journal Letters. "It is clear now that relatively small 
objects that are remnants from the formation of the solar system 4.5 
billion years ago still hit Jupiter frequently. Scientists are trying 
to figure out just how frequently." 

The lead author of the paper in Astrophysical Journal Letters is 
Ricardo Hueso of the Universidad del Pais Vasco in Bilbao, Spain. 

Before amateurs spotted the June 3 impact, scientists were unaware 
collisions that small could be observed. Anthony Wesley, an amateur 
astronomer from Australia who discovered a dark spot on Jupiter in 
July 2009, was the first to see the tiny flash on June 3. Amateur 
astronomers had trained their backyard telescopes on Jupiter that day 
because the planet was in a particularly good position for viewing. 
Wesley was watching real-time video from his telescope when he saw a 
2.5-second-long flash of light near the edge of the planet. 

"It was clear to me straight away it had to be an event on Jupiter," 
Wesley said. 

Another amateur astronomer, Christopher Go, of Cebu, Philippines, 
confirmed the flash also appeared in his recordings. Professional 
astronomers, alerted by email, looked for signs of the impact in 
images from larger telescopes, including NASA's Hubble Space 
Telescope, the European Southern Observatory's Very Large Telescope 
in Chile, and Gemini Observatory telescopes in Hawaii and Chile. 
Scientists saw no thermal disruptions or typical chemical signatures 
of debris, which allowed them to put a limit on the size of the 
object. 

Based on the data, the astronomers deduced the flash came from an 
object - probably a small comet or asteroid - burning up in Jupiter's 
atmosphere. The object likely had a mass of about 1-4 million pounds, 
about 100,000 times lighter than another object that hit Jupiter in 
July 2009. 

The second fireball on Aug. 20 was first detected by Japanese amateur 
astronomer Masayuki Tachikawa. It flashed for about 1.5 seconds and 
left no debris observable by a large telescope. 

"It is interesting to note that while Earth gets smacked by a 
10-meter-sized object about every 10 years on average, it looks as 
though Jupiter gets hit with the same-sized object a few times each 
month," said Don Yeomans, manager of the Near-Earth Object Program 
Office at JPL. "The Jupiter impact rate is still being refined and 
studies like this one help to do just that." 

Previous models of collisions this size on Jupiter had predicted as 
few as one and as many as 100 such collisions a year. Scientists now 
believe the frequency must be closer to the high end of the scale. 

To see images and videos of the two impacts, visit: 

http://www.nasa.gov/topics/solarsystem/features/jupiter20100909.html 
	
-end-