Amateur astronomers observe asteroids as they impact Jupiter

WASHINGTON - Armed with video cameras, amateur astronomers may provide much-required data on the number of large asteroids slamming into planets like Jupiter, and help improve estimates of the danger near-Earth asteroids pose for our planet.

Astronomers have reported follow-up observations of a June 3, 2010, asteroid impact on Jupiter first noticed by two amateur astronomers.

“These amateur astronomers-Christopher Go in the Philippines and Anthony Wesley in Australia saw a flash of light lasting about two seconds, which is the first time such a small object has been observed impacting Jupiter,” said co-author Imke de Pater, professor and chair of the Department of Astronomy at the University of California, Berkeley.

“I bet that if we looked at other data amateurs have, we would see many more events like that.”

The team of professional astronomers subsequently observed the impact region through the Hubble Space Telescope and the Keck telescope in Hawaii.

Since the ApJ paper was submitted, two amateur astronomers in Japan — Masayaki Tachikawa and Aoki Kazuo — observed another asteroid collision with Jupiter on Aug. 20.

“Both of these bolides were 10-meter objects, leaving trails for less than two seconds,” de Pater said, too small and too brief to be observed by professional astronomers except by chance. These amateurs, however, were able to record for long periods of time using color video cameras, which is ideal for capturing transient events such as impacts.

De Pater and some of the same co-authors have had a paper accepted by the journal Icarus analyzing another Jupiter impact discovered by Wesley on July 19, 2009.

That impact, de Pater said, involved an asteroid entering Jupiter’s atmosphere along a shallow angle and exploding just below Jupiter’s cloud layers.

The most famous impact discovery by an amateur was Comet Shoemaker-Levy 9, which crashed into Jupiter in 1994, creating a scar visible for weeks.

According to the authors of the ApJ paper, the June 3 asteroid was 8-13 meters in diameter and packed a punch equivalent to a 250- to 1,000-kiloton nuclear bomb-smaller than the violent airburst that decimated trees for 40 kilometers around Tunguska in central Siberia 100 years ago, but similar in its effects.

These initial observations, if supplemented by future observations of asteroid impacts on Jupiter by other amateur astronomers, could help scientists understand the behavior of meteoroids of various dimensions and composition entering an atmosphere at varying angles and speeds, said co-author Mark Boslough of Sandia National Laboratories.

“These amateur observations are very important,” he said. “To me, the primary significance is the demonstration that relatively small bolides on Jupiter can directly be observed from Earth, that their energy can be quantified and that such impacts are frequent enough to observe.”

A continuous amateur observation campaign could provide data to determine the impact intensity and size of asteroids in the vicinity of Jupiter.

The paper has been accepted for publication in Astrophysical Journal Letters. (ANI)