Comet LINEAR did not become a spectacular naked-eye object as many stargazers had hoped, but it is intriguing astronomers with its peculiar dynamic behavior.

Dashing the hopes of many sky watchers around the world, comet C/1999 S4 (LINEAR) was too faint to see with the unaided eye as it made its closest approach to Earth on July 22nd. Its visual magnitude appears to have peaked between magnitude +6.0 and +6.5, just below the threshold for naked-eye observations. Nevertheless, the comet is still a good target for binoculars or small telescopes.

LINEAR may have disappointed casual stargazers, but it is intriguing professional astronomers with unpredictable behavior including jets that are perturbing the comet's orbit and an outburst in July that may have sent a fragment hurtling away from the comet's core.

Comet LINEAR surprised astronomers using the Hubble Space Telescope (HST) with a brief, violent outburst on July 5, 2000. The comet's brightness soared by a factor of 1.5 during a four hour period. Two days later astronomers spotted at least one house-sized fragment trailing the nucleus by more than 450 km.

"We lucked out completely," said Hubble comet-watcher Harold Weaver of the Johns Hopkins University, Baltimore, MD in a press release. "In one surge of brilliance this under-performing comet showed us what it could have been. Comet LINEAR generally has not been as bright as we had hoped, but occasionally does something exciting."

"The July 5th flare was probably associated with the separation of the fragment," says Brian Marsden of the Minor Planet Center at Harvard University. "Fragmentation releases fresh icy material and exposes it to solar radiation, causing the comet momentarily to brighten."

If such a flare had occurred this week as LINEAR was approaching the Sun (it was closest to the Sun on July 26th) the comet might have become visible without a telescope.

Something similar happened to the already-brilliant comet C/1996 B2 (Hyakutake) in 1996. Ground based telescopes recorded transitory flares while the Hubble Space Telescope and others captured pictures of fragments flying away from the nucleus.

Full Story: http://spacescience.com/headlines/y2000/ast28jul_1m.htm?list

Mitch Battros
Producer - Earth Changes TV
http://www.earthchangesTV.com