cometary

Fainter asteroids have been seen undergoing cometary outbursts (January issue, page 22), but if Scheila is a long-dormant comet, it's a big one.

"We were surprised to find such a late-forming, high-temperature little rock in these cometary samples," said Dr.

Star clusters and asterisms; double and newly emerging stars; planetary, cometary, emission, and dark nebulae--Orion has them all!

These analyses, the first that examined the hydrogen in water on bodies from a remote region, revealed a crucial chemical difference between the hydrogen in cometary ice and that in Earth's water.

Asteroids have been known to flare up with surprise cometary activity; four previous cases are on record.

This is the first time that astronomers have viewed a cometary breakup in such detail, notes Harold A.

"It's been half-way to Jupiter, executed picture-perfect flybys of an asteroid and a comet, collected cometary material for return to Earth, then headed back out into the void again, where we asked it to go head-to-head with a second comet nucleus," said Tim Larson, project manager for Stardust-NExT at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

In the next decade, infrared and microwave windows opened and mass spectrometers aboard spacecraft like Giotto allowed the nature of cometary dust to be determined.

"Furthermore, people have postulated--and it's just a hypothesis--that materials like this would have seeded the Earth from cometary tails that passed by the Earth early on after its formation," says Jewell.

If the activity in Scheila proves to be cometary in nature, this will be only the sixth known main-belt comet, and about 100 times larger than previously identified main belt comets," explained Larson.(ANI)

Now a research team finds that all the captured cometary grains formed near the Sun and somehow got transported to the outer solar system, where they mingled with the prevailing ices to create Comet Wild 2.

However, the ratio of deuterium to hydrogen in cometary water is much higher than in water on our planet.

The cometary debris ionised the atmospheric gas it passed through, boosting the current that normally flows between the ionosphere - an electrically charged region in the upper atmosphere - and the ground, according to him.

"They were one of three research teams who found the cometary material to have a geometric albedo of about six percent.

Another meteor storm, this one associated with a swath of cometary debris known as the Perseids, is credited with taking a satellite out of commission in 1993 (SN: 10/2/93, p.