At least a strong shower

Meteor showers occur whenever we ride into the dusty debris left behind in a comet's orbit. The debris left behind by Kiess, a comet last seen in 1911, is what produces the Aurigids. The comet takes approximately 2,500 years to orbit the Sun, but there are also dense trails of dust traveling along its orbit. Earth has had glancing blows in the past with a few of these dust trails in 1935, 1986 and 1994.

In 2007, however, the Earth is expected to pass very close to the center of a dust trail, which astronomers Esko Lyytinen of Finland and Peter Jenniskens of NASA's SETI Institute in California said, should result in "a spectacularly rich shower of bright meteors."

The researchers in the past used computer models to predict outbursts of the Leonid meteor shower, which wowed skywatchers in 2001 and 2002.

Shooting stars, or meteors, are common any night of the year; five or six per hour are normal. During a respectable meteor shower, they can be seen streaking across the sky every few minutes. But occasionally the sky explodes in a shower of sparks, a rare meteor "storm" that is something to get excited about.

Meteor storm possible?

No one is certain how strong next year's Aurigids may be, but tomorrow, Jenniskens will make an announcement at the General Assembly of the International Astronomical Union in Prague concerning an "Aurigid Meteor Storm" of Sept. 1, 2007.

Meteor storms are typically said to involve at least 1,000 meteors per hour, a rate sometimes achieved only in 15-minute bursts. It is not clear what sort of hourly rate Jenniskens will announce as his prediction, however.

"I do not know why Peter Jenniskens will announce this as a storm," Lyytinen told SPACE.com. "I have not especially tried to predict the strength but I would guess only a good or moderate shower, a storm not impossible."

The peak of the shower is predicted to occur at 11:37 GMT. Unfortunately this comes during daylight for Europe and much of North America. But the western United States and Canada, as well as much of Alaska and Hawaii will still be in pre-dawn darkness and would be in an excellent position to view it.

Another drawback will be a gibbous Moon, four days past full, whose light could interfere with observing. But, Lytinnen said, many of the meteors are expected to be very bright. "So, maybe the moon does not make very much harm in the observations ... I hope."

"The goal is to discover these killer asteroids before they discover us," said Nick Kaiser of the University of Hawaii's Institute for Astronomy, which hopes to train four powerful digital cameras on the heavens to watch for would-be intruders.

There are no asteroid busters to stop one right now, but scientists believe that one day a defense could be devised, such as using spacecraft to divert a killer comet.

Congress has asked
NASA for a plan to comb the cosmos for even smaller, more distant objects, including asteroids just 1 1/2 football fields across. The space agency is to catalog their position, speed and course by 2020. Already, there are 103 objects on an "impact risk" watch list.

Scientists warn there are as many as 100,000 of these "smaller" heavenly bodies with the potential to take out entire cities or set off a tsunami like the killer wave that swept through the Indian Ocean in December 2004.

Earth's craters bear silent witness to what can happen even when a smallish asteroid slams home. In 1908, one struck remote central Siberia, unleashing as much energy as a 15-megaton nuclear bomb. Fortunately, it wiped out 60 million trees, not people. Had it hit a populated area, the loss of life would have been staggering.

There's some recent good news too: Earth's most pressing threat - the asteroid 99942 Apophis - appears to have eased. Scientists initially gave it a 1-in-5,500 chance of hitting the planet in 2036, with enough power to wipe out the New York City metro area. But experts said Thursday the latest observations suggest those odds have dwindled to 1-in-30,000.

They won't be sure until it makes an earlier pass in 2029, when it's expected to come within 18,640 miles of Earth. If that sounds comfortably distant, consider this: It's closer than many commercial satellites and a good deal nearer than the moon.

Although close encounters are unnerving, they give astronomers a unique opportunity to get a better glimpse of asteroids and comets - the leftover building materials of the universe - and gain a better understanding of the origins of the solar system.

Scientists say expanding their database of the objects crowding Earth's neighborhood could help produce a permanent warning system like those that now monitor the Pacific for tsunamis or keep tabs on volcanoes and earthquake zones.

Give the world a decade or so of lead time to deal with a specific threat, they say, and it stands a chance of getting out of harm's way - perhaps by sending up a spacecraft to nudge an asteroid off-course.

"Right now, unfortunately, there are no 'asteroid busters' or hot lines. Who ya gonna call?" said Andrea Milani Comparetti, a professor of mathematics at Italy's University of Pisa.

To be on the safe side, astronomers trying to determine the odds of one hitting Earth work with computer models that surround it with thousands of "virtual asteroids." Experts then map out the likely orbits for each one and factor those in to come up with the probability of an impact.

But widening the search for threatening objects creates a problem: Discoveries could become commonplace, either creating unnecessary panic and confusion or lulling the public into a false sense of complacency.

"We're now going to be finding such objects once a week instead of once a year," said David Morrison, a NASA scientist who will chair the new task force.

"Only in Hollywood do asteroids arbitrarily change orbits," he said. "But there is great potential for misunderstanding. Dealing with probability and risk is a problem for all of us, whether we're dealing with asteroid impacts or terrorist attacks."

Bottom line: Mankind may not be able to dodge every cosmic bullet.

"It's through collisions that planets are born," said Giovanni Valsecchi of Italy's National Institute of Astrophysics. "And it's through collisions that planets die."

Nakano, reading from notes from another Civil Defense official, said it was seen at 10:18 a.m. headed away from the airport.

But an eyewitness, who asked that his name not be used, told the Star-Bulletin he saw it heading from the Civic Auditorium area to the Keaukaha area, which would take it over the main runway.

That witness saw a silver tube with no markings or fins, trailing "vapor" that quickly dispersed.

"The noise was super-loud," he said.

Police also interviewed about a half-dozen witnesses who saw or heard it, said police spokeswoman Chris Loos.

Loos and the nameless witness said there were plane flights before and after the object was sighted, but the object did not appear connected to their presence.

At Pohakuloa Training Area, 30 miles to the west, spokesman Bob McElroy said there were no military exercises using missiles.