If you are tired of thinking about global warming, terrorist attacks or contracting a deadly new virus, maybe you could get out of your rut by mulling over the possibility that some large celestial body may be on a collision course with our planet.

Last month, the asteroid 2004 XP14 passed some 268,873 miles (432,000 kilometers) from Earth. That distance is slightly greater than that between the Earth and the moon.

Astronomers called it "a close shave in the vastness of outer space."

If a collision had occurred, the memory of the Fourth of July fireworks would be dimmed. Pig Out in the Park would have to be canceled for a couple thousand years.

Scientists say that a fatal cosmic concussion probably will come from a giant chunk of rock like 2004 XP14 - one of the many that jump from the asteroid belt under the evil influence of Jupiter - or a comet returning to our solar system. That comet would show up as a stationary but growing dot of light in the night sky.

It would appear stationary because it would be coming straight at us.

Although total planetary destruction is still total planetary destruction, death by comet might be preferable to death by meteor.

The first advantage of a comet impact is that astronomers would be able to give us more time to prepare for extinction. You would not have time to read a thick novel, go on a diet, work a 12-step program or even play an extended game of Monopoly, but you would have time for a frank no-holds-barred talk with your in-laws or to unload some bottled-up grievances to your boss.

A comet also would provide several days of spectacular visual effects with its fluffy ice and vapors streaming behind.

On the other hand, a typical giant meteor would provide nothing to look at until it flamed up for a few scant seconds prior to the explosion that would wipe us all out.

Another reason that we earthlings might prefer oblivion by comet is that the meteor strike has been done before.

Scientists say that dust from a meteor hit filled the air back in 65 million B.C. Most life on Earth was wiped out.

Scientists know this because buried in the Earth at the 65 million year depth is a layer of iridium, a nonbiodegradable element that is relatively rare on Earth but a common component of meteors.

Dinosaur fossils are found below that iridium layer while mammal bones are found above. If we take another big hit, our only comfort is that a life form higher than humans may evolve above our own bones.

Then, like the dinosaurs, we'll be gone but not forgotten forever; after a few million years our successors (the new life forms) will dig up our bones and display them standing naked in their museums with a sign that says, "They didn't know what hit them."

There probably will be scary movies made about us, and they are sure to make disparaging remarks about our tiny brains.

If you want to be "in-the-know" before the Earth is obliterated, go to the Spokane Astronomical Society's Web site, spokaneastronomical.org. The group has lots of free information, and it holds "star parties" where members provide powerful telescopes, free to the public, so you might get a look at the celestial threats that currently are heading our way.

Just don't tell me about it.