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Comet Pan-STARRS a dud, should we bother with ISON?

By Marshall Connolly, Catholic Online (NEWS CONSORTIUM)
March 18th, 2013
Catholic Online (www.catholic.org)

Sky watchers hopeful for a glimpse of Comet Pan-STARRS have been heartily disappointed, this author included. Failing to meet naked-eye expectations, except from sites with the darkest possible skies, the comet has been labeled a dud by many observers. So, with Comet ISON due up next, what justifies all the hype?

LOS ANGELES, CA (Catholic Online) - As Comet Pan-STARRS heads back out into space, growing fainter and harder to detect by the day, Comet ISON is on its way in. ISON is predicted to be the main event of the astronomical year and has been labeled the "comet of the century" despite the fact it is still yet to pass by Earth.

Why all the fuss?

Comet ISON is a new comet, a first-time visitor to the solar system which means it is pristine. It hasn't ever experienced heating and sublimation, that is melting of its surface layers. That means astronomers can examine its dust to determine its primordial composition. This will tell us more about how our solar system formed.

Still, this alone does not seem to justify the excitement. Comet ISON may fizzle out, or even break up as it approaches the Sun. We could be denied any show at all. Despite this fact, NASA and other agencies are marshalling a tremendous number of resources to view the comet.

Karl Battams, a scientist at the U.S. Naval Research Lab in Washington told Space.com, "Observing campaigns are planned by the SOHO, STEREO and SDO solar missions; by Spitzer, Chandra and Hubble space telescopes; and by the Deep Impact, JUNO, Mercury MESSENGER, Mars Odyssey and Mars Reconnaisance Orbiter missions. Other missions at or on Mars are looking into observing ISON, as are a handful of other NASA Planetary missions."

This may just be the tip of the iceberg. A number of other international agencies undoubtedly have their observing campaigns planned, as well as millions of amateur astronomers who are prepared to view and photograph the comet as it passes through the inner solar system.

Even casual spectators may be in on the fun as Comet ISON is expected to be so bright in the sky, that it may rival the full moon in brightness for several days following its closest approach to the sun. That could make the comet visible in daylight.

The reason why such an outlay of capital and enthusiasm is occurring is because this is an exceedingly rare event. Decades, or even centuries may pass between such bright comets. The science that can be gleaned from their passage is great, revealing much about the primordial composition of the solar system, since comets are leftovers from the creation of the sun and planets.

Although ISON could fizzle out, break up, or otherwise disappoint, it is too great a chance for astronomers to let it go without making a maximum observing effort.

Comet ISON has a lot going for it, in terms of putting on a good show. The comet is large, at least two kilometers in size, and this is its first pass by the sun, meaning it has plenty of accumulated ice and dust to give off. That will make it appear bright.

Comet ISON is also expected to pass just 680,000 miles from the surface of the sun, which is practically touching in astronomical terms. This will heat the comet so much so that it will cast off much more material than most. Its large size however, means it should survive the close pass without breaking up.

The result is an exceptionally bright comet, that will shed much more dust and gas than normal. This means easier observing and a good look at the pristine, primordial dust that makes the comet's tail.

So what about you, the casual stargazer who has little interest in astronomy, should you be excited? Of course! Comet ISON is very likely to be a dazzling sight in the evening skies beginning in late November and through December. It will be perhaps the only time you will see such an object. Even if just for novelty's sake, it's worth keeping one eye on the heavens this fall.

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