Those Worrisome Comets

I am fascinated by the astrophysics programs on The History Channel. But after watching them ad nauseam a couple of things aren't making sense to me. Comets for one.

Garden variety comets seem to be made primarily of dust and ice. As the comet streaks along, the dust and ice are blown off into space creating the comet's tail. It occurred to me that after a while the comet would wear away or melt away into nothingness. That's logical, isn't it? An ice cube eventually melts away into nothingness. If a comet is made of ice, shouldn't it do the same?

Maybe I wasn't fully comprehending the size and magnitude of comets. Maybe they are extra huge, some size beyond my human bean comprehension. So I Googled and Wikied. I picked Halley's Comet to work on because even the cool kids have heard of it.

From Wikipedia:

"Halley's nucleus is relatively small (barely 15 kilometers long, 8 kilometers wide and 8 kilometers thick.) As it approaches the inner Solar System, the Sun warms it, causing its surface to sublimate (change directly from a solid to a gas), and jets of volatile material to burst from its black surface. The gases ejected from the nucleus are 80% water vapor, 17% carbon monoxide and 3% carbon dioxide with traces of hydrocarbons. When Halley's comet is closest to the Sun, temperatures can rise to about 77 °C. Near the Sun, several tons of gas and dust are emitted each second in the jets."

OK then. Let's apply a little arithmetic to this thought process. All this math is approximate since astrophysicist types seem to qualify all statements with "approximately."

Halley's Comet is approximately 960 cubic kilometers (15 x 8 x 8) or 960,000,000,000 cubic meters. That's approximately twice the size of Manhattan. That's one big ice cube people. And Wiki says it is relatively small. Pft. Compared to what????

A metric ton of water is equal to one cubic meter of water, or approximately the size of the ordinary cookstove. That's not the big honkin' 8-burner Vikings by the way, just the regular ol' 4-burner Magic Chefs.

There are 864,000 seconds in a day.

I'm arbitrarily deciding that "several" as in "several tons per second" is equal to 3.

Halley's Comet would be spewing out 2,592,000 cubic meters (864,000 sec. x 3 metric tons/cubic meters) of shtuff per day. Visualize it pooping out 2.6 million cookstoves per day into outer space.

That's a lot of shtuff.

If I've done all my math correctly, Halley's Comet should melt itself away in 370,370 days, or 1,015 years....if it spews shtuff continuously.

If it only spews when "near the sun", then that's a whole new batch of calculations. If "near the sun" is the time period during which the comet is visible on Earth (4 months or 120 days), then that baby should last another 231,450 years, (370,370/120 = 3086 orbits x every 75 years = 231,450) or until the year...oh hell, I won't be around then.

All that leads to new questions. Was Halley's Comet larger back in 240 BC when first spotted? Or does it accumulate new ice and dust bits as it orbits out to the far reaches of our solar system?

These are the things I ponder in the wee small hours of midnight.

Dang, where is Neil deGrasse Tyson when ya need him?????

Neil, call me.