Comments on: Asteroid Imposters

By: Aodhhan

Aodhhan — Fri, 05 Sep 2008 11:53:38 +0000

I totally understand your frustration with the IAU. Unfortunately, we really do need this organization (well… one which provides their function). I just wished they operated a bit friendlier.
I don't think I'm the only one who believes they come off a bit eliteist, staunchy, pompus, arrogant, condescending, narrow minded, narcissistic, bone-headed, stubborn, irritating etc.

By: Todd

Todd — Thu, 04 Sep 2008 22:53:45 +0000

I'm with Jorge.

Human beings often feel secure classifying an object as one thing or another.

In reality comets and asteroids are the same type of body, differentiated only because of how they differ as seen from the Earth.

Modern genetics has linked animals more accurately than gross morphology.

I think it's inevitable that small solar system bodies will be scientifically classified on a system that includes specific gravity (rubble pile, solid, or in between) and geochemical composition (ices, metals, silicates, or some combination). From the surface of planet Earth (or some other body) lay people will long refer to comets, asteroids, and meteor showers. Scientists now describe them more accurately.

By: Jorge

Jorge — Thu, 04 Sep 2008 22:11:28 +0000

Wanna bet that that's precisely why this question of nomenclature will end up surfacing sooner or later? The complexity, I mean.

Then, we'll see some (myself included) wanting to set one umbrella category for all the smallish things going around stars (or not… we'll see) and subdivide from there, and others just stating that old categories just became "meaningless" and so on and so forth…

If only the IAU stayed out of it, it might even be constructive, interesting and educational. But the IAU will not stay out of it, so it'll be a noisy mess, filled with silly definitions nobody agrees with. You'll see.

By: Aodhhan

Aodhhan — Thu, 04 Sep 2008 18:28:10 +0000

Jorge…
Unfortunately the world doesn't support your point. As humans we tend to classify everything into as many different areas as possible.

Relatively speaking, we are still pretty ignorant on the composition of both asteroids and comets. Its likely, as we become smarter on these celestial bodies, we will find there are not only many different types of asteroids, comets etc, but many different stages, periods of evolution and ways they are created.

In short, it is only going to get worse!

…nothing is ever so bad, that it cannot get worse.

By: Jorge

Jorge — Thu, 04 Sep 2008 16:25:10 +0000

Sure. But then what's the point of trying to differentiate a "dying comet that has lost most of the volatile materials that create their characteristic tails" from an "asteroid proper", if they are basically the same thing?

(I don't even like the term "volatile materials", btw: all materials are volatile, in the proper temperature range, which is basically the point I'm trying to make here)

By: neoguru

neoguru — Thu, 04 Sep 2008 14:34:18 +0000

Words, words, words. A comet by any other name is still a comet, etc. What'cha call 'em is irrelevant. It's what they ARE that counts and I believe it important that we differentiate beween the types and call 'em whatever applies.

By: watchful stone guardian

watchful stone guardian — Thu, 04 Sep 2008 14:26:21 +0000

How about "cometoids"?

By: Gerald, Walnut Creek, CA

Gerald, Walnut Creek, CA — Wed, 03 Sep 2008 22:48:05 +0000

Perhaps an appropriate name for asteroids that are really dormant comets would be: "dwarf asteroids." Or maybe: "dwarf comets." How about "cometinos" or "asterinos?" I think the IAU needs to get on this right away.

By: Jorge

Jorge — Wed, 03 Sep 2008 21:56:09 +0000

I increasingly dislike the separation between comets and asteroids in small body taxonomy. What's the difference between a "dying comet that has lost most of the volatile materials that create their characteristic tails" and, say, a rubble pile asteroid? For all practical purposes, there is none. It's just an asteroid by another name, especially if it lost them a long time ago. And a comet with all the volatiles intact that never wonders into the inner system is also simply an asteroid by another name. Judging by the ice-rich outer system moons, they are likely visually and structurally very similar to ice-poor asteroids and their properties are probably pretty much the same, with rock-hard ices working mostly just as rock-hard… er… rocks do in inner system asteroids. Only if and when they get kicked inwards they start to erupt and really become comets.

Besides, a "common" asteroid that wonders close enough to a star also begins to erupt, comet-like. Iron, for instance, boils at 3000 K, and you get much higher temperatures than that in star coronae. Why isn't it called a comet, then?

This is another astronomical designation that comes from the times of old and seems to me to be losing grip on reality as the knowledge improves, becoming in increasingly dire ned of redefinition.

I'd go for scrapping it alltogether. Instead I'd prefer talking about objects that exhibit cometary behavior. At most, I'd designate by "comet" the objects that exhibit periodic cometary behavior (since it does change their surfaces and probably their internal structure). Everything else would simply be asteroids, regardless of their composition.