Deep Impact space collision reveals comets to be fluffy balls of powder

The Guardian ^ | 9/7/2005 | Ian Sample, science correspondent

[R. Scott]

If comets are so loose why would we need to divert one from a collision course with Earth?

A mass of a few million tons is still a few million tons – regardless of density.

[Junior]

This one has potential.

[Junior]

Some believe this evidence will hold true for all comets..

The Leonid meteor swarm is supposed to be the rocky debris left by a comet. One gets the impression "comet" might be a catch-all term for "objects composed mostly or entirely of gaseous material in highly elliptical orbits."

[ZinGirl]

If comets are so loose why would we need to divert one from a collision course with Earth?

EPA regulations, probably. Clean Air Act, etc....can't have all those airborne particulates...it's against the law. (smirk)

[LRS]

[PatrickHenry]

This one has potential.

I donno. We've had threads before about organic material in space. Lemme mull this one over.

[Swordmaker]

Temperature differential?

What is the volatile material? Dust does not act like a gas... I suggest electricity.

[gogogodzilla]

Comets... The intergalactic dust bunny.

And coming soon, the intergalactic version of the dreaded BROOM!!!

:-)

[biggerten]

Basic physics.

Force = Mass x Acceleration.

Fluffiness doesn't enter the equation at all.

Either way, BLAMM!

[mdmathis6]

If they are that loosely packed, then a few nukes fired into them should creat a shock wave with all the melting water and methane going up all at once and blowing them apart.

I can't believe all comets are made this way.

[raybbr]

Asteroids and meteroids are a different breed.

Just what are "meteroids", pray tell?

[Cincinatus]

An asteroid (i.e., a solid particle, usually very small) that is entering the Earth's atmosphere, leaving an visual ionization trail. In space, just before entry, it is a meteoroid; after it's landed on earth, it's a meteorite.

[Jack of all Trades]

The other 20% to 25%..

It's a small mass, but mass, nonetheless

Yes, but the mass is fixed, and was known beforehand wasn't it? I would think the mass can be determined from observations of the orbital path. The size of the comet is known, so there was an expectation of the object's density. The article indicates that the Deep Impact results show the density is 20 to 25% of the expected value. That doesn't seem to add up.

[raybbr]

I know a meteoroid is but what is a "meteroid". :}

[Cincinatus]

A small meter?

[R. Scott]

What is the volatile material? Dust does not act like a gas... I suggest electricity.

It could be electromagnetic – but I can’t visualize the process that would cause material to bleed off from sunlight exposure solely from the electric charge. Even in the far reaches of space sunlight will heat material. Wouldn’t a spot that is slightly warmer then be less dense than its surroundings – and break free from gravitational and electromagnetic forces that hold it in place? There is also the matter of light pressure (think solar sail) brought up earlier.

[cogitator]

NASA's Deep Impact Adds Color to Unfolding Comet Picture

One of the scientists studying the comet is named Jessica Sunshine. No kidding.

[r9etb]

The premise of this article is deeply flawed -- they're saying that because this comet appears to be a "fluffy ball of powder," then all comets must be fluffy balls of powder.

Color me highly skeptical.

[Doctor Stochastic]

...size of a football pitch ...

I'm guessing this means the size of a soccer field.

[r9etb]

That's Jessica on the right. I think....