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(meteorobs) Excerpt from "CCNet LETTERS TO THE MODERATOR, 16 March 2000"
------- Forwarded Message
From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
To: cambridge-conference@livjm.acdot uk
Subject: LETTERS TO THE MODERATOR, 16 March 2000
Date: Thu, 16 Mar 2000 16:11:35 -0500 (EST)
LETTERS TO THE MODERATOR, 16 March 2000
---------------------------------------
[...]
(3) FASTEST SPINNING ASTEROID?
Petr Pravec <ppravec@asudot cas.cz>
[...]
===================
(3) FASTEST SPINNING ASTEROID?
>From Petr Pravec <ppravec@asudot cas.cz>
Charles F. Peterson <cfp@mcn.org> wrote:
> In terms of useful information about NEAs, it would seem that the
> velocity of the surface of the asteroid tells more than the rotational
> period. Am I correct?
> The surface of a 100 meter asteroid with a rotational (day/night)
> period of 10 minutes is not moving as fast at its equator as the
> surface of a one kilometer asteroid with a much longer rotational
> period. Surface velocity would tell something about origin and impact
> history, right? Day/night period seems to be an interesting but
> inconsequential artifact of the relationship of diameter to surface
> speed.
Actually, the most important information brought by the detection
of a fast asteroid spin is the ratio between centrifugal
acceleration and gravitational acceleration on the asteroid's
surface. The superfast spins tell us that the asteroids are
rotating under tension and therefore are monolithic. (I.e., not
gravitationally bound "strengthless" bodies.) The information
about asteroids internal structure is one of the main reasons why
to study asteroids spins. The fast day/night changes are less
important scientifically (but interesting for general public to
remember, thus they were pointed out in the press release so
widely distributed), but they are still relevant e.g. for
computation of temperature distribution on the asteroid surface.
Petr Pravec
-----------------
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