(meteorobs) Hypervelocity meteors
meteoreye at comcast.net
meteoreye at comcast.net
Tue Dec 11 12:16:54 EST 2007
No it can't.
If it is approaching the earth from behind at 0 km/s (OK, well 1 mm per millenia :-> ), once it enters the earth's gravitational field, by the time it hits the atmmosphere, it will be travelling 11 km/sec. (actually 11.2 km/sec IIRC). That is the earth's escape velocity.
If it enters the gravitational field with a nonzero velocity, it will be going faster, but that's the lower limit.
Wayne
-------------- Original message --------------
From: Karl Antier <ka.antier at wanadoo.fr>
> Hi George, hi all,
>
> Just a small question about geocentric meteor velocities that I never manage
> to fix... As the question is raised...
> You say :
> > What this boils down to is that the slowest geocentric velocity a meteor can
> > have while in a solar orbit is 11 km/s (7 mps). Visually a meteor at this
> speed
> > looks as if itâs crawling along.
> Why isn't the slowest meteor velocity in a geocentric coordinate system 0 km/s ?
> I imagine 11 km/s has something to due with terrestrial escape speed, but why
> couldn't
> a meteor have a smaller speed in geocentric coordinates ?
> Imagine a meteor following the Earth. It would have 0km/ relative speed.
> Make it go faster, it'll enter the Earth atmosphere with a slightly bigger
> speed, but
> which could be under 11 km/s. Couldn't it ?
>
> Thank you in advance for your answers !
> Clear skies to all for the Geminid display !
> Karl
>
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