(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 it’s 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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