"Thierry" . wrote in message ...
Hi,

Have you recently checked all the litterature speaking about the speed at
which Huygens plunged into Titan atmosphere.
Don't have you noted what I call another "mistake of style"... ?
In fact we all know that on earth the sound speed is about 331 m/s at 0°C
(or in imperial units 742 mi/h at 32F)

On Titan, mostly filled with nitrogen ( 80%) at -200°C, the sound speed is
only 174 m/s. Mach 1 is thus reached at 627.6 km/h instead of 1194 km/h like
on earth.

I think Mach 1 is defined as the sound of speed at sea level at 0 deg C. Implicitly we mean "on
earth".
Mach 1 is therefore an absolute number, and the same everywhere in the universe.
--
md
10" LX200GPS-SMT
ETX105
www.xs4all.nl/~martlian