At 23:56 17/07/00 , Mark Harris wrote: > >Does a decay differ much from a meteor? > >Time: 00.02 GMT >Direction: looking South-West >Altitude: about 25 degrees Yes it does Mark. Decaying satellites are essentially in circular orbits at heights around 100Km. This means there speed is that of such an orbit, about 8.3Km/second. Meteors must have at least escape velocity ( 11.2 Km/second) and most have speeds above 20Km/second right up to the maximum 73 km/sec. The relatively slow speed and horizontal direction of velocity for a satellite decay mean that you should see it for quite some time, say 30-40 seconds at moderate elevations, and may be over a minute if you can see objects low on your horizon. So the object you saw HAD to be a meteor, purely on the basis of the duration. Since meteoroids follow power law distribution [ 10 times more massive are 100 times less frequent], Sighting a bright meteor is a rare occurence. I have only ever seen one meteor approaching the brightest Iridium flares observed. Tony Beresford Adelaide, So <aust ( 34.96s,138.63E) ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Mon Jul 17 2000 - 19:59:31 PDT