From: "Tom Wagner" <sciteach@mchsi.com> > > In my thinking---and this is not a mathematical analysis for sure and may be > totally wrong :~) but, if the observer was looking toward the low earth > orbit (LEO) satellite that was about to enter the moon's shadow the observer > would have to be relatively close to the line of sight of the sun/moon. That > would make it so the sunlight would be on the far side of the satellite > which would make it a silhouette (thereby invisible). Well actually, at an altitude of 250 miles, the ISS sees the horizon about 1500 miles away (and so it's about 1500 miles away, when you observe it rising above your horizon). The moon has a radius of about 1000 miles, so there's 500 miles where the space station would neither be especially in the direction of the sun (and hence would have plenty of light reflecting off it), nor in any part of the moon's shadow. Owing to the fact that the sun is not a point source of light- but like the moon is about 1/2 degree in angular size- the moon's shadow on the earth (like an airplane passing overhead at low altitude) is fuzzy, and the area of total darkness (i.e., the umbra) is relatively small. So in reality, during an eclipse transit, you'd see the brightness of the space station begin to diminish as it entered the shadow, drop to nothing when it crossed the face of the moon (that is, while in the umbra), and then increase in brightness as it emerged from the umbra. ----------------------------------------------------------------- To unsubscribe from SeeSat-L, send a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@satobs.org List archived at http://www.satobs.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Sat Mar 01 2003 - 17:26:04 EST