patrickfwd@yahoo wrote: << I've got a few questions about ISS brightness. First of all, by what factor was the mag decreased by the recent 25 mile increase in its distance from the earth? Also, how much will the mag increase when the new Zvezda module is attached? >> Each magnitude corresponds to a factor of about 2.5 in actual luminosity (5 magnitudes is defined to be a factor exactly 100 and 2.51... is the fifth root of 100). The addition of Zvezda will roughly double the size of ISS and so its luminosity should be about double under most lighting conditions. Expect magnitudes about 0.75 brighter than at present. When completed, ISS should be about 2 magnitudes brighter than at present. Changes in luminosity due to distance are governed by the inverse-square law. If ISS is twice as far away from you on one pass than on another, its luminosity is reduced by a factor of four. Since a 25 mile increase in orbital distance is only a small percentage change, this will not lead to a significant change in brightness of ISS --only about 0.2 magnitudes for passes which are otherwise identical. -Frank E. Reed Chicago, IL ----------------------------------------------------------------- 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 : Fri Jun 02 2000 - 17:35:37 PDT