Post
by alter-ego » Mon Mar 30, 2015 4:45 am
Chris Peterson wrote:Ludo wrote:Thanks Geck for the swift reply. I've seen those but I sort of expected more from different angles given their large field of view.
Their field isn't as large as you might think. The horizon is only a couple thousand kilometers away, and you can only see reasonable detail for probably six or seven hundred kilometers. They could easily have missed the eclipse completely.
Yes, throughout the entire 4-picture sequence (From ISS and the transit), the umbra was not yet visible. However, if the ISS ran 15 minutes later, it would crossed the terminator right on the edge of the emerging umbra. I made a composite in Google Earth showing the ISS orbital positions for each of the four pictures. Even on the 2nd pass, ISS totally missed the penumbra. Commenting on the Earth picture taken at 9:01, the umbra would not have been visible for about another 10 minutes. The visible shadow must be some shadow gradient nearing inner penumbral edge.
Google Earth, ISS Orbit and Solar Eclipse.JPG
Nitpicker wrote:Guest wrote:I'm having a difficult time proving this alignment happened. Where was ISS Mar 20 2015 9:20 UT?
The ISS is directly above the Earth (and the Sun and the Moon) at all times.
According to Mr Legault's page (available from the APOD caption) --
http://www.astrophoto.fr/eclipse-iss-20150320.html -- the transit happened at 09:05:04 UT. The timing can be quite sensitive to observation location on Earth (and also the ISS boost schedule, see:
https://www.heavens-above.com/IssHeight.aspx).
I found the timing of 9:05:04 is indeed duplicated by Stellarium when the correct TLE set (and maybe Stellarium version?) is used.
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Last edited by alter-ego on Tue Mar 31, 2015 3:30 am, edited 1 time in total.
A pessimist is nothing more than an experienced optimist