Re: strange question on geo sat passing into the moon's shadow

From: Björn Gimle (b_gimle@algonet.se)
Date: Mon Nov 01 2004 - 16:16:16 EST

  • Next message: Tony Beresford: "Re: Flying blankets?"

    Not so strange - an interesting mathematical problem.
    The solution is quite easy using rectangular geocentric coordinates from the
    JPL Horizons' site (or computed from other sources)
    
    I made an Excel spreadsheet to convert these values into the center of the
    shadow cones, when crossing the equatorial plane, and plotting these tracks
    as they cross the Clarke belt, computing the intersections.
    
    You don't have to wait to 2015, when the New Moon occurs on declination 0.
    In fact, you missed an opportunity on Oct. 14 2004 at 09:38 UTC, 177.5
    degrees E
    The next one is Nov. 12 at 16:29, but 103.5 E would be out of your range.
    
    In fact, it appears that favourable eclipses for some parts of the world
    occur 1-3 times each time the New Moon is slightly further from the equator
    than the Sun is.
    
    I will post additional facts and graphs, and the spreadsheet, within a day
    or two to DSat, which allows attachments.
    
    SkyMap will show you when satellites pass through lunar umbra (not
    penumbra?) if you select that on the F7/L menu. This is quite easy for LEO
    near the time of a solar eclipse, even far from you. For geo's the
    computation above helps a lot to determine when and where to look. I have
    produced an example for 2004-11-12 at 16:29 UTC from equator at 103.5 E,
    near RA 3h decl.+0, which you could reproduce yourself (even before I send a
    SkyMap.cfg attachment)
    
    /Björn
    
    ----- Original Message ----- 
    
    > I was fooling around again.
    >
    > On Mar 20, 2015 the moon and sun will be in a good spot, to allow the
    moon's shadow to block part
    > of the sun's light as seen from the geo sat belt.
    >
    
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