Re: Satellites passing through lunar penumbra/umbra

From: Thomas Fly (
Date: Mon Mar 03 2003 - 00:15:58 EST

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    From: "Dale Ireland" <>
    "In my experiences at 6 total eclipses I can't remember seeing any stars and
    only the brightest planets. probably nothing fainter than 0 or -1."
    The last time I saw the space station- which was longer after sunset than
    I'd have liked- it was headed in the direction of Jupiter, and was at least
    as bright as Jupiter before it went into the earth's shadow.  On at least
    one occasion, I've seen it significantly brighter than that (under the right
    conditions, supposedly it can reach -4).
    "I have wondered if it might be possible to get a photograph of a
    geosynchronous satellite passing through the lunar umbra or penumbra when
    the shadow may not necessarily strike the earth but only pass close to the
    earth. A time exposure tracking on the stars would show the satellite as a
    streak that would dim and brighten again."
    There are a lot of candidates in geosynchronous orbit, of course: so probably
    you'd get quite a few streaks (and maybe pick up a GPS satellite too, if you
    were lucky).  It's an interesting idea, but offhand, I'm not sure how common
    it is for the moon's shadow to fall within the circle of geosynchronous
    satellites.  You'd need .1 radian or less of separation between the moon and
    the sun (geosynchronous orbit / moon distance), which may be close to the
    present separation, in fact:
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