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    Re: Longitude by Sunset
    From: h.a.c. van Asten
    Date: 2012 May 7, 12:30 -0700

    You can observe the far away Venus on the horizon when setting , but not the nearby moon (see earlier comment) since the latter´s horizontal parallax is larger then the refraction at low elevation of body . As a result nobody has ever seen actual moonrise /-set : the refraction uplifts the image with a positive amount of arcminutes which is trespassed by a negative amount of arcmin due to parallax , the latter being larger . So if true moon´s centre is in your horizon , you can not see it since its image is below your horizon . When downing the visual moon fades like the sun does , with the remark that the sun is a light emitting body and the moon is a light reflecting one . At full moon as seen from earth , the sun is on the other side of the ecliptica : when your sun downs and your moon is still visible , it receives gradually less sunlight in the penombra , showing fainter & fainter
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