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Astronomical Sketching – Education in action — 2 Comments

  1. Very nice sketches. A question — in the left-most sketch you do not shade in the leftmost edge (the dark edge) of the moon as much as in the other two. I am wondering if you are seeing a lighter color there? Similar to this reported by Carlos Hernandez on ‘Astronomy Sketch of the Day’?


    I was struck by the Waxing Crescent Moon (2.4 days old) over the western horizon (~11 degrees) tonight (January 11, 2008 at 00:00 U.T.) as it appeared that the Earthshine over the unilluminated portion was asymmetric. I turned my 11 x 56 Oberwerk binoculars upon it and noted a brightening over the Moon’s northern (upper) limb. My wife also noted the brightening without my suggestion. There also appeared to be a “glow” surrounding the crescent Moon. I have never observed this over the Moon at this or any other phase. This most likey represnts an atmospheric phenomena (e.g. haze or diffuse cloud).


    I ask because I have found reference to this in the work of a 17th-century astronomer who also sketched it.

    • In this sequences of lunar sketches the progression of the phase is toward full left to right. The left sketch on December 6th is showing the moon at almost first quarter . The terminator is not straight it has a curve on it so the moon is 5 days since new. There may be some faint Earthshine present in this waxing gibbous phase that offers a slightly brighter lunar surface. In the right hand sketch on December 12th the moon is almost full , at 11 days since new. The dark limb most likely looked that way to me because most of the lunar surface at that point is drenched in sunlight . Your two day observed waxing crescent would be lit by direct sunlight. The two day old crescent moon would look glowing for that reason . Almost the opposite of my third sketch in the sequence. During the waxing phases Earthshine decreases as sunlight increases. Not sure if that answers your question.
      Best regards

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