Will a crescent be visible on the night on the same day that the solar eclipse (annular) was observed?

Any solar eclipse would be good information ... but I want to know particularly about annular. Crescent as in a very thin very vey fine line of the moon. I need to know visibility in terms of naked eye.


Thanks for th information .... So I guess for annular it would be more difficult to see the crescent the same night.

I want annular becuase the date I am working on was an annular eclipse. I'm trying to find the first sighting of moon after that eclipse.

2 Answers

  • 1 decade ago
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    Probably not with the naked eye. According to Sky & Telescope magazine, the youngest crescent Moon to be observed was 11 hours 40 minutes after New Moon (visible with optical aid) and 15h 32m with the naked eye: http://www.skyandtelescope.com/observing/objects/p...

    So it might be possible to observe an eclipse first thing in the morning and see the crescent Moon in the evening. In the Sky & Telescope article, there are a number of requirements mentioned. Two of these would not be fulfilled. One is that the Moon should pass at its maximum 5º above or below the Sun at New Moon, in order to maximise the elongation angle. This is obviously not the case at an eclipse.

    Another requirement is that the Moon be close to perigee, where its hourly motion is greater, thus causing it to move away from the Sun more rapidly. At an annular eclipse (why specify annular anyway?) the Moon is nearer apogee than perigee and moving more slowly.

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  • Annular eclipses occur (as do total eclipses and partial eclipses of the Sun) when the Moon is new. In the case of annular eclipses, if the Moon is at apogee (furthest distance from Earth in its elliptical orbit) its angular size is small enough to not fully cover the Sun's disk. The Earth may also be at perihelion (closest distance from the Sun) which may add to the lack of coverage.

    Spotting a crescent moon after new usually isn't easy under two days or so. Some have spotted and taken pictures of a crescent moon about 18-20 hours after the new phase (i.e. conjunction with the Sun). They were spotted under very good seeing conditions and sky transparency.

    DO NOT try to spot the young crescent moon that early using binoculars or telescope --- unless the Sun was hidden behind a structure/building. The consequences of the Sun entering the field of binoculars or telescope would be instant permanent blindness. Not worth the challenge of "spotting" the young moon.

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