Earth shine
September 22nd 2010 05:43
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When the new crescent moon is a few days “old” you may have noticed a smoky glow on the dark portion of the Moon. The smoky “glow” is referred to as earthshine (not moonshine).
Earthshine is caused by sunlight reflected of the earth’s surface and the moon appears to bathed in a dull light. We see part of the Moon as a crescent
illuminated by the Sun and the rest of the Moon dimly illuminated by this doubly reflected light from the earth we call earthshine.
Earthshine can be seen just after sunset, the same thing occurs to the “old” crescent moon in early morning just before dawn.
Because the moon does not have its own light the reflectivity of the moon its "albedo" is less than that of the Earth, which makes earthshine appear dimmer.
The term albedo is when an object is measured by how strongly it reflects light from a light sources such as the Sun.
We only see earthshine during the crescent phases of the Moon because during these phases only a small portion of the Moon is illuminated, just after new moon and after the moon has waned.
On October the 5th 2010 observers in both hemispheres will be able to seen earthshine just before dawn around 5:00 am Southern hemispheres look towards the west and look east for Northern hemisphere observers.
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