This single, four hour long exposure from the evening of January 20/2000 shows a full Moon trailing through hazy skies above Phoenix, Arizona, US. Of course, the picture also shows something else -- a total lunar eclipse.
A lunar eclipse is caused when the full moon enters Earth's shadow and as the eclipsed Moon's light grows steadily fainter, the Moon trail becomes narrow and dim. The total eclipse phase, when the Moon passes completely within Earth's shadow, occurs near the middle of this Moon trail arc.
But even during totality, the Moon trail is visible and noticeably red. Normally illuminated by sunlight which falls directly on its surface, during a total lunar eclipse the Moon is still illuminated by sunlight filtered and refracted through Earth's atmosphere. The refracted light lends the eclipsed Moon a dim and reddish appearance.
Image and info via APOD
Image credit & copyright: Joe Orman
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