Wednesday night offers Vineyarders a lunar eclipse perfectly timed for observing. The full moon rises in the eastern sky just as the sun sets at about 5:04 p.m. and the best part of the show is five hours later.

One can only hope that the weather cooperates as the next time the Vineyard will have so convenient a show will be in December 2010.

This February full moon is called the Snow Moon, which is located in the zodiacal constellation Leo and in close proximity to the bright ringed-planet Saturn.

The evening starts out with a brilliant moon rising over the Atlantic Ocean.

Shortly after 8 p.m., the moon enters the Earth’s shadow, known as the penumbra.

Don’t expect to see anything significant until 8:43 p.m. when the moon enters the darkest part of the Earth’s shadow, known as the umbra.

From then on, a curtain appears to move across the moon’s face.

Total eclipse begins at 10 p.m. when the moon is fully covered by the Earth’s umbra. Mid-eclipse is at 10:26 p.m.

Though the moon will be fully covered by the Earth’s shadow from 10 p.m. to 10:52 p.m., notice that the southern part of the moon appears slightly brighter than the rest of the moon, as the moon drifts close to the southern edge of the umbra.

The moon starts to come out of the umbra at 10:52, and comes completely out after midnight, at 12:09 a.m.

The Earth’s atmosphere is responsible for the moon’s glow at the peak of the eclipse.

Lunar eclipses can vary in brightness based on how many clouds are in that narrow ring of light.