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Total Eclipse of the Moon – Sunday evening, September 27
Residents of Ivins and surrounding communities – and the en-tire United States – will be treated to a total eclipse of the moon on the evening of Sunday, September 27. The St. George Astronomy Group and Ivins City will offer free public viewing with telescopes at Unity Park in Ivins. This is the last total eclipse of the moon visible from Utah for almost 2½ years.
An eclipse of the moon happens when the moon moves into the shadow of the earth and grows dark. This can happen only at full moon, when the moon is opposite the sun in the sky. Usually the moon’s orbit takes the moon above or below the earth’s shadow and in most months there is no eclipse, but if the alignment is just right the moon can move into and through the shad-ow, and for an hour or so the moon grows dark as sunlight is blocked by the earth.
The visible phase of the eclipse begins at 7:07 p.m. MDT when the moon begins to move into the inner (umbral) part of the earth’s shadow – but as seen from Ivins the moon does not rise until at least 7:19 p.m.! This rising time is calculated for a perfectly flat horizon and in reality it will be at least several minutes and likely much longer before the moon rises above hills to your east and actually becomes visible to you. The time that you will first see the moon depends on the height of hills and mountains to your east, so for best viewing find a place with a low eastern horizon (or be prepared to wait until the moon rises from your location).
At moonrise the moon has moved only a short distance into the earth’s shadow and the moon’s left edge is noticeably darker than the rest. During the next hour the moon moves deeper into the earth’s shadow and the shadow creeps across the moon’s face, moving from left to right. At 8:11 p.m. the moon moves fully into the earth’s shadow and totality begins. At that moment the moon is a scant 9 degrees above the true horizon.
The eclipse is total from 8:11 p.m. until 9:23 p.m. with mid-eclipse at 8:47. When totality ends at 9:23 the moon is 23 degrees high (1/4 of the way up the sky) and a bit south of due east. The eclipse is partial for the next hour as the moon slowly moves out of the earth’s shadow, and the eclipse ends at 10:27 p.m.
Assuming that the moon is above your local horizon, the best time to look is around 9 p.m. when the moon is deep in the earth’s shadow.
The St. George Astronomy Group (SGAG) will set up telescopes for free public viewing of the eclipse at Unity Park in Ivins on 400 South midway between 200 West and 400 West. Parking is available on 400 South and in the parking lot one block to the east. Viewing begins at moonrise shortly after 7:30 p.m.