Total Lunar Eclipse On Wednesday Will Be a Rare Selenelion By Joe Rao, Space Skywatching Columnist | October 05, 2014 08:17am ET 10.9K 337 43 Submit 774 Reddit First Total Lunar Eclipse of 2014 [Pin It] A photo of the first total lunar eclipse of 2014 taken from Arizona. Credit: Ron Delvaux via The Virtual Telescope Project View full size image Observers of Wednesday mornings total lunar eclipse might be able to catch sight of an extremely rare cosmic sight. On Oct. 8, Interested skywatchers should attempt to see the total eclipse of the moon and the rising sun simultaneously. The little-used name for this effect is called a selenelion, a phenomenon that celestial geometry says cannot happen. And indeed, during a lunar eclipse, the sun and moon are exactly 180 degrees apart in the sky. In a perfect alignment like this (called a syzygy), such an observation would seem impossible. But thanks to Earths atmosphere, the images of both the sun and moon are apparently lifted above the horizon by atmospheric refraction. This allows people on Earth to see the sun for several extra minutes before it actually has risen and the moon for several extra minutes after it has actually set. [How to See the Total Lunar Eclipse (Visibility Maps)] As a consequence of this atmospheric trick, for many localities east of the Mississippi River, watchers will have a chance to observe this unusual sight firsthand. Weather permitting, you could have a short window of roughly 2 to 9 minutes (depending on your location) with the possibility of simultaneously seeing the sun rising in the east while the eclipsed full moon is setting in the west. Regions of visibility From Newfoundland, the start of the partial stages of the total eclipse begins about 30 to 45 minutes before moonset. A growing scallop of darkness will appear on the upper left part of the moon when it sets as the sun is coming up. Across eastern Nova Scotia, only the lowermost portion of the moon will be in view as it drops below the western horizon. Farther to the west and south along the Atlantic seaboard, the moon will rise completely immersed in the Earths shadow. The map shows the visibility regions for the Oct. 8, 2014 total lunar eclipse, which is the second of four consecutive total eclipses of the moon between 2014 and 2015. Sky & Telescope Magazine released this viewing map. [Pin It] The map shows the visibility regions for the Oct. 8, 2014 total lunar eclipse, which is the second of four consecutive total eclipses of the moon between 2014 and 2015. Sky & Telescope Magazine released this viewing map. Credit: Sky & Telescope Magazine View full size image Now you see it … now you dont? Moon Globe 12 Moon Globe. Buy Here Credit: Space Store View full size image Then again, sighting a selenelion might be problematic feat. Twenty-five years ago, in the August 1989 issue of Sky & Telescope, Bradley Schaefer, an astronomer who extensively studied the visibility of the moon when it was low in the sky, noted that the full moon only becomes visible when it is about 2 degrees up and the sun is about 2 degrees below the horizon. So, depending on the clarity of your sky, you might have up to roughly 10 to 15 minutes before sunrise for the sky to still be dark enough, and the moon to be high enough above any horizon haze for it to be clearly visible. And keep in mind that this holds only for the uneclipsed portion of the moon. You might, however, be able to mitigate the effects of a brightening sky somewhat by using binoculars or a telescope. If the moon is totally eclipsed prior to sunrise, you probably are going to have to scan the western horizon with binoculars as the twilight brightens in order to still detect some semblance of the Moon, which will somewhat resemble a very dim and eerily illuminated mottled softball. End-Stages of Total Lunar Eclipse
Posted on: Tue, 07 Oct 2014 22:43:23 +0000
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