Blood moon lunar eclipse brings a rare ‘selenelion’ on November 8
Observers in the central and eastern United States and Canada should pay particular attention to the environment full moon on the morning of November 8, for that morning lunar eclipse will still be underway.
An interesting observation to try that morning would be to watch the eclipsed setting moon and rising sun at the same time. The little-used name for this effect is called a “selenelion,” a phenomenon that cannot happen according to celestial geometry.
And indeed, during a lunar eclipse, the sun and the moon are exactly 180 degrees apart in the sky; so in a perfect alignment like this (called a “syzygy”) such an observation seems impossible. But remember, thanks to our atmosphere, the images of both the sun and moon are seemingly “lifted” above the horizon by atmospheric refraction. This allows us to see the sun for a few more minutes before it actually rises and the moon for a few extra minutes after it’s actually set up.
Related: Beaver Blood Moon lunar eclipse 2022: everything you need to know
Joe Rao is a veteran meteorologist and eclipse hunter who also serves as an instructor and guest lecturer at the Hayden Planetarium in New York.
As a result of this atmospheric trick, for many places east of the Mississippi, there will be a chance to observe this unusual sight firsthand with the shadowy November event; a short window of about 4 to 9 minutes (depending on your location) where there is the opportunity to simultaneously see the sun rise in the east, while the eclipsed full moon sets in the west.
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From Newfoundland, the partial stages start about 80 minutes before moonset; a growing scallop will appear on the upper left portion of the moon as the dawn sky clears and the moon slides into total eclipse less than a quarter of an hour before setting. Likewise, the moon will set further west and south over Nova Scotia and along the immediate Atlantic coast, completely submerged in the Soil‘s shadow. See the table (below) for specific details for twenty selected locations in the US and Canada.
|Place||Time zone||sunrise||moonset||Moonset Mag*|
|St. John’s, NF||NST||6:55 am||6:59 am||Total|
|Halifax, NS||AST||7:02 am||7:06||Total|
|New York, NY||IS||6:35||6:41||Total|
|Charlotte, North Carolina||IS||6:51||6:58||0.75|
|Pittsburgh, Pennsylvania||IS||6:58||7:05 am||0.65|
|New Orleans, LA||CST||6:20||6:26||0.34|
|St. Louis, MO||CST||6:35||6:44||0.07|
*Moonset Mag: The fraction of the Moon’s diameter within the Earth’s shadow at the Moon’s setting, rounded to the nearest percent.
Now you see it. . . not now?
On the other hand, seeing a selenelion can be a problematic feat. Thirty-three years ago, Bradley Schaefer, an astronomer who has extensively studied the moon’s visibility low in the sky, noted in the August 1989 issue of the journal Sky & Telescope that the full moon doesn’t become visible until about 2 a.m. degrees up and the sun is about 2 degrees below the horizon.
So, depending on the clarity of your sky, you may have until about 10 to 15 minutes before sunrise before the sky is still dark enough and the moon high enough above any horizon nebula to be clearly visible. And remember that this only applies to the unclipped part of the moon. However, you can somewhat mitigate the effects of a glowing sky by using binoculars or a telescope.
If the moon is completely obscured before dawn, you’ll probably need to scan the western horizon with binoculars as dusk clears to still detect a gleam of the moon, which somewhat resembles a very dimly and eerily lit mottled softball.
A strange moonset
For those parts of the United States and Canada a few hundred miles inland from the East Coast, the moon’s rise from the umbra should be well seen a little later. The low partially eclipsed Moon in deep blue twilight should provide a wide variety of interesting scenic possibilities for artists and astrophotographers alike. From Buffalo and Pittsburgh and south through the eastern Ohio Valley and into the Piedmont to the Florida Panhandle, a curious-looking crescent moon with its cusps down will appear to set beyond the western horizon.
Farther west, across the central Great Lakes down through the deep south to the Gulf of Mexico, the moon on the lower right will appear nicked by the shadow.
If we go even further west, the moon will go “full” down, but diligent observers from much of Wisconsin, Iowa, western Missouri, eastern Oklahoma to central Texas can still spot a faint penumbral spot. detect the right lower limb of the moon when the western horizon is clear of nebula.
Joe Rao is an instructor and guest lecturer at New York’s Hayden Planetarium (opens in new tab). He writes about astronomy: Natural History Magazine (opens in new tab)the peasant almanac (opens in new tab) and other publications. follow us on twitter @Spacedotcom (opens in new tab) and further facebook (opens in new tab).
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