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Ephemeris: 09/17/2024 – Super Harvest Moon Eclipse tonight

September 17, 2024 Comments off

Note: the eclipse isn’t that super, however tonight’s full moon is a supermoon, and the Harvest Moon to boot. On with the program.

This is Ephemeris for Tuesday, September 17th. Today the Sun will be up for 12 hours and 23 minutes, setting at 7:48, and it will rise tomorrow at 7:25. The Moon, at full today, will rise at 7:47 this evening.

Tonight’s full Harvest Moon* is also a supermoon and on top of that it will be partially eclipsed in Earth’s shadow. The Moon will just clip the bottom or south part of the Earth’s inner shadow called the umbra between 10:13 PM and 11:15 PM. Only 8% of the Moon’s diameter will be covered by the umbra at maximum eclipse at 10:44 PM. However, the Moon will spend a fair amount of time in the Earth’s penumbra, the outer part of the shadow, where the Sun is only partially blocked. So the moon will appear dimmer than normal at its upper parts from about 9:45 to 11:45 PM or so. Viewing the moon through a pair of sunglasses will enhance the effects of the dimming of the penumbra, cutting down the Moon’s glare.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.

* The Harvest Moon is the full moon nearest the date of the autumnal equinox which this year is on the 22nd of September. What makes the Harvest Moon special is the Harvest Moon Effect. Check it out this previous post where I explained more about it: Here

Addendum

A preview of the Moon in five stages before during and after the eclipse
Here we have a preview of the Moon in five stages before during and after the eclipse. In time we’re moving from right to left just as the Moon moves against the background of the sky and the Earth’s shadow. Of course during all this period of time the Earth’s rotation is moving the sky in the opposite direction much faster. Be that as it may, before the Moon enters the Earth’s penumbra it is evenly eliminated by the Sun. At 10:18 PM the Moon has been immersed 5 minutes into the umbra so it’s taking a little bite out of its upper left part. The effect of the Moon being deeply immersed in the penumbra is also visible. Mid eclipse is at 10:44 PM. At 11:10 PM the Moon is 5 minutes before leaving the umbra. By 12:48 AM the Moon has cleared the penumbra and is again fully illuminated. Click or tap on the image to enlarge it. The Moon images were created using Stellarium, assembled using GIMP and annotated using LibreOffice Draw.
Categories: Astronomical Event, Ephemeris Program, Observing Tags: , , ,