Mohawk Valley Astronomical Society

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Shadow Our Moon

by Perry Pezzolanella

Shadow our Moon with Earth shadows. There are three types of lunar eclipses, and no two eclipses are exactly alike. A lunar eclipse occurs when the Earth aligns between the Sun and Moon. The Earth can cast a shadow onto the Moon, but we do not live in a perfect universe. If we did, there would be total lunar eclipses every month. The Moon does not orbit the Earth along the equator but is inclined 5º to the ecliptic. This means that the perfect moment of the Sun, Earth, and Moon aligning only happens twice a year just short of six months apart.

A total lunar eclipse is where the dark shadow of the Earth, called the umbra, completely covers the Moon. If the Moon is unusually far from Earth, totality can last as long as 107 minutes. Most total lunar eclipses last from 30 to 75 minutes. Another type of eclipse is a partial lunar eclipse. The Sun, Earth, and Moon line-up is not perfect, so the Moon passes only through the edge of the dark shadow. How deep and what part of the shadow the Moon crosses can make for interesting partial eclipses with only a dark notch taken out or almost all the Moon eclipsed. The Man in the Moon during partial eclipses can have its chin, mouth, forehead, one eye, or both eyes “bitten off” for an interesting if not amusing sight. The third type of eclipse is a penumbral eclipse. The Moon does not enter the dark shadow (umbra) but comes close. The result is a very subtle shading of the portion of the Moon that is closest to the umbra. From the surface of the Moon the Sun would appear only partially eclipsed as the Earth would block only part of the Sun.

The most interesting aspect of a total lunar eclipse is the color. The classic color is copper, but once again this is not a perfect universe, therefore colors will vary among eclipses. The coppery or reddish color is due to the sunlight passing through the Earth’s atmosphere at a shallow angle like sunrises and sunsets on Earth. The color of the eclipse is simply the color of sunrises and sunsets that ring the Earth as seen from the Moon. The Earth would be a dark disk blocking the Sun surrounded by a coppery ring of sunlight. If the Earth’s atmosphere is unusually cloudy or dusty; the lunar eclipse will appear darker and bloody red or bronze. If there was a large volcanic eruption, the Earth’s atmosphere would be full of ash and block a lot of sunlight. The result would be a nearly black lunar eclipse and the Moon would nearly disappear during totality like it did on December 9, 1992, after the 1991 Mount Pinatubo eruption. If the atmosphere is unusually clear and clean, the result is a bright eclipse with a lot of gold and even some blue fringing, such as was the total lunar eclipse of January 20-21, 2019.

The most enjoyable aspect of any lunar eclipse is that they are safe to look at and totality evolves slowly over time compared to the swiftness of total and annular solar eclipses. Even the weather can be forgiving during the longer total lunar eclipses as some of it might be visible between clouds or if it clears up fast enough. The best thing is that no travel is required to see lunar eclipses as anyone on the night side of Earth can see it, weather permitting, and if it is cloudy, another total lunar eclipse is usually no more than seven years away with a bonus that they often come in pairs or triplets (2 or 3 in a row within 12-18 months). Here are the the circumstances for each total and partial lunar eclipse through 2035:

September 17, 2024 – A partial lunar eclipse is visible during the convenient evening hours with 9% of the northern portion of the Moon eclipsed at 10:44 P.M. The partial phase begins at 10:12 P.M. and ends at 11:17 P.M.

March 14, 2025 – A beautiful total lunar eclipse that is worth waking up early to observe as it will last 76 minutes. Totality begins at 2:26 A.M., mid-totality is at 2:59 A.M., and totality ends at 3:32 A.M. The Moon will pass through the southern portion of the umbra, so look for a darker forehead. The partial phase begins at 1:09 A.M. and ends at 4:48 A.M. Do not miss this one and hope for clear weather even if it is cold, because it will be over four years until the next one, and that one will be awesome!

August 27-28, 2026 – This is an almost total lunar eclipse with the Moon 93% eclipsed at 12:13 A.M. and it is a long one for a partial event. The eclipse begins at 10:33 P.M. and ends at 1:52 AM. Look for a bright forehead as this will be the only part of the Moon not eclipsed.

January 11, 2028 – This is a minor partial lunar eclipse with only 7% of the southern portion of the Moon eclipsed at 11:13 P.M. The partial phase begins at 10:44 P.M. and ends at 11:42 P.M.

June 25-26, 2029 – Mark your calendars for the biggest, longest, and best total lunar eclipse in decades, rivaling the long one of July 5-6, 1982, as totality will last an incredible 103 minutes, almost the longest possible! The Moon will pass dead center through the umbra and will be near its closest point to Earth, perfect for a long total lunar eclipse. Even better is that it occurs early with the partial phase beginning at 9:32 P.M. and totality starting at 10:30 P.M. Mid-totality is at 11:22 P.M. and could be a deep bloody red enhanced by the fact that the Full Moon is always low all night nearest the summer solstice and in the thicker atmosphere closer to the horizon. Totality ends at 12:13 A.M. and the partial phase ends at 1:13 A.M. Do not miss this one and the weather should be warm with a better than 50% chance for a clear night.

December 20, 2029 – The second of a pair of total lunar eclipses will be a dinnertime special and noticeably shorter than its pair in June lasting 55 minutes, barely half as long. The Moon rises in the northeast already partially eclipsed, and totality begins at 5:14 P.M. and ends at 6:09 P.M. with mid-totality at 5:42 P.M. The northern portion of the Moon will be the darkest. The partial phase ends at 7:29 P.M.

October 8, 2033 – Get up early for this total lunar eclipse and watch it set in the west as twilight brightens. The partial phase begins at 5:13 A.M. with totality starting at 6:15 A.M. Mid-totality is at 6:55 A.M. as the Moon sets and sunrise ending the last total lunar eclipse visible here until February 11, 2036.

September 27, 2034 – This eclipse will be interesting for how little of the Moon will be eclipsed and it will be a quick one! Only 2% of the northern edge will be eclipsed at 10:46 P.M. It starts at 10:33 PM and ends less than a half hour later at 11:00 P.M.

August 18, 2035 – This is another minor partial evening lunar eclipse. Around 11% of the southern portion of the Moon will be eclipsed at 9:11 P.M. The eclipse begins at 8:32 P.M. and ends at 9:49 P.M.

There will be many total and partial lunar eclipses beyond 2035 and there are many penumbral lunar eclipses not mentioned here for the curious observers. Lunar eclipses are fun, educational, and safe. Be sure to take the time to observe them as this is a great way to introduce children to the wonders of our universe.