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31 Dec 2018

Shadow Stories: Everything You Need to Know About the Total Eclipse of the Moon on Sunday, Jan. 20

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6:37 p.m. PST on Sunday, Jan. 20: The moon enters penumbra. The edge of the penumbral shadow will not be noticed, but the moon may seem especially bright then, because the moon most strongly reflects light back toward the source—the sun (and Earth, when the moon is just outside the Earth’s shadow). Look up opposition effect.

7:34 p.m.: Moon enters umbra. The moon begins to enter the dark central core of the Earth’s shadow. How long before this will you first notice the inner penumbral darkening on the moon’s east-southeast edge? How many minutes after first umbral contact will you notice the circular edge of the Earth’s shadow? When will you first notice any color within the shadow?

8:41 p.m.: Total eclipse begins. A few minutes before this time, the almost totally eclipsed moon, with a northwest-north-northwest narrow edge still in sunlight, is likely to be strikingly beautiful. Within the shadow, watch for reddish colors on the moon from sunlight which has passed through the Earth’s atmosphere and been refracted onto the moon. Use the 5-point Danjon scale and select the L number from 0 to 4, which best fits the description of the brightness and color of the moon in total eclipse. Use your own words to describe the eclipse! Repeat at greatest eclipse, and again at the end of totality. If you’re in a dark place during totality, enjoy views of the stars in the absence of bright moonlight. Look for the Beehive star cluster 6 degrees east of the moon.

9:12 p.m.: Greatest eclipse. The moon is closest to the center of the Earth’s shadow. Can you detect any color? Again, use the Danjon scale. Normally, we expect the eclipsed moon to appear darkest around this time. Note the “Twins” Pollux and Castor, 10-15 degrees to the upper left of the moon, and the “Little Dog” star Procyon, 17 degrees to the moon’s lower right.

9:43 p.m.: Total eclipse ends. Again, use the Danjon scale and your own words to describe the eclipse. Now, a few minutes after this time, when a narrow edge of direct sunlight illuminates the northeast edge of the moon, the nearly totally eclipsed moon is likely to be very beautiful.

10:51 p.m.: Moon leaves umbra, or dark central core of Earth’s shadow. How long after this time can you still notice any penumbral shading on the moon’s west-west-southwest edge?

11:48 p.m.: Moon leaves penumbra. You will not notice darkening near this time, but it is around this time we can expect the moon, just outside Earth’s shadow, to shine with extra brilliance. Adding to this opposition effect, the moon at perigee during this eclipse and the Earth-moon system being just a few weeks past perihelion (closest to Sun) combine to further increase the moon’s brightening.

• After January 20, 2019, the next total lunar eclipse visible in parts of U.S. will be on the morning of Wednesday, May 26, 2021; the total phase will be seen from all locations west of a line from east Texas/western Louisiana to eastern Montana. From California, the moon begins to enter umbra, or the dark central core of Earth’s shadow, at 2:45 a.m., followed by a brief, 15-minute totality from 4:11 a.m. until 4:26 a.m. The moon will then be low in the southwest, and morning twilight will be getting under way. The northern edge of the moon will be just barely within the umbra and should be noticeably brighter than the rest of the totally eclipsed moon. The star Beta in the head of Scorpius will be only two degrees north of the moon during totality. From the Coachella Valley, the moon will set a few minutes before completely exiting the umbra, but most of the California coast will be able to see the fully sunlit lunar disk for a few minutes after it departs from the umbra at 5:52 a.m.

• A very deep partial lunar eclipse (magnitude 97.4 percent) will be seen throughout the U.S. on the night of Nov. 18-19, 2021. From Western states, the moon enters the umbra at 11:19 p.m. on Thursday, Nov. 18. Greatest eclipse occurs at 1:03 a.m. early on Friday morning, Nov. 19. A very narrow brightly sunlit southern edge of the moon remains outside the umbra at greatest eclipse, while the rest of the disk shows dark grey or rusty brown hues. It should be a beautiful sight! At deepest eclipse, the Pleiades star cluster will be within 6 degrees north of the moon. The moon moves completely out of the umbra at 2:47 a.m.

• A deep total lunar eclipse will be seen from the contiguous 48 states on the night of May 15-16, 2022. Some western states will miss the start of the initial umbral phase, and northwest Washington state misses the start of totality. From Palm Springs and the Coachella Valley, the moon hasn’t risen yet when it begins to enter the umbra on Sunday, May 15 at 7:28 p.m. The eclipse is total for 85 minutes beginning at 8:29 p.m., during evening twilight. At deepest eclipse at 9:11-9:12 p.m., the northern part of the totally eclipsed moon should appear very dark as it passes through the center of the Earth’s shadow. As totality ends at 9:54 p.m., the moon is 11 degrees east of Alpha Librae and 7 degrees west of Beta Scorpii. Note the reddish (eclipse-colored?) star Antares, heart of the Scorpion, 14 degrees to the lower left of the moon. The concluding partial eclipse ends as the moon completely leaves the umbra at 10:55 p.m.

• A deep total eclipse on morning of Tuesday, Nov. 8, 2022 will be seen throughout U.S. For parts of the East Coast, the moon sets near the end of total eclipse. From California, the moon enters the umbra at 1:09 a.m. A long 85-minute totality, second of the year, occurs from 2:17 a.m. until 3:42 a.m. At deepest eclipse, at 2:59 a.m., the southern part of the moon should appear very dark as it passes through the center of Earth’s shadow. At the same time, Uranus, of magnitude 5.7, is easily seen in binoculars only 1.7 degrees to the upper left of the reddened moon; a telescope will reveal the planet’s greenish disk. The concluding partial eclipse ends at 4:49 a.m. as the moon completely leaves the umbra.

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