The week of November 7-13 takes us from Lunar Day 15 to Day 20. This week we will highlight the wrinkle ridge Dorsum Oppel on the moon and the lunar eclipse.

series of wrinkle ridges on the moon known as Dorsum OppelDorsum Oppel: [NE/H15; L=53°E] As the lava cooled following the impact that created Mare Crisium, a series of wrinkle ridges, known as Dorsum Oppel, formed on the moon along the entire western edge and give the impression of waves lapping on the shore. The flowing lava partially filled the pre-existing craters Yerkes and Lick [H15], turning them into ghost craters.

There is also a more substantial ridge that connects the flooded crater Yerkes with the smaller Yerkes E, 15 miles to its northwest (unnamed on the Field Map). Under a low Sun, when the terminator is around 52°-55°E, this ridge will combine with the SW rim of Yerkes to look remarkably like the silhouette of a bird in flight. It has consequently been nicknamed the Flying Eagle. (This feature may be seen to better advantage on Day 17 when the Sun is setting.)


On Tuesday, November 8, there will be a total lunar eclipse visible from the U.S. (beginning at 1:00 a.m. in Denver, reaching maximum at 4:00). On Wednesday, the Pleiades star cluster will be 3° north of the Moon.


It is highly recommended that you get a copy of Sky and Telescope’s Field Map of the Moon, the very finest Moon map available for use at the telescope. It is available for $10.95 at and on Amazon. All features mentioned in this blog will be keyed to the grid on the Field Map and will look like this: Plato: [NW/D9]

Courtesy of Gray Photography of Corpus Christi, Texas
Lunar photos: NASA / USGS / BMDO / LROC / ASU / DLR / LOLA / Moon Globe. Used by permission

Andrew Planck
Wrinkle Ridge Dorsum Oppel on the Moon and the Lunar Eclipse

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