Mons Rümker dome on the moonThe week of October 2-8 takes us from Day 12 to Day 18, spanning the full moon. This week we will highlight Mons Rümker, visible on Monday night. (This was featured in the 5/22/17 Blog, but it could only be seen in the early hours just before dawn.)

Mons Rümker dome on the moonMons Rümker: [NW/E4] Unfortunately this feature is too close to the Moon’s limb to see it very clearly, so coordinate your viewing with a favorable libration (which will be the case on Monday night). In spite of its name, Mons Rümker is not really a mountain, it’s an extensive complex of domes, so the low-lying Sun on Monday evening should help bring them out. The diameter of the formation is over 40 miles. Although there are about a dozen domes here, through a telescope it looks like a mound with a bumpy surface. Several of the domes have summit pits. Can you make any of them out?


Venus and Mars are in conjunction in the pre-dawn hours of Thursday morning. They are only about ¼° apart. It may be difficult to separate them naked eye because of the brightness of Venus, so use binocs or a low-power telescope.


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

Andrew Planck

Author and Astronomer Andrew Planck shepherds you to the moon and its mysteries of intrigue and surprise. Learn about the moon’s most fascinating objects, understand how the moon was formed and the names of many of the craters … and why they honor individuals who have changed the course of history.
Andrew Planck
Mons Rümker: Extensive Complex of Domes on the #Moon

Leave a Reply

Your email address will not be published. Required fields are marked *