The week of January 22-28 takes us from Day 12 to Day 18. This week we will highlight Mare Orientale on the moon, viewable on Tuesday.

Mare Orientale on the moonCordillera Mountains - outer ring for Mare Orientale on the moonMare Orientale/Cordillera Mountains: [SW/L-M libration zone; L=82°W] It is a pity that we are deprived of a decent view of Mare Orientale; it is the Moon’s greatest and most pristine example of a multi-ring impact basin. But count your blessings; the tradeoff for a permanent view of the far side would leave us worse off. It would be like staring at vast, unbroken stretches of the Southern Highlands. Mare Orientale, however, does shyly reveal herself, if only in part, when libration is favorable. At such times you can glimpse its outer ring, the Cordillera Mountains, and sometimes even its inner ring, the Rook Mountains.


On January 28, 1986, the space shuttle Challenger explodes, killing a crew of seven.


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
Mare Orientale: Moon’s Greatest and Most Pristine Example of a Multi-Ring Impact Basin

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