The Moon’s Eastern Seas Part 1: Formation & Evolution of the Moon Part 2: Lunar Libration Part 3: The Eastern Seas

Geologic timeline of Earth 4570 Earth Formation 1800 First Complex single-cell life 380 First Vertebrate Land Animals 230-65 Dinosaurs 80-55 Rocky Mts. Uplift 0.0117 Glaciers Retreat

Geologic timeline of Moon & Earth 4570 Earth Forms 4533 Moon Forms from Giant Impact

Formation & Evolution of the Moon Nectarian Nectaris, Humboldtianum, Humorum, Crisium, Serenitatis Pre-Nectarian Procellarum Insularum Marginis Fecunditatis Australe Tranquillitatis Nubium Smythii Grimaldi NECTARIS IMBRIUM Imbrian Eratosthenian Copernican ERATOSTHENES COPERNICUS NOW Pythagoras, Theophilus, Langrenus, Hercules Tycho, Aristarchus, Kepler ORIENTALE Lava Flows Surface Hardens Late Heavy Bombardment

Timeline for Lunar Lava Flows NECTARIS IMBRIUM COPERNICUS Nectarian ERATOSTHENES Pre-Nectarian ORIENTALE 50 40 NOW Lunar Volcanic Activity Basalt Units 30 20 10

Beginning of the Late Imbrian Period Drawing by Don Davis

End of the Late Imbrian Period Drawing by Don Davis

Present Day Moon Drawing by Don Davis

Lunar Libration

Lunar Directions N W E S

The Eastern Seas N E In early February the 6-day-old Moon was Librated so that more of the eastern area was visible than usual.

Mare Humboldtianum

Mare Humboldtianum Located in the Moon’s NE Corner Outer Basin is 600 Km in Diameter Formed during the Nectarian Period Inner Basin & Mare are 300 Km in Diameter The Basin formed during the Nectarian Period, and filled with lava during the Late Imbrian Named for Alexander von Humboldt by Johann H. Mädler Lunar Periods Late Heavy Bombardment

Alexander von Humboldt Johann Heinrich von Mädler (May 29, 1794 – March 14, 1874) one of the great and eminent astronomers of the 19th century. Has a crater on the Moon and one on Mars named for him. (September 14, 1769 – May 6, 1859) was a Prussian geographer, naturalist and explorer. Humboldt's quantitative work on botanical geography laid the foundation for the field of biogeography.

Mare Smythii,

Mare Smythii One of the lowest Maria, 4 – 4.5 Km below the avg. Lunar Surface Impact basin is Pre Nectarin, 350 - 400 Km in diameter Southern floor is late Imbrian basalt. Northern floor is from the Eratosthenian period & may be only 1 – 2 billion years old. Named for Admiral William Henry Smyth (21 Jan. 1788 – 8 Sep.1865), English naval officer & astronomer. President Royal Astronomical Society. Published Bedford Catalogue with observations of 1604 double stars and nebulae (with a 5.9-inch refractor).

Mare Marginis

Mare Marginis (The Sea of the Edge) Thought to be one of the oldest Maria on the Moon. About 200 Km north-to-south. Apparently not area with a major impact basin. Appears to be a low-lying area where lava filled several cratered areas where the lunar crust was relatively thin. The lava flows are also thin, being only an estimated 1000 to 1700 feet thick. The highland area is Pre-Nectarian and lava flows are probably Late - Imbrian

Mare Anguis, Undarum & Spumans

Mare Anguis Mare Undarum Mare Spumans (Serpent Sea) (150 Km long) (Sea of Waves) (240 Km dia.) (Foaming Sea) (140 Km dia.) All three Maria are of Nectarin origin, with lava filling them during the Late Imbrian Period.

Mare Australe (The Southern Sea) This 600 Km heavily-cratered basin was formed during the pre-Nectarin period, and filled with lava during the late Imbrian period. The basin is located in the Southeast area of the moon, and half of the basin is on the far side, but can be seen (barely) during favorable librations.

References The Modern Moon – a personal view By Charles A. Wood The Geologic History of the Moon (US Geological Survey Professional Paper 1348) –By Don E. Wilhelms Wikipedia “Eastern Seas” photo taken with 6” f/8 Refractor at prime focus, Canon Rebel DSLR, ISO 100, 1/250th second http://www.lpod.org/cwm/DataStuff/pronounce/Introduction.htm

The End! Questions?