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By Jane Houston Jones
Published 2004-09-06 11:43:32

Fasten your seat belt. You're going on a guided tour of a lunar day. We'll describe what lunar features can be seen during the phases of the moon. Use this diary all year to sketch the moon each day, while observing the seas or plains, mountains, impact craters and shadows on the moon. You'll be surprised at some of the familiar geology you'll see on our rocky neighbor.

New Moon Phase Day 1 - 6 "Rises at dawn, sets at dusk" New moon means the instant when the moon is visible in its conjunction with the Sun. This is the starting point of the lunation or period of the Moon's cycle around the sky. Day 1 is very difficult to observe. On day 2, the "sea" of crises, Mare Crisium becomes visible. The old word "sea" has been replaced by the more descriptive and geologically correct"plain". To the south is Petavius, a large crater with a central peak of over 8000 feet. Day 3 brings Mare Fecunditatis, south of Mare Crisium, into view. On day 4, Crisium and Mare Fecunditatis are fully visible, and the walled plain Janssen is visible. On day 5, Theophilus and Cyrillus make a nice pair of craters. The crater Maurolycus, with a central peak like Theophilus, appears on day 6. The moon is now approaching first quarter. The terminator (boundary between the sunlit and dark parts of the moon) is now at the center of the moon's disk.

First Quarter Phase Day 7 - 13 "Rises at noon, sets at midnight" The crater Hipparchus is at its visible best near the terminator on day 7 as is the mountain Piton, with its prominent peak at the terminator tonight. Look for two craters within Hipparchus. Day 8 brings into view the rugged Appenine mountains, and to the north the oval walled plain Plato. With binoculars or telescopes, find the "Straight Wall", a lunar fault line. Tycho and Copernicus are on the terminator on day 9, and so is Clavius, the large walled plain south of Tycho. On day 10 look for the Jura Mountains and the Sinus Iridum (the bay of rainbows), a hooklike curved mountainous point on the edge of Mare Imbrium. This is one of my favorite objects on the moon to observe and sketch. On day 11 observe the lunar plains. On day 12, look at Gassendi, a large crater. As full moon approaches, look back over the objects you observed each night and see how different they look.

Full Moon Phase Day 14 - 21 "Rises at dusk, sets at dawn" Look at the ray system tonight. The brightly illuminated moon washes out all other observing projects so you might as well enjoy the moon tonight. The rays of Tycho are the best! Day 15 brings sunset to Crisium, 2 weeks after we first viewed its sunrise. Watch the shadows cast on the walls of the plains including our darkened Mare Crisium, and craters on day 16 through 18. Day 19 is the best day to view the "Sea" of Tranquility, famous as the landing site of Apollo 11. See the next page for exciting details about locating the lunarlanding sites. Day 20 brings the terminator to another of my favorite observing and sketching sites, the three craters Theophilus, Catharina and Cyrillus. Mountains are the highlight of day 21. The Apennines, and the large craters Kepler, Copernicus and Tycho are beautiful at lunar sunset. The last quarter moon has arrived.

Last Quarter Moon day 22 -27 "Rises at midnight, sets at noon" Dedication is required to complete the viewing of the lunar cycle. Mare Imbruim and Copernicus are darkening tonight, day 23. On day 24 through 27, most observers are sleeping when the moon is visible. Use binoculars to observe earthshine over the surface of the moon. These are the days (or rather nights) to turn your eyes, binoculars or telescopes to other wonders of the night sky: planets, comets, meteor showers and galaxies. Then, say good-night to our close neighbor, and with a sense of wonder and accomplishment, have a good sleep!