A DAY IN THE LIFE
OF THE MOON
by Jane Houston * moon animation created by Ed Stephan email@example.com used by permission
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 The old word “sea” has been replaced by the more descriptive and geologically correct”plain”.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!
QUESTIONS AND ANSWERS
Questions arise when Amateur Astronomers are out with their telescopes sharing the universe with the public. Here is a recent question and the answer, which took me a while to find.
Q: Do you know where Mount Marilyn is on the moon? (Mount Marilyn is the feature mentioned in the movie Apollo 13. It is fictional, but represents a real lunar feature.)
A: Mount Marilyn is on the southeastern edge of the Sea of Tranquility, near the crater Secchi, as mentioned in the Apollo 13 book. Most lunar maps don’t show Secchi, but do show Taruntius to the upper northeast of this little crater. The Apollo 11 landing site on the lower western edge of the sea and the landing site of Apollo 17 at the top of the sea form a triangle with Secchi. Mount Marilyn is the mountainous feature to the right of Secchi.
APOLLO LANDING SITES ON THE MOON
Have you ever been asked “Can you see where men landed on the moon”? Even with a small telescope, you can pinpoint some of the landing areas. I will describe how to “crater hop” to the sites below. A detailed moon map will help.
Apollo 11 Find the crater Julius Caesar to the left of the Sea of Tranquility (Mare Tranquillitatis). Below and to the right are two unnamed craters joined to look like the number 8. Directly south are the twin craters Ritter and Sabine. Apollo 11 is about 3 Sabine sized crater widths to the right of Sabine. Three tiny craters above the site are named Aldrin, Collins and Armstrong after the Apollo 11 astronauts. The best days to look is about 5 or 6 days after the new moon or 4 or 5 days after the full moon.
Apollo 12 landed in Mare Insularum, about two crater widths southeast of the crater Lansburg.
Apollo 14 landed north of Fra Mauro, a ringed plain that sits at the boundary between Mare Insularum and Mare Cognitum. The best time to see this this plain is at the waxing gibbous or waning crescent phase (Days. 7-13 and 22-27) described above.
Apollo 15 Find the crater Archimedes to the left of the Appenine mountains. Between the crater and the mountains is a feature called Hadley Rille. When this area is in shadow, on day 20 or 21, you will see the undulating rilles. This rille is just west of the Apollo 15 landing site. To Astronauts Dave Scott and Jim Irwin, this was a very steep climb on their exploration of the lunar surface.
Apollo 16 landed in the Descartes highland. Look one crater width north of Descartes to find the site.
Apollo 17 Find the eastern shore of Mare Serenitatis. The site of Apollo 17 lies between the craters Littrow and Mons Argaeus in the Taurus-Littrow Valley.
There were 4 Apollo orbital test missions, 2 around the earth and 2 around the moon before the first moon landing with Apollo 11 on July 16th, 1969. There have been 18 men who went to the moon on the Apollo 11, 12, 14, 15, 16 and 17 missions, but none of them saw the full moon and full earth as depicted in the “Apollo 13” movie. We see a full moon when the Earth is between the sun and the moon. The lit side of the Earth will not be visible on the moon.