Moon Watching

You don't need a huge telescope to do moonwatching and it can be very rewarding. Binoculars and small telescope do just fine. You can make drawings of what you see on the lunar surface and it will likewise train your eye to see even more details. The angle of light and shadow changes from lunar phase to lunar phase and different features are best viewed at different times. We've broken down phases from new moon to first quarter and then first quarter to full moon. Use the maps and images to find your way around. But don't forget that most telescopes invert the moon's image!

There are around 300,000 craters larger than 1 kilometer on the side of the Moon facing us. The average crater is nearly circular depression which may have a central peak. Many craters have terraced walls. There are also walled plains which may have some craters. There are crater chains, the largest of which stretches nearly half the diameter of the Moon. Often craters will overlap other craters. And there are countless small craters which will only be visible with larger telescopes.

Observing new moon to 3 day old Moon

A few days after new moon you can start to look for details as the crescent becomes more and more visible in the evening sky. When there is just a very slim crescent, it's a great time to look for earthshine on the unilluminated portion of the Moon. This is what we call the "Old Moon in the New Moon's arms." Earthshine is caused by sunlight being reflected off the Earth and falling onto the Moon. It is difficult to make out lunar features in the Earthshine lit portion but you can usually see places like Aristarchus. Even with the unaided eye, one can make out light and dark areas, the dark areas being what were long ago named maria, or seas because that is what they were believed to be. Binoculars or a telescope will show these maria to be lunar plains.

Larger Image of Moon Features

Mare Crisium is a circular shaped feature that is large and easily recognized. Just north of it is a large crater named Cleomedes. When the Moon is about 3 days old, a telescope will reveal small craters in the floor of Cleomedes. These small craters will only be visible for a day or two, after that, the crater floor is flooded with sunlight and they will be impossible to see. Also in this large crater is Cleomedes Rille, but you would need a larger telescope to see it. South of Crisium is another sea, Mare Fecunditatis and in the middle of Fecunditatis is Langrenus, a crater 126km across. This crater has two large central peaks and terraced walls. Further south of Langrenus is a ring mountain called Petavius which has eroded walls. It has a great central mountain chain.

North and west of Mare Crisium is Proclus, a crater surrounded by a bright ray system. As we move to a 5 or 6 day Moon, two more large Maria come into view, Tranquililitatis and Serenitatis as well as more of Fecunditatis. There are two oval shaped craters in Fecunditatis you'll want to look at called Messier and Pickering. Both of these two craters have ray systems also. If you can catch the shadows just right you will see many more smaller craters there also. Many of them are quite faint, having long ago been filled by lava flows. Mare Tranquilitatis, the Sea of Tranquility, has interesting faint features also, one being Lamont. Lamont is just north of the three small craters named after the Apollo 11 crew. Also in this mare are what's called wrinkle ridges. These can best be seen when the angle of the light coming in is low.

South of the Sea of Tranquility is feature called Nectaris, a circular shaped mare. On the western edge of Nectaris is a beautiful crater chain of Theophilus, Cyrillus and Catherina.

Observing first quarter to full moon

When the Moon is about half full three of the Moon's main mountain ranges come into view. These are the Alps, Caucasus and the Apennines. There is a lava plain in a gap between the Apennines and the Caucasus mountains. On this lava plain are the craters Autolycus, Aristillus and Archimeded, the latter being the largest. Although Archimeded has nicely terraced walls, much of the crater has been filled with lava.

In the north is Cassini, another roundish crater that has been flooded with lava. After flooding, the area suffered additional impacts, the larger called Cassini A. A small telescope will reveal other small internal craters. South of this, almost in the middle of the Moon is a crater chain consisting of Ptolemaeus, Alphonsus and Arzachel. Ptolemaeus is a large walled plain about 153km across. The small crater on the floor of Ptolemaeus is Ammonius.

The mountains in the north give way to Mare Imbrium, beginning just west of the Alps, Caucasus and Apennines. In the northern boundaries there is bright terrae material along with Plato another flooded crater. South of Imbrium is the Mare Insularium with the large, easily recognized crater Copernicus. This crater has central mountains and terraced walls. Around Copernicus is a massive ray system, best viewed when the Moon is about 9 days old. . Northeast of Copernicus is Eratosthenes. .

There is a long chain of craters starting around Ptolemaeus, Alphonsus and Arzachel. South and slightly west of that chain is the brilliant crater Tycho. Tycho has an even more massive ray system than Copernicus. South of Tycho is the large walled plain system of Clavius. Just north of Tycho is Mare Nubium.

An interesting feature within this sea is the Rupes Recta, or the Straight Wall. For this feature to look like a straight wall, the lighting has to be just right, but this is not wall, rather it is just a geologic fault.

North of the straight wall is the formation of Fra Mauro, the spot where Apollo astronauts played golf in 1971.Southwest of Fra Mauro is the Mare Humorum within which is the walled plain Gassendi. Gassendi has many clefts, hills and mountains in and around it.

Going a bit further north we run into the huge area called Oceanus Procellarum in which we can find the bright area, Aristarchus, also with a bright ray system. Beside Aristarchus is a flooded crater called Herodatus which has a feature looking like a squiggly line called the Schrofers Valley. The valley then meanders for a hundred and sixty kilometres before terminating to the north west of Herodatus.

Larger image of Nearly Full Moon

When the Moon is nearly full it is time to look west of Aristarchus to a flooded plain called Struve. Some features you spotted when the Moon was younger are either no longer visible or too hard to spot because of the brightness. This is a good time to view the bright rays around Proclus, Kepler, Copernicus, Aristarchus and Tycho.

When the Moon is past full the shadows will begin forming on the earlier features you spotted. The angle of light and shadow change every night with the Moon and it is worthwhile to compare how the features change from phase to phase. One of the best ways to do this it to sketch the Moon.

Drawing the Moon

With a little practice anyone can draw the features they see on the Moon. The first thing to do is make sure you have a comfortable position to view and sketch. Have something to lean your sketchbook on, such as a small table or even just a board. Get an assortment of soft and hard pencils as well as an eraser (a kneadable eraser is recommended.) Get a good drawing tablet with fairly fine-grained paper. You will need some light to sketch by also. We recommend using a red lightbulb if you can get one or if not, use about a 25 watt regular bulb. Do not refer to the charts while you are sketching though. You want to sketch the Moon as you see it.

Larger Sketch

Choose an area on the Moon to sketch. Don't get too large an area or the drawing will take too long. Sketch large! People tend to sketch small, and this makes it harder to put in details. Start out by using a low power eyepiece and lightly sketch in the mail outlines of craters or maria. Then use a higher power eyepiece to reveal more details which you can then add to your drawing. Put shadings and shadow in last. Be sure to record the date and time of your drawing, along with telescope and eyepiece details and viewing conditions.

Constellations

The Solar System