I. Introduction

The Earth’s Moon is an extremely important solar system object. Thanks to the return of rock samples during the Apollo program, we have a better idea of the geology (or more accurately, selenology) of the Moon than of any other astronomical object. Analysis of these samples, together with telescopic studies of the surface of the Moon, have allowed us to deduce important conclusions about the early history of the solar system.

In addition, the Moon presents a spectacular sight to the observer with a small telescope. He or she can explore the unlimited number of fascinating features on the surface of the Moon.

The purpose of this project is to observe the Moon, both with the naked eye and with a Celestron 8 (or comparable) telescope. The naked eye observations are intended to show you where the Moon is relative to the stars, and thus the ecliptic. You can also use the SC1 chart to infer where it is relative to the Sun.

The telescopic observations are intended to show you the surface of the Moon in some detail, and allow you to see the major types of lunar features such as craters, maria, crater rays, and lunar mountains.

Ideally, this observing project will be done on two consecutive weeks, when the Moon is between new and full. This will permit you to see how the Moon moves against the background stars, and give a more complete idea of the nature of its orbit. These consecutive observations are also worthwhile for the telescopic observations, since you will be able to see the same features under different illumination conditions.

II. Moon Maps

The purpose of the telescopic observations will be to identify and draw some feature on the surface of the Moon. For this you will need a map of the Moon so you know what you are looking at. A simple map of this sort is given below.

You should look at these other possibilities as well.

There is a map of the Moon on p51 of your lab manual, in the exercise “Lunar Topography”.
A photograph of the Moon with features identified is available on the web at http://www.oarval.org/MoonMapen.htm
Finally, the best choice is the “Lunar 100” card showing a map of the Moon and the best 100 features, available from Sky Publishing Corporation. We may be able to provide these to you.

III. Naked Eye Observations

Locate the Moon as well as you can relative to the background stars. Use the SC1 chart for help. If the sky is hazy or badly light polluted, this part may be impossible. This part of the lab exercise should be carried out on both nights. If it is clear enough to see some stars in the vicinity of the Moon, write down here the location of the Moon relative to the stars. ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………From this, estimate roughly the Right Ascension and Declination of the Moon at the time of your observations.

Right Ascension:………………………………………………………………………….

Declination:………………………………………………………………………………...

Finally, estimate the position of the Moon relative to the ecliptic. This will be possible if the Moon is fairly close to bright stars near the ecliptic. If conditions are good enough, judge whether the Moon is on the ecliptic, below the ecliptic, or above the ecliptic.

………………………………………………………………………………………………………………………………………………………………………………………………

IV. Telescopic Observations

This part consists of viewing the Moon through the eyepiece of a Celestron 8 telescope. At least two eyepieces with different magnification will be used. The magnification is determined by the focal length of the telescope (the distance between the lens or mirror and the point where the light rays come to a point) F1, and the focal length of the eyepiece F2. The magnification of the telescope is then given by M=F1/F2. A Celestron 8 has a focal length F1=2000 millimeters.

The first eyepiece will have a focal length of 25 to 30 millimeters, and thus has a fairly large field of view. The second should have a focal length of about 10 millimeters, and provides higher magnification. Observations with this eyepiece allow you to see greater detail on the surface of the Moon.

First, identify an object or feature on the surface of the Moon. The choice is yours. You can do this either by picking it ahead of time from the Moon maps above, or you can look through the low-power eyepiece at the Moon, pick some feature of interest and identify it on the map. You should also classify this feature, if you can, as a crater, a mare, or something else.

After you have identified it, give its name here:……………………………………………………………………………………

If this project is done on two successive weeks (preferred), then observe the same feature both weeks, and draw it both times. Comment here on any differences you see. ………………………………………………………………………………………………………………………………………………………………………………………………

For second week only. Pick a second surface feature or object, and draw it, too. Give the name of this object here. ………………………………………………………………………………………………………………………………………………………………………………………………

In the space below, give a reasonable sketch of the appearance of the object at both low and high magnification. Label any features of interest.

V. Drawings of Lunar Features