Lab 9

Lab 9:
Lunar Features

Additional information may be found in the textbook in chapter 8, section 8.4 pages 187-192.

The moon is something that is easy for everyone to study in astronomy since it is so close to us as easily viewed. It has amazed and awed people over the years. Many of the features on the moon can be seen on a clear night even without a telescope. In this lab you will learn how to read a lunar map and locate many of the features.

The large dark areas are called maria which is Latin for seas. Long ago people thought that these areas were oceans on the moon surface so, they named them things like Sea of Tranquility, Sea of Dreams, Sea of Serenity. Later we discovered that these were not oceans, but large mostly flat areas on the moon. Since there are not many little craters in these areas, there is little for the light from the sun to bounce off of which is why these areas look darker.

Crater Formation - central peak

There are also craters on the moon which were made from various flying debris hitting the moon surface. Craters can be divided into two main catagories: flat bottomed or central peaked. A flat bottomed crater is just that, flat on the bottom. There are no other features that we can see. A crater with a central peak is a crater that has a small mountain that formed when the crater was formed. Something to notice is that the central peak is rarely in the exact center of the crater. The peak is made when something hits the surface of the moon so hard that the rock that is displaced comes back together with enough force to form a mountain. Think about a drop of water falling into a pond. When the droplet hits the water surface it creates an indention and the water spreads out in waves. Then the water comes back together where the droplet hits and there is a brief peak where the droplet was. The same thing has happened on the surface of the moon to create these peaks. (Reload the page to watch the animation.) There are also mountian ranges on the moon that are not peaks of craters.

Crater Formation - artist's
rendition

Craters can then be subclassified into rayed or non-rayed. Rayed craters are caused when something strikes the surface of the moon at an angle so that the rock and dust that used to be where the crater is gets thrown in all directions. Rayed craters look like there are streaks around it. Some of these craters have the rays all around them and some only have them on one side.

Any time you are not looking at a full moon or a new moon, you will have an area on the lunar surface called the terminator. This is the line of sunrise on the moon where the illuminated part of the moon meets the shadowed part. This is an interesting area to look at through a telescope because the shadows are long here and the features really stand out.

Lunar Map:

Identification of Lunar Features:

Look at the lunar photo provided for you. Each photo is of either the first or last quarter of the lunar cycle. The phase of the moon is written on the bottom of the photograph. Answer the questions on page 9-5 using the lunar map to find the names of the features you can see on the photo. Size of Lunar Features:

Height of a Lunar Mountain:

Your lab instructor will assign a certain mountain for you to measure and calculate its height. The mountian will be near the terminator. Measure the features described in the labbook in millimeters and multiply by the scale factor to get these measurements in kilometers. Use the formula in the book to calculate the height of the tiny mountains that you see. You will find that they are not so tiny after all!

Links:


Sky and Telescope Moontour www.skypub.com/sights/moonplanets/moontour.html	The Observatory gaul.csd.uwo.ca:8080/~mckaig/ moonphases/index.html

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