Sky Viewer

Objective: To show how lunar craters formed

Materials:cocoa powder

flashlight

dual scale ruler

flour or talcum powder

Journal Page

marbles of different sizes

plastic container

plastic spoon

1 pair safety goggles

newspaper

Background: How did the craters that scar the moon’s surface form? On Erath, craters may form when a volcano explodes or collapses. Astronomers once thought lunar craters might have formed this way, since huge maria were filled with hardened lava when a rocky object or meteor strikes a planet’s surface, causing impact craters.

When a meteor crashes into a planet or moon, it becomes a meteorite. The impact makes rocks and soil fly in all directions. The meteorite usually breaks apart. Some of the pieces mix with the flying rock and soil. Others are buried in the crater.

A cupped shape depression forms. It has a raised edge, or rim, the rises above the ground. The rim is made up of the rocky material thrown upwards by the blast. The solid rock below the impact may melt from the heat of the impact explosion. Lava – hot melted rock – may pour out, fill the crater, and harden. The bright streaks, or rays, around young craters are made from material thrown out from the meteorite.

By studying the appearance of many lunar craters, scientist concluded the most formed as a result of impacts.

In this activity, you will model how lunar craters might have formed.

Method: Work with a partner.

  1. Spread newspaper on the table. Fill the plastic container to a depth of 2.5 cm (1 in.) with flour or powder. This stands for the original bedrock. Smooth the surface of the flour or powder with the back of the spoon.
  2. Sprinkle a thin layer of cocoa powder over the flower. This represents the lunar surface.

  1. Place the plastic container on the newspaper. Have a partner hold the ruler upright beside the container. Drop marbles of different sizes from a height of about 15 cm (6 in.). The marbles stand for meteors.

  1. Gently lift out the marbles. Try to not to disturb the surface. On your Journal page, describe the craters that formed. Draw a typical impact crater.

  1. Did the two layers mix at all? Did the material that flew out scatter evenly? What part of the “moon” did it come from? How can you tell? Compare the size of the craters with the marbles that produced them. Record your observations on the Journal page.
  2. Observe the carters using a flashlight to stand for sunlight. Put the light source to the side. Try higher angles and then place the light directly overhead. How do the shadows change? Record your observations on your Journal page.
  3. Try dropping marbles of the same size several times. Measure the impact crater with a ruler. What connection can you draw between a marble’s size and the features of impact crater it produces? Record your ideas on your Journal page.

Lunar Impact!

Describe the craters that formed when you dropped marbles of different sizes from above the model lunar surface. Record all your observations. ______

Draw a typical impact crater produced by this model.

What part of the moon did the material that flew out come from? ______

How can you tell? ______

How does the size of the crater compare with the size of the marble that produces it? ______

How do the shadows vary when you change the angle of the light shining on the craters? ______

What connections can you draw between the size of the marble and the features of the impact crater it produces? ______