Planetary Geology pdf - NASA

c. What do you suppose would happen to the large crater if you left it in the rain for 5 minutes (10 times
as long)?
d. Are there more or fewer overlapping craters here than in the first dish?
Make another ÒfingerÓ crater in each of the other two dishes. Place one dish in the rain for two minutes; the
other for four minutes. Make sure you pour the water slowly or you will form a lake in the petri dish!
3. a. What has happened to the large craters? Does this agree with your prediction from question 2c?
b. Which dish has the most small craters?
c. Is there a marked difference between the two dishes, allowing you to easily tell which dish spent the
most time in the rain?
The angle of illumination affects the visibility of surface features. Surfaces lit from directly overhead (noon
time) appear different from those lit at an angle, as during sunrise or sunset. Line up the four petri dishes with
their raindrop craters. Turn off the overhead lights. Use the flashlight and shine the light across the surface of the
dishes, estimating the illumination angle. Try shining the light from the following angles and describe what
you see. Examine the dishes from two locationsÑfrom the position of the flashlight and from directly above
the dishes.
4. a. 90¡ (directly above the craters)
b. 45¡
c. 20¡
d. 10¡
Examine Figures 6.3 and 6.4.
5. a. Based on Figure 6.3, list the evidence you see on the Moon for long term impact cratering.
b. Is the surface shown in Figure 6.4 older or younger than the surface seen in Figure 6.3? How can you tell?
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Exercise Six: Impact Cratering on a Rainy Day
Activities in Planetary Geology for the Physical and Earth Sciences EG-1998-03-109-HQ