**Investigation: What if Earth and the Moon were hit
by twin asteroids?**

You will be following through with an investigation on the computer at www.classzone.com Follow the steps provided in order to go through the investigation correctly. Along the way there will be questions for you to answer. The questions are written below so you will know your location and you do not get lost.

**Start Here:** Go to **http://earthsci.terc.edu/navigation/home.cfm**

On the left hand side of the screen is a box for a keycode.

Enter:
**ES2506** and click enter.

Observe the pictures and the locations they are from.

1. Predict what would happen if twin asteroids, each 1000 meters in diameter, were to collide with Earth and the moon. Include a description of the impact craters you would expect to see on each body.

2. What do you think the two craters would look like ten million years in the future?

3. Earth and the moon are spheres, but to
an incoming asteroid they appear as circular targets. Find the area of each
target using the formula Area =*πr ^{2}*, where

Diameter of Moon = Radius of Moon (r) =

Diameter of Earth = Radius of Earth (r) =

Calculate the "target
area" of Earth and the moon. * Use the calculator on the computer.*

Area of Moon = 3.14 x r^{2
}=

Area of Earth = 3.14 x r^{2
}=

How many times larger a target is Earth than the moon?

What does this say about Earth's chances of being hit by an asteroid compared to the moon's chances?

Compare the landscape in this photograph to the landscape where you live. Notice the many small craters pictured here, some as small as a few centimeters in diameter. What do you think might happen to the object that created one of these small craters if it were headed toward Earth?

4. How do you think an ocean impact would differ from an impact on land?

5. Describe the surface processes that work to erase craters and other impact features on Earth and the moon.

6.
The acceleration of gravity (g) on Earth is 9.8 meters/sec^{2}, but on
the moon, it is only 1.6 meters/sec^{2}.

How might this relate to the sizes of craters produced by impacts with identical amounts of kinetic energy on the two bodies?

Use the Impact Calculator to answer these questions.

7. What happens to the crater diameter when you increase the speed of the asteroids?

8. What happens to the diameter of impact craters as the impact angle decreases?

9. How does the kinetic energy of a 1000 m diameter iron asteroid traveling at 17 km/sec compare to the kinetic energy of an iron asteroid at twice the mass (diameter of 1260 km) traveling at the same speed?

10. How does the kinetic energy of a 1000 m diameter iron asteroid traveling at 17 km/sec compare to a similar one traveling at 34 km/sec?

11. Use the Impact Calculator to determine the size and structure of craters on Earth and the moon produced by asteroids with 500 m diameters at different speeds, impact angles, and compositions. Make a table on a separate sheet of paper to record your results.