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Impact Craters

Activities|Age/Grade|Facts|Fun|Links|Objectives|Questions|Quiz|Related Topics|Summary|Vocabulary

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Summary of Article

An impact crater is caused by a celestial object (meteorites) that enters the atmosphere and fails to burn up. This article describes several impact craters found on Earth and in the heavens on many different planets. It also looks at the extinction impact of 65 million years ago, and dares to ask the question, "Are we in danger?"

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Suggested Age/Grade Levels

Age Level: 13 - 15
Grade Level: 7th grade - 9th grade

Related Topics

Earth Science
How do meteorite impacts change the environment? Biology
Investigate extinction events that correspond with celestial impacts. Geology
How many large impact events can be found in the rock layers of the Earth?

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Objectives

After studying the article, students should be able to:
  • Tell the difference between comets and asteroids.
  • Understand that impact events take place on Earth, as well as on other planets and moons.
  • Identify the Yucatan Peninsula as the site where a major impact event occurred.

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Classroom Activities

Classroom Craters
Materials:
  • Plastic drop cloth (at least 3' x 3')
  • One 9" x 13" (or larger) metal pan (not glass)
  • Sand to fill the pan
  • One 12-inch ruler
  • An "impacter" (marble, rock, or other small object)
  • Graph paper (several sheets per student)

Place the drop cloth on the ground and the pan on the drop cloth. Put the sand in the pan, smoothing the surface with the ruler. Drop the impacter from a height of at least 10 feet into the pan. Observe the crater made by the impacter. Have students carefully measure and graph the crater on their graph paper and note the distance that sand was ejected from the pan.

Remove the impacter and smooth the sand with the ruler. Repeat the impact experiment with the impacter dropped from a higher point (20 feet is recommended -- you may need to drop the impacter from windows on different floors of a building). Have the students measure and graph the crater and ejected material once again.

Compare the recorded craters. Ask the students to estimate the crater size that would be produced from the same impacter dropped from a height of 30 feet (you may ask them to graph their estimates). Conduct the experiment again, this time dropping the impacter from a height of 30 feet. Graph and compare the actual impact with the students' estimates.

For more lesson plans and suggested activities, please visit the NASA lunar homepage, which has an entire section dedicated to educators (includes teacher's guides).

http://lunar.arc.nasa.gov/education/lessons/index.html
*You must have Adobe Acrobat Reader on your computer to download the information.
Click here to download Acrobat.

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Questions for Discussion

Q: What is a meteor?
A: A meteor can be interplanetary dust, rock, or debris as it passes through our atmosphere and is heated to incandescence. Meteors are often called shooting stars.

Q: What is a meteorite?
A: A meteorite is a meteor that actually falls to the ground. Most meteors burn up and never make it to the ground.

Q: What is a meteoroid?
A: A meteoroid is the dust, rock, or debris still in space. It could be a chunk of an asteroid or comet.

Q: What is a comet?
A: A comet is a very old body of ice mixed with rock and organic material.

Q: What is an asteroid?
A: An asteroid is an irregularly shaped object made of either iron-rich silicates, carbon-containing materials, or metals like iron and nickel.

Q: Is the Earth in danger of being hit with an object like the one that caused the Chicxulub impact in the Yucatan Peninsula?
A: The Earth is getting hit with objects every day. Most of these objects are the size of dust particles, although some are somewhat larger. Virtually all burn up in the atmosphere.
There is a very low probability that an object like the one that caused the Chicxulub crater will strike the Earth again. If a large celestial body is found that could eventually threaten the planet, it is added to a catalog and a watch is maintained on it.

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Quiz

Click here for an Impact Craters quiz.
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Just the Facts

Fragments of the comet Shoemaker-Levy 9 struck Jupiter in 1994. No impact craters were formed because Jupiter is a mostly gaseous planet.

Maps of impact craters show that they are clustered around North America, Europe, and Australia. This is only because those continents have been more thoroughly searched.

Impact craters can be found on other planetary bodies such as the Moon, Mercury, Mars, and many of the moons of the planets of the outer solar system.

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Links to Relevant Web Sites and Additional Resources

http://observe.ivv.nasa.gov/nasa/exhibits/craters/impact_links.shtml

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Vocabulary

impact crater: a hole carved into the ground by a celestial object that survived its descent through the atmosphere.

cryptoexplosive features: concentric and radial faults encircling an uplifted area of broken-up and heated rock.

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For Fun

Just for fun, play our Impact Craters Wordsearch game.
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