Using Triangulation to Locate Meteorites from Witnessed Falls

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Author Contact Information

Andy Caldwell
Douglas County High School
2842 Front St.
Castle Rock, CO 80104
caldwell@tea.rice.edu

Overview
To expose students to the actual process of trangulating a meteorite fall through eyewitness accounts. Students should be able to produce a map and sketch of the fall area, with lines of sight of the eyewitnesses. At the end, they should find a "meteorite" that has been planted by the teacher. A piece of basalt or iron slag makes a good meteorite substitute.

Grade Level/Discipline
This activity is designed for high school students, although it has been performed by adults. It would work at any level that address the process of triangulation.

National Standards
Science as Inquiry Content Standard A: Abilities necessary to do scientific inquiry Understandings about scientific inquiry

Earth and Space Science Content Standard D: Energy in the earth system Geochemical Cycles Origin and evolution of the earth system Origin and evolution of the universe

Pre-activity set-up
The facilitator needs to find an area (like a football field or park) where the students can "sight" on objects on the horizon. The facilitator needs to determine at least three good places to interview "witnesses" and a location to seed the "meteorite." Make sure that this locale matches up with the witnesses statements. These interview locations should be in clear sight of specific objects on the horizon (like a tower, building, or mountain).

It makes it more fun for the students to role play if they have some sort of costume provided, like a hat.

The text of the interviews should be written out on notecards for the "witnesses" to act out.

For example: Farmer Bob (standing at bear statue): “I was out checking my livestock when a brilliant light appeared over the red light on that skyscraper to the southwest. I knew from taking the museum’s meteorite class that it was just a fragment of a protoplanet or asteroid.”

Pony Tail Penny (at fence): “I was out jogging when I saw this bright flash right over the Qwest building. At first I thought it was another UFO, but then I realized it was probably a stony chondrite.”

Engineer Fred (on sidewalk near lake): “I was driving my train through town the other night when I saw the bright flare right above the museum over yonder. At first I thought it was kids with fireworks, but I guess it was just a meteoroid reaching the point of retardation.”

Take the students to the search area and while the class is drawing their individual maps, instruct each of the "witnesses" about their task. Have students interview each of the "witnesses" and draw lines of sight after each interview.

The students should be able to find the "meteorite."

Materials
Teacher:

Hats (costumes)
"Meteorite: (rock, iron, ball, etc.)
Notecards with dialogue

Student:

Paper
Straightedge
Pencil

This activity can be made more accurate with a compass or protractor.

Time Frame
This activity takes about 20-30 minutes depending on the students questions and involvement.

Engagement and Exploration (Student Inquiry Activity)
Students are introduced to the scientific importance of meteorites. Many have witnessed bright fireballs in the sky, and often I ask them to talk about what they saw. The students are then introduced to true cases where witnesses are interviewed in an effort to triangulate the location of a meteorite. I often show them a map of Colorado with lines of sight drawn on it where witnesses spotted a meteorite fall. The students see how the lines converge at a single point giving the location of the fall.

Explanation (Discussing)
Students are asked to evaluate the interviews and discuss any flaws. One flaw is that the engineer is in motion. His perspective to the fireball is always changing, so his testimonial should really be thrown out.

They are asked what could make the interviews more accurate and how to improve the search. They could ask for first and last sightings or use a Brunton compass or protractor.

They are finally asked how this is like and dislike an authentic meteorite search. They should recognize that a real search involoves often hundreds of witnesses. Each testimonial must be weighed and compared with the rest to determine accuracy.

Elaboration (Polar Applications)
This activity mimics the process meteorite reseaches use to locate witnessed falls. This process has come to be called the "Nininger Method" after Harvey Nininger, one of the first meteorite hunters. Nininger traveled the American West in the 1930's and 1940's interviewing witnesses to falls, and giving guest lectures to whoever would listen. Often, there would be someone in attendance who had found a meteorite and would be willing to sell it to Nininger. Meteorite researchers and collectors still use this process today.

When a major fireball event occurrs, reports are taken online and evaluated by their location and credibility. A team of volunteers from the Denver Museum of Nature and Science goes out and interviews witnesses who are often hundreds of miles from each other. Any witness' testimony that indicates they were in motion, under the influence of alcohol, or didn't actually see the fireball has to be thrown out. Many witnesses see a flash of light, but don't actually see the fireball. Simply hearing it is also unacceptable.

The lines of sight are plotted on a map, and a search area is established for a ground search. Depending on the topography and ownership of the propery, the volunteers will either conduct a foot search for the meteorite(s) or will educate the local residents as to the characteristics of meteorites. The latter procedure is actually more effective.

Exchange (Students Draw Conclusions)
The students produce a map showing lines of sight of the witnesses. They can evaluate the accuracy of their maps by how closely the lines converge.

Evaluation (Assessing Student Performance)
Verbal questions. Accuracy of sight lines. Parcticipation and further questions from the students. Acutally locating the "meteorite."

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