Quantitative Skills > Teaching Resources > Activities > BotEC: Approaching Asteroid

Back-of-the-Envelope Calculations: Approaching Asteroid

Barbara Tewksbury

Hamilton College
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Summary

Question

If asteroids careen through the solar system at 25 km/second, how far away would we have to detect one in order to have a year's notice to prepare for an impact, as was portrayed in the movie Deep Impact? How far away is that relative to the planets in our solar system?

Assessment

Answer

More than 3/4 of a billion kilometers away (about 788 million kilometers, actually), which is about the distance from the Earth to somewhere between the orbits of Jupiter and Saturn. 25 km/second is 90,000 km/hour. With 8,760 hours in a year, the asteroid would travel 788 million kilometers in a year.

References and Resources

This SERC page describes the use of Back of the Envelope Calculations

A View from the Back of the Envelope (more info) : This site has a good number of easy simulations and visualizations of back of the envelope calculations.

The Back of the Envelope : This page outlines one of the essays in the book "Programming Pearls" (ISBN 0-201-65788-0). The book is written for computer science faculty and students, but this portion speaks very well to back of the envelope calculations in general.

Controlled Vocabulary Terms

Subject: Geoscience:Lunar and Planetary Science
Resource Type: Activities:Classroom Activity:Short Activity
Special Interest: Quantitative, Hazards
Quantitative Skills: Estimation
Ready for Use: Ready to Use
Topics: Solar system

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