# Back-of-the-Envelope Calculations: Surface Area of the Moon vs. Earth

#### Summary

*Question*

If you could wrap the Moon in a gigantic cloth and then unwrap the cloth and spread it out on the Earth, how much of the Earth's surface would it cover?

## Assessment

*Answer*

An area about the size of the continents of Australia and Africa combined. The Moon has a radius of about 1740 km, giving the Moon a surface area of 4ð’

## 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

**Quantitative Skills**: Geometry and Trigonometry, Estimation

**Ready for Use**: Ready to Use

**Topics**: Solar system