Conceptual Physics (12th Edition)

Published by Addison-Wesley
ISBN 10: 0321909100
ISBN 13: 978-0-32190-910-7

Chapter 26 - Think and Explain: 66


The concept is explained in Figure 26.13.

Work Step by Step

The sun has a finite extent and is not a point source of light. When the plane is flying at a low altitude, its shadow is sharp because light coming from different parts of the sun doesn't get a chance to spread out much behind it before it hits the Earth. The shadow of a high-flying plane is filled in mainly by light tapering in from different parts of the Sun. This is the same effect responsible for the penumbra of a solar eclipse (page 495, Figure 26.15).
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.