Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Have you ever wondered why leaves change color in the fall? Watch this quick clip where Dr. Kevin Smith explains why change happens.
Last updated March 31, 2025
