Nineteen states have passed legislation to make daylight saving time permanent. But those laws won’t take effect until Congress makes it legal. And the medical community sees one major problem.

  • The tropics is the only area on Earth where the Sun will ever be directly overhead. The sun’s average position is directly over the equator and the wobble in the Earth’s rotation let’s it’s absolute position vary about 23.5° north or south which is what defines the tropics.