Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Equal Day/Night Everywhere
Name: Sarah P.
Status: student
Age: 14
Location: N/A
Country: N/A
Date: Tuesday, May 21, 2002

At the time of the spring and fall equinoxes, there are 12 hours of daylight and 12 hours of darkness all over the world. The dates of these are?

This NEVER happens. For example, the poles have one sunrise and one sunset each year. There is never a 12 hour day, 12 hour night at the poles.

Due to atmospheric refraction, there is never a single date in the rest of the world for such an occurrence.

Many "standardized" tests make this error, as do texts.

In Chicago, IL 12 hour day/night occurs about 17.March. In Southern Brazil, this happens about the 23.March.

Nate Unterman

Click here to return to the Astronomy Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory