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 Sidereal Day 
Name: Marlene
Status: student
Age: 12
Location: N/A
Country: N/A
Date: 10/5/2003
Question:
What is a sidereal day?

Replies:
The sidereal day is the time the Earth takes to rotate 360 degrees, that is in relation to the stars. It is 23 hours 56 minutes 4.09 seconds in length when one compares it with mean solar day which is 24 hours in length. [The Earth rotates 360.98 degrees in 24 hours.]

The difference is caused by the Earth's orbital motion, and that the Earth travels around one reference point [the mean Sun], but not the other [an extremely distant star or stars].

Howard Barnes


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 (help@newton.dep.anl.gov), or at Argonne's Educational Programs

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

Argonne National Laboratory