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 Reference point in outer-space
Name: Helen F Roberts
Status: Other
Age: N/A
Location: N/A
Country: N/A
Date: N/A 

What is the reference point for an object's speed in outer-space?

Up until the 1940's this was a very deep philosophical question. Then the cosmic "microwave background" was discovered, and that sort of settled everything. This microwave background in space comes from the most distant points in space and time. It should look isotropic (the same in all directions) - but ONLY if you are at rest with respect to the average of those distant points. From the Earth there is a clear difference between the background in one direction and in the reverse direction (one is "red shifted", the other "blue shifted") which tells us our true velocity relative to the background. From all this it was discovered in the last decade or so that the local cluster of galaxies which we are part of is moving at quite high speed in the direction of a much bigger concentration of galaxies.

A Smith

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