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 How Bright Do Stars Shine 
Name: janette l gubala
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: 1993 - 1999
Question:
How bright do stars shine?

Replies:
The brightness of stars as seen from the Earth is called "apparent visual magnitude"; it is designinated by "m subscript v" and is a logarithmic scale like the Richter scale used for earthquakes. The brightest star seen from the Earth's northern hemisphere is Sirius, the Dog Star with a _m subscript v_ of -1.5 (the stellar magnitude scale is one in which a negative number is brighter than a positive number).

The absolute visual magnitude, designated by "M subscript v", gives the true brightness:

Deneb (alpha Cygnus) has Mv = -6.9, and Rigel (beta Orion) is almost as bright with Mv = -6.8.

On the absolute scale, Sirius is only Mv = +1.4; it *appears* to be the brightest because of its nearby distance, only 2.65 parsecs.

Hawley


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