How do astronomers measure the brightness of stars?
When you look at the night sky, you see several stars, some of which are bright and others faint. A star could be faint either because it is inherently less luminous, OR because it is really far away from us. For instance, from Saturn, the Sun will not appear like the brilliant Sun of the Earth, but will look like a very bright star in the sky, which is simply because Saturn is much further away from the Sun than Earth is.
So, to measure the brightness (the scientific term is luminosity) of the star, one needs to know its distance. The main technique to measure the distance to a star is from its parallax (if you want to know as to what it is, please write back). If the star is a variable star (its brightness changes periodically), then one can use the period of the variation to determine the distance to the star.
So, the procedure to measure the brightness is as follows: First, one determines the flux from the star (the rate at which energy reaches us from the star per unit area). This can be done using a CCD camera quite easily. Then, as one knows the distance to the star, one can determine how luminous the star should be to give the required flux.
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
- How does the brightness of a star depend on its distance from us?
- What is apparent magnitude?
- How do astronomers measure the radius of a star?
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 74576 times since April 29, 2002.
Last modified: December 21, 2002 10:23:55 PM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)