Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Magnitude system

  1. Sep 28, 2005 #1
    I was asked in a problem to guess how Greek astronomers used 2 telescopes (and no CCDs) to determine that stars with magnitudes 1 and 6 differed in brightness by 100x

    My idea was to use different size telescopes to bring the images to the same magnitude in the eyepiec, am i on the right track?
  2. jcsd
  3. Sep 28, 2005 #2


    User Avatar
    Science Advisor

    Not even close.
    (1) Greek astronomers didn't have telescopes.
    (2) The magnitude system of 5 magnitudes being a difference of 100 times in brightness was "decided" on (consensus) in the late 1800's.
  4. Sep 28, 2005 #3
    Sorry, what I meant to say was that Greek astronomers devised the magnitued system and later the astronomer Herschel determined that 2 stars with magnitudes 1 and 6 differend in brightness by 100 times. (My prof gave a hint that he used 2 telescopes to do this)
  5. Sep 28, 2005 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The magnitude system was originally created to be an apparent "brightness" that was determined by eye. Since the eye has a logarithmic response, this eventually translated into the logarithmic brightness system. The magnitudes were assigned long before the system had been formally implemented.

    Yes, though try to be a bit more specific about what you mean by the "size" of the telescopes.
  6. Sep 28, 2005 #5


    User Avatar
    Science Advisor

    Decent explanation can be found here.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Magnitude system
  1. Magnitude Systems (Replies: 1)

  2. Apparent magnitude (Replies: 1)

  3. Apparent Magnitude (Replies: 4)