Is there a problem?

Finally I come to a book that says, "Mathematics is used in science in many ways. We will give you an example from astronomy, which is the science of stars." I turn the page, and it says, "Red stars have a temperature of four thousand degrees, yellow stars have a temperature of five thousand degrees . . ." -- so far, so good. It continues: "Green stars have a temperature of seven thousand degrees, blue stars have a temperature of ten thousand degrees, and violet stars have a temperature of . . . (some big number)." There are no green or violet stars, but the figures for the others are roughly correct. It's vaguely right -- but already, trouble! That's the way everything was: Everything was written by somebody who didn't know what the hell he was talking about, so it was a little bit wrong, always! And how we are going to teach well by using books written by people who don't quite understand what they're talking about, I cannot understand. I don't know why, but the books are lousy; UNIVERSALLY LOUSY!

Richard Feynman (1997, p.293), annoyed by a textbook discussing green stars.

Contents

• 1 Why stars are not green
• 2 Objects that resemble green stars
  • 2.1 Multiple stars
  • 2.2 Nebulae
  • 2.3 Beta Librae (Zubeneschamali)
  • 2.4 Uranus
  • 2.5 The Sun
  • 2.6 False color images
  • 2.7 Flying objects
• 3 References
• 4 See also
• 5 External links

Why stars are not green