Quote:
Originally Posted by Nyah
This one is supposedly going to be visible for a couple of months, and at some points they're predicting it'll be brighter than the Moon. Can't wait!
|
When they say "brighter than the moon," they're referring to total brightness, not surface brightness. That is to say, a comet's tail may cover tens of degrees of the sky, whereas the moon is concentrated in a circle half a degree in diameter. The total light you get from both can be the same, but one looks a whole lot brighter than the other.
Comet McNaught (the 2007 one) may have had an overall brightness greater than that of Venus, but comparing the two side-by-side you would still have said Venus was brighter. That said, it was pretty awesome to see a naked-eye comet in twilight that year.