skysurfer
25-12-2017, 03:26 AM
Many textbooks, internet sites tell that e.g. Betelgeuse is red, Canopus is 'yellowish white', but what are the actual colors ?
It depends on the circumstances, how high is the object in the sky or even the observer.
When a star is low in the sky (< 10 degrees) the object turns redder, which is also the case with hazy air.
For example, the 'yellowish white' Canopus appears bluish white for me and 'white' Deneb just bluish white. Capella or Alpha Centauri appear indeed yellowish white to me, but in daylight more than at night. In daylight it is possibly the contrast to the blue sky background.
But the (much brighter) Sun appears just plain white.
What are your opinions ?
It depends on the circumstances, how high is the object in the sky or even the observer.
When a star is low in the sky (< 10 degrees) the object turns redder, which is also the case with hazy air.
For example, the 'yellowish white' Canopus appears bluish white for me and 'white' Deneb just bluish white. Capella or Alpha Centauri appear indeed yellowish white to me, but in daylight more than at night. In daylight it is possibly the contrast to the blue sky background.
But the (much brighter) Sun appears just plain white.
What are your opinions ?