The Stars at Night

Is it really true that the stars seen in a northerner's sky do not seem as numerous and as bright as those in more southerly skies? Since almost everything is better in the Yukon and Alaska, it hurts to admit that our view of the stars is, in fact, inferior.

The reason has nothing to do with the stars themselves. Although the stars are not uniformly distributed in the heavens, the spinning of the earth on its axis exposes to all stargazers similar stellar concentrations through the night. The greatest concentration is seen viewing regions of our own galaxy, the Milky Way. It appears essentially overhead in Alaskan skies, though only about 30 degrees above the horizon at the North Pole.

At high latitudes, the stars do not stand out against the blackness of the sky because the sky there is not black. Even at middle and low latitude the sky is not truly black because of weak luminosity of the high atmosphere. Called airglow, this light emission arises largely from chemical reactions and is about as strong as the integrated, i.e., the total, light from all the stars. Thus at lower latitudes, starlight and the night airglow equally illuminate the earth.

Night airglow typically is brighter at high latitude than at low. Also diffuse auroral glow adds to the light of the night sky. Together the airglow and diffuse auroral emissions provide a rather bright background to view the stars against. In photographic terms, the northern sky scene has reduced contrast compared to the sky farther south. The weakest visual stars cannot be seen, and the brightest stars do not stand out as well.

So even if our stars do not appear as bright and numerous, at least our night skies are brighter than those to the south.