Most people would probably consider a sky filled with twinkling stars to be the perfect setting for the observational astronomer. However, such a sight is perhaps the worst scenario for viewing the sky.

As the beam of light from a star passes through the air, it is refracted, or bent, irregularly while passing through varying pockets of air, with the resultant effect of scintillation.

If you tried observing with a telescope on such a night, you'd be very disappointed. Looking at a particular star or planet through such a turbulent atmosphere, the image would appear to constantly dance, or shimmer, even if you were using a low power eyepiece.

Nights of poor "seeing," as astronomers call it, are usually encountered immediately after the passage of a storm or a sharp weather front. It is better to wait at least 24 to perhaps 48 hours after such a weather system has moved on by, to allow the local atmosphere to calm-down and allow steadier views.

Ironically, summer nights that appear rather hazy and with fewer stars often yield the best telescopic views. While not as transparent or pristine as cold, crisp winter nights, the atmosphere is usually much steadier.