400° Early Twilight
At Stockholm, Sweden by Peter RosÚn.

"I was up on my rooftop on the 27th of August and just enjoyed the evening sky view. For living in a capital I enjoy a quite unique unobstructed 360° view of the sky.  The sun was well below the horizon when suddenly there was a magnificent display of crepuscular rays that lasted only for some minutes. At the same time the earth’s shadow was high in the east and the typical pink anti-twilight arch had already faded away.   I had just time to take 4 pictures in the 90° apart with a Canon fisheye zoom 8-15 / f4 set at 8 mm (full circular fisheye) on a Canon Eos5D MkII and stitched them together for a 400° view."    ©Peter RosÚn, shown with permission

The sun was 3.8° below the horizon. Above it the sky glows with a band of red to yellowish light, sunlight scattered forwards by the atmosphere - the twilight arch.   

From NE to South the dark mass of the
shadow of the Earth looms above the horizon.

Above it (but not visible here because the shadow edge becomes more diffuse as the sun sinks more than 3° below the horizon) we often see a rosy pink band. This is the
anti-twilight arch or 'Belt of Venus'. The band arises from a combination of purple skylight and backscattered and reddened sun rays.

As the sun sinks lower than 4 to 6° look 45° above the sunset point for a purple glow ~20° wide - the
purple light. The glow is quite variable in intensity and is thought to be from light scattered by dust in the stratosphere. It is not properly understood.

Twilight is a magical time.
Atmospheric
Optics

About - Submit Optics Picture of the Day Galleries Previous Next Today Subscribe to Features on RSS Feed
        

        

Earth shadow and Belt of Venus formation.