Purple Sky’s Majesty

September 10, 2019

Purple sky 082319a

Photographer: Thom Peck
Summary Authors: Thom Peck; Jim Foster

The photo above shows a majestic purple-colored sky as observed over Poway, California, at twilight on August 23, 2019. After sunset, when the Sun is between about 2 to 6 degrees below the horizon, the western sky may take on a noticeable purplish hue. This rather diffuse swath is particularly evident about 45 degrees above where the Sun had just set. Sunlight scattered by the atmosphere is largely responsible for the sunset and twilight colors. However, the purple coloration here is also attributable to aerosols from a recent volcanic eruption, likely from either eastern Russia or Papua New Guinea.

Photo Details: Canon t6i camera; 18mm lens; f/5.6; 1/50 second exposure; ISO 200.