Aug. 23, 2012 -- It's that time of year again, when the realization suddenly hits that the sun is setting earlier than it was just last week. In just another month, the long days of summer will be gone in the Northern Hemisphere and just beginning in the Southern.
But it's undeniable that twilight, that quarter hour just before the sun ducks under the horizon, can create some of the most beautiful light on Earth.
Absorb the twilight around the world in this slide show of breathtaking images at dusk.
Twilight, Gusev Crater, Mars
The Mars rover Spirit took this sunset image in April 2005 at Gusev Crater, on the Red Planet.
Lightning on an Open Highway
Lightning strikes a remote highway at dusk.
Whether geese are migrating to or from your area, there's nothing that quite evokes fall like their honking.
The sun sets on Tokyo as the city's lights go on.
An Indian woman in traditional clothing holds her daughter in the fading sunlight.
This the mysterious stone figure is called an inuksuit, meaning "in the likeness of a human" in the Inuit language. This inuksuit dwells in purple along Lake Winnipeg, Manitoba, Canada.
Space Shuttle Atlantis stood on Launch Pad 39A for the final time in history in July, 2011, bathed in light and rain.
The early-evening moon lights the path of this canoer on Lyme Regis.
Golden twilight suffuses the grasslands in Kenya.
Fall colors will soon follow shorter days for those of us in the Northern Hemisphere.
Workers head home, or to meet up with friends, in Tokyo, Shinjuku District, Kabukicho entertainment area.
Geese settle down for the night on the banks of the Rhine.
Japan, Mt. Fuji
Swans head for their evening spot as twilight envelops Mt. Fuji.
Dusk drops its cloak over the sea at Los Lances, Cadiz, in Andalusia.