On April 12th, 1961, Soviet cosmonaut Yuri Alexseyevich Gagarin became the first human in space. His remotely controlled Vostok 1 spacecraft lofted him to an altitude of 200 miles and carried him once around planet Earth. Commenting on the first view from space he reported, "The sky is very dark; the Earth is bluish.

Have you seen an Iridium flare? Satellites in low Earth orbit reflect sunlight and are often visible gliding across early evening and predawn skies. But sun glints from Iridium commercial digital communications satellites are providing the most spectacular sightings.

In low Earth orbit there is not enough atmosphere to diffuse and scatter sunlight, so shadows are black and the sky is dark - even when the Sun shines. The harsh lighting produced this dramatic...