Skygazers with a clear view in North America and Europe were greeted with a celestial treat in the early morning hours Tuesday, as a unique total lunar eclipse was to transform the Moon pink, coppery or even a blood red.
Coinciding eerily with the northern hemisphere's mid-winter solstice -- for the first time in almost four centuries -- the eclipse began showing the Sun, the Earth and its satellite as they directly aligned, with the Moon swinging into the cone of shadow cast by its mother planet.
Despite being in shadow, the Moon did not become invisible, though, as there is still residual light that is deflected towards it by our atmosphere.
Most of this refracted light is in the red part of the spectrum and as a result the Moon, seen from Earth, turns a reddish, coppery or orange hue, sometimes even brownish.
NASA's veteran eclipse expert Fred Espenak explained that while the entire event was to be visible from North America, Greenland and Iceland, western Europe sees the beginning stages before moonset and western Asia gets the later stages after moonrise.
The eclipse was to run for three and a half hours, from 0633 GMT to 1001 GMT, although the stage of total eclipse -- when the Moon heads into the "umbra" cast by the Earth -- lasts from 0741 to 0853 GMT.
Two factors affect an eclipse's colour and brightness, said the US astronomy magazine Sky & Telescope.
"The first is simply how deeply the Moon goes into the umbra. The center of the umbra is much darker than its edges," it says.
"The other factor is the state of Earth's atmosphere along the sunrise-sunset line. If the air is very clear, the eclipse is bright. But if a major volcanic eruption has polluted the stratosphere with thin haze, the eclipse will be dark red, ashen gray, or blood-black."