LOS ANGELES: The longest partial lunar eclipse in nearly 600 years, which bathed the Moon in red, was visible for a big slice of humanity on Friday.

The celestial show saw the lunar disc almost completely cast in shadow as it moved behind the Earth, reddening 99 per cent of its face.

The spectacle was visible for all of North America and parts of South America from 0602 GMT on Friday, and was later seen in Australia and northeast Asia.

By 0750 GMT, sky-watchers with a cloud-free view in those regions saw the Moon half covered by the Earth’s penumbra — the outer shadow.

Space scientists said on Thursday that by 0845 GMT the Moon would appear red, with the most vivid colouring visible at peak eclipse 18 minutes later.

The dramatic red is caused by a phenomenon known as “Rayleigh scattering”, where the shorter blue light-waves from the Sun are dispersed by particles in the Earth’s atmosphere. Red light-waves, which are longer, pass easily through these particles.

“The more dust or clouds in Earth’s atmosphere during the eclipse, the redder the Moon will appear,” a NASA website explained. “It’s as if all the world’s sunrises and sunsets are projected onto the Moon.”

From the moment the eclipse began — when the Moon entered the Earth’s shadow — to when it ended took more than three hours and 28 minutes.

That is the longest partial eclipse since 1440 — around the time Johannes Gutenberg invented his printing press — and won’t be beaten until the far-off future of 2669.

But Moon watchers won’t have to wait that long for another show — there will be a longer total lunar eclipse on November 8 next year, according to NASA.

Even better news for anyone wanting to watch was that no special equipment was necessary, unlike for solar eclipses. Binoculars, telescopes or the naked eye gave a decent view of the spectacle — as long as there was good weather.