The longest "blood moon" eclipse this century began on Friday, coinciding with Mars' closest approach in 15 years to treat skygazers across the globe to a thrilling celestial spectacle.

Unlike with a solar eclipse, viewers do not need protective eye gear to observe the rare display.
"All you have to do is... go outside!" the Royal Astronomical Society (RAS) in London said, adding that binoculars would be useful to observe the phenomenon.

For about half the world, the moon will be partly or fully in Earth's shadow from 1714 to 2328 GMT -- six hours and 14 minutes in all.

The period of complete eclipse -- known as "totality", when the moon appears darkest -- will last from 1930 to 2113 GMT. At the same time, Mars will hover near the moon in the night sky, easily visible to the naked eye.