Lunar eclipse set to turn the Moon blood red

The Moon's eclipse will be visible everywhere except Europe, Africa and the Middle East.
NASA Keith Burns

Skywatchers in many parts of the world are set for a treat tomorrow night with a total lunar eclipse. In the US it is a rare second such event in a year. It should be a fabulous sight, clouds permitting, as the Moon turns blood red.

The entire “total” phase of the eclipse will be visible in most parts of Australia, in the US across all but a narrow strip of the East Coast, and parts of Asia including China. (Unfortunately Europe, Africa and the Middle East will miss out this time – but hey! You got to see the Perseids meteor shower earlier this year when we at Cosmos missed out.)

The eclipse begins in the US at 4:15am Central Daylight Time, at different times in Australia from 7:15pm, China at 5:39 and Jakarta at 5:42pm local time (click on the chart below to expand it for a more detailed guide).

Just to refresh your memory, a lunar eclipse occurs when the full Moon passes through Earth’s long shadow. The Moon’s orbit is tilted slightly compared to Earth’s orbit around the Sun, though, so most months the Moon passes a little above or below the shadow. An eclipse occurs only when the geometry is just right.

A blood moon occurs in the event of a total lunar eclipse, when the Sun, Moon and Earth form a line and the Earth blocks all sunlight to the Moon.

The Moon turns a deep red as some light from the sun is bent around Earth's atmosphere and reflected onto the Moon.

On average, there are about two lunar eclipses a year, although not all of them are total and any given spot on Earth will see an average of about one eclipse a year, and all or part of a total eclipse about once every other year. So seeing two total eclipses, as the US is, in one year is rare.

Dr Alan Duffy, an astronomer at Swinburne University of Technology, in Victoria, Australia said there are key aspects of the event to watch.

The eclipse begins with a shadow slowly appearing on the surface of the Moon. Over the next hour more of the Moon will be covered until eventually it lies directly behind the Earth away from the Sun.

At this point the Moon should be blacked-out but it will actually appear blood red. This colour is from all the sunrises and sunsets of Earth shining onto the Moon.

The phase of totality with a red moon lasts for an hour, before the Moon begins to leave the umbra and the series of events reverses over the course of the final hour.

Royal Astronomical Society of Canada

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