By Liam Mannix
Get set for a once-in-a-lifetime astronomical event on Saturday morning. It's worth getting up early for.
About 4.30am, before sunrise, a shadow will start to creep across the moon. Bite by bite, the white orb will be consumed in shadow – and appear to turn a dark, blood red.
The blood moon, seen over Melbourne in 2014.Credit: Darrian Traynor
And glimmering nearby, above and a little to the left, will be a yellowish-red dot. Mars, the closest it has been since 2003.
The last time these two events, a total lunar eclipse and the opposition of Mars, lined up was in the year 792. It won't occur again for hundreds of years, says Sydney Observatory's curator Dr Andrew Jacob.
Mars's orbit is longer than Earth's, meaning it has further to travel to loop around the sun. Every so often the Earth's orbit catches up with Mars, bringing the two planets nearer. This time, they will close to within just 58 million kilometres.
Earth will also be directly between the sun and Mars. This event, known as an opposition, will make the planet appear even brighter.
Until September Mars will be the third-brightest object in the night sky behind the moon and Venus.
It will look spectacular with binoculars or just the naked eye, astronomers say.
With a telescope, an observer would be able to clearly see features on the planet’s surface including the polar ice caps. If there wasn't a huge dust storm.
"Right now a global dust storm on Mars is concealing all its features. We hope the dust will settle and clear over the next few weeks to reveal the surface of Mars," says Dr Jacob. “At the moment it looks like a fairly featureless yellow disc.”
Meanwhile at 4.24am Saturday morning the moon's orbit will start to take it behind the Earth, casting the moon into shadow.
“Anyone looking toward the western sky will see a bite begin to be taken out of the moon. Over the course of the next hour, the moon will go darker and darker as it is eclipsed by earth’s shadow,” says Dr Jacob.
By about 5.30am, the moon will be totally eclipsed.
The eclipse will last one hour and 43 minutes. But the moon won’t vanish from sight but will turn a deep blood red.
That’s because some light from the sun will pass around the sides of the Earth and shine onto the moon. Our atmosphere filters out all the colours of the light, except red.
The Astronomical Society of Victoria are hosting several viewing parties around Melbourne where members of the public can view Mars through portable telescopes (you won't need any help seeing the eclipse). On Friday at 8pm they'll be out at Braeside Park, and on Sunday at 8pm they'll be set up at Royal Park in Parkville.
Hundreds will also gather at the Sydney Observatory’s green grounds on Millers Point to use its twin telescopes to take in first the opposition of Mars, and then the red moon of a total lunar eclipse. Sadly, the event has already sold out.