SKYWATCHERS are getting ready for a colourful astronomical event, with a lunar eclipse due this evening.
The moon will appear to turn cherry red as it enters the lunar eclipse. The event, which will last up to 20 minutes, occurs every two-and-a-half years.
Australian astronomer Dave Reneke said for eastern Australia the eclipse would begin at moonrise, about 5.28pm, when the totality phase would have just started.
At the end of this phase, about 6.25pm, the moon will only be 10 degrees above the horizon, so a higher or ocean vantage point is recommended.
"The further east you are the more of the eclipse you'll see," he said.
A lunar eclipse occurs when the moon passes directly behind the Earth into its shadow.
This can occur only when the sun, Earth and moon are aligned exactly, or very closely so, with the Earth in the middle.
Unlike a solar eclipse, which should never be looked at directly, it is quite safe to look at a lunar eclipse.
In fact, the light of the moon will actually be dimmer than normal.
Those watching will see light slowly disappear from the moon as the earth moves in front of the sun.
Then, at the peak, they'll see a vague, ghostly disc rather than the bright shining one usually seen.
The same night of the lunar eclipse will be one of the nights when the planet Mars is closest to the Earth.
"The Red Planet is getting closer to Earth in its journey around the Sun," Mr Reneke said.
"Look for a brilliant reddish 'star' in the south-eastern sky. That's Mars, and it even outshines Sirius.
"By the time you finish reading this story, you'll be about 1000km closer to Mars."
Mr Reneke said the distance between the two planets was shrinking by about 300km every minute.
"On April 14, the distance between Earth and Mars narrows to only 92 million kilometres, a small number on the vast scale of the solar system, but a seven month flight for NASA's speediest rockets," he said.
"Mars will be easy to see with the unaided eye, even from brightly lit cities.
"With a modest backyard telescope, you can view the rusty disc of Mars as well as the planet's whitish north polar cap.
"From Mars, the sun appears only 44% as bright as it does from Earth."
- A lunar eclipse can only occur the night of a full moon
- A lunar eclipse may be viewed from anywhere on the night side of the Earth
- More details at the Sydney Observatory website