Don't miss the transit of Venus
"IT'S just a cool thing."
That was Brad Tucker, research astronomer with the Mount Stromlo Observatory in Canberra, describing the transit of Venus.
He said the twice-in-120-year phenomenon was one of only a few astronomical events that could be seen with the naked eye.
"The great thing about the transit of Venus, for me, is that there's a multitude of astronomical events that go on that you can only see with telescopes or at the observatory.
"While you shouldn't look directly at the sun, you can do things like reflect the image onto something, and you can see Venus travelling past the Sun.
"From an astronomical perspective, the transit happens twice every 120 years.
"They come in pairs, so we had one in 2004 and then today's - but the next one won't be until 2117 with its pair in 2125.
"One of the biggest things I think is great about the transit is that Venus is about the same size as Earth.
"It is a little bit smaller, but seeing that in comparison to the Sun - it really puts things in perspective."
Mr Tucker said the transit of Venus was a unique event where astronomers around the world had a chance to measure the distance between Earth and the Sun.
"We can use very simple trigonometry to measure these distances, and so we can calculate that.
"From what we understand, the orbit of the Earth is slowly changing, and the size of the Sun is also changing.
"So if we keep taking this measurement another 20 times or so, we will start to get an idea of how much the Earth's orbit is changing.
"Of course, that would take thousands of years to record only a small change, but we can do it."
To see the transit of Venus safely, readers can use a pinhole projector, eclipse glasses, or project a magnified image of the transit using a reflector telescope.
While the transit can be seen without the aid of telescopes, do not look directly at the sun as it can cause irreversible damage to the eye.
Past transits of Venus:
- 1874 and 1882
- 1761 and 1769
- 1639 (first known observation).