Sydney is in the box seat to watch a rare astronomical threesome.
On Wednesday evening the International Space Station will pass close to Venus and Jupiter in the north-western sky, as viewed from Earth.
At 5:31pm AEST, the ISS, which looks like a fairly bright, moving star, will appear low in the north-western horizon. It will rise and pass Jupiter first and then journey past Venus at 5:34pm.
The space station will take only seven minutes to cross from one horizon to the other.
Geoff Wyatt, the acting manager of the Sydney Observatory, said the space station circles the Earth every 90 minutes but this is likely the first time it will appear so close to these two planets since it was launched in 1998.
"It's a nice happenstance for all three objects to be so close together," he said.
Venus and Jupiter have been the brightest objects other than the moon in the night sky for more than a month, and were closest to each other on Wednesday last week.
Venus is always bright because it is close and covered in cloud that is very reflective, said Mr Wyatt. Jupiter is also bright because it is cloudy but it is a lot further away. The two planets' orbits have aligned so that they appear close together, seen from Earth
"People have been calling us on a daily basis asking what are the two very bright objects," he said.
"But tomorrow night is going to be really quite spectacular."
While other parts of the country will be see all three objects, they'll appear closest to each other from Sydney.
Mr Wyatt said while the night sky is typically clear at this time of year, if clouds threaten his view, he'll head to the Blue Mountains.
"This is too good an opportunity to pass up," he said.
To create a star chart where you are, visit heavens-above.
