A spectacular double act starring Jupiter and Venus will light up the sky tomorrow night.
The two brightest planets will appear to be unusually close together – roughly two thirds of a full moon’s width apart.
They are not about to collide, it is only an illusion caused by line-of-sight. In fact hundreds of millions of miles of space separate the planets.
After tomorrow they will start to go their separate ways again, with Venus below Jupiter.
David Moore, Editor of Astronomy Ireland magazine, said: "You do not need telescopes to see this 'double planet' but we will be able to show the disks of both worlds in the same field of view, something I have never seen in a lifetime's viewing."
The two planets will be spectacularly close all week, with Monday, Tuesday and Wednesday being the best, and Tuesday night is the very closest.
"We expect this to be the most spectacular sight of the year, even better than the solar eclipse seen in March, and the total eclipse of the Moon due in September, so we are urging everyone to look in the West after sunset," Moore said.
"As these are the brightest objects in the night sky, after the Moon, this event can be seen with the naked eye from anywhere in Ireland.
Venus is now just over 90 million kilometres (around 56 million miles) from Earth and Jupiter almost 900 million kilometres (559 million miles).
Tomorrow night they will appear just 22 minutes of arc apart. For comparison, the full moon is 30 minutes of arc across.
Even a small telescope or a pair of binoculars will show the two planets in the same field of view.
At relatively low magnification Jupiter can be seen as a small circular disc accompanied by four bright moons. Venus will be a fat crescent.
A similar conjunction between the two planets will not be seen again until November 2019.