How to watch Jupiter and Saturn’s spectacular ‘great conjunction’

An astronomical conjunction is when any two heavenly bodies appear to pass or meet each other when seen from Earth. In the case of Jupiter and Saturn, the former gas giant takes 12 years to orbit around the sun, while the latter takes a whopping 29 years – that means Jupiter catches up to Saturn every couple of decades, appearing to cross paths when viewed from our lovely blue planet. 

And why is the conjunction between Jupiter and Saturn so 'great'? Simply because they are our solar system's two largest planets. 

This will be first time in 400 years that Saturn and Jupiter pass so close to each other, and the first time in 800 years that it's visible to us.

According to NASA, the two planets will come within 0.1 degrees of each other on December 21 – that's 10 times closer than they usually are. The last time Jupiter and Saturn were this close was in 1623, but sadly our ancestors weren't able to view their heavenly embrace as it occurred right in the sun's glare. That means the last time humans witnessed a conjunction this close was in 1226, when Genghis Khan still roamed the Earth. 

In reality, Jupiter and Saturn will be separated by more than 730 million kilometres of space, of course. But it doesn't stop 2020's great conjunction from being a spectacular, once-in-a-lifetime event. Because to catch the next one, you'd have to wait till 2080 – and we'd rather not wait that long, really. 

You can start viewing Jupiter and Saturn's dance right now! Track their progress daily like a lead-up to the thrilling finale of your favourite drama. 

On December 21 itself, the Science Centre Observatory recommends that you start viewing from 7.30pm onwards. Find an open area with an unobstructed view of the horizon. This could be on a HDB rooftop, carpark rooftop or an open field. Look towards the south-western part of the sky, where the "Christmas Star" formed by Jupiter and Saturn should be visible until about 8.30pm. By then, they would realistically have set behind most buildings and trees in Singapore.  

All you really need are your own pair of eyes. Both planets are bright enough that city lights won't obscure them. Jupiter is said to look like an unblinking star, while Saturn will appear slightly fainter and to the top-left of the other planet. 

For a clearer view, bring along a set of binoculars. Best of all are telescopes of course, with which you'll get an amazing view of the two planets, their largest moons and even Saturn's rings – all visible in the same field of view. 

If standing outside in the chilly night doesn't appeal to you, make sure to keep tabs on the Science Centre Observatory page, where they may livestream the event. Otherwise, head to NASA Science Live to watch the two planets get cosy.