TODAY! How To Watch the Grand Conjunction of Jupiter and Saturn

"Not the best year" is something we hear after:

a) opening a new bottle of $7 wine at ARSE HQ, or b) describing 2020.

Alas, the year is only going to get better - or worse, if you're into fiction - when Saturn and Jupiter engage in a celestial Tango this Christmas month.

An hour post-sunset tonight, the two gas giants in our solar system will be so close to the eye they'll resemble a singular, shining planet. 

 

Over the past few months, Saturn has been relentlessly hounding Jupiter.

And the ultimate climax will occur just days before the formerly religious holiday turned commercial pursuit for profit named Christmas.

"How rare is this event?" I hear no one ask.

Good question.

 

 

A "grand conjunction" (the meeting of two planets) isn't all that rare, occurring once in about 20 years.

However, Jupiter and Saturn will separate by roughly a 10th of a degree, the closest they've been in nearly 400 years. 

So close that Sydney Observatory curator Andrew Jacob believes you can view them with a single telescopic eyepiece.

"You would be lucky to see this once in a lifetime," The last time a grand conjunction forced the two to overlap was in 1623, and Google images from that time are spotty, at best. 

The next gas giant grand conjunction is in 2080. Which might not be a lifetime away for some, or even 400 years, but the way the world is circling the drain, December's could be the once in a lifetime chance for the entire human race. 

 

 

Although the two planets will seem like they're avoiding social distancing measures, their orbits are separated by a gigantic distance. 

For example, while Saturn orbits the sun in a 30-year cycle, Jupiter takes only 12 years. So Jupiter laps Saturn every two decades. And to us, we watch planets move from east to west across the sky. Tonight's grand conjunction will be no different.

"This is a good chance to see the motions of the sky in action. They're a little bit higher in the sky and if people in towns with streetlights you've got a just a little bit more chance to see them before they get too low" said captain enthusiasm (Andrew Jacob) showing a bit of personality. 

What he's referring to is that while the planet's get closer together, they will eventually get lower as sunsets get later. 

 

 

 

"That will look particularly spectacular both to the unaided eye as well as binoculars and telescopes," says amateur astronomer Dr Ian Musgrave.

Another cool little snippet?

Cover Jupiter and Saturn with your left fist then the moon with the knuckle of your index finger. 

Congratulations!

You're pretty much "Diet Coke Thanos" because you just eradicated (from view) nearly 80% of all the known moons in our solar system. 

You'll block out Pluto too. But since no one cares about Pluto anymore, let's move on.

 

 

On the big day, the two planets will appear over the evening horizon for about half an hour after sunset. You'll have approximately an hour to gorge on the cosmic limbo before they disappear below the western horizon. 

A bit of good news for our northerners; the further north you are, the longer they'll hover in the sky. 

They'll look very close wherever you are, but maximum conjunction happens at 11:33 pm AEST on December 21st. Unfortunately, it would have set below the horizon at this time and slightly sinking out of view in Perth.

 

HOW TO WATCH

The beauty of this conjunction is you can have a look with moderate light pollution and without equipment. 

With the obvious stuff out of the way like weather, look for two bright dots on the western horizon. The smaller dot is Saturn and the larger, brighter dot is Jupiter. 

On December 21st, the two will be so close that they'll appear as one, with no gap between them. Whether you see one or two points depends on the amount of twilight, how close they are to the horizon, and how good your eyesight is. 'The very fact you can look at a dot and say 'that's two separate planets fairly close to each other' is going to be amazing," said Dr Musgrave. 'Out here [central Queensland], there's nothing but dirt and kangaroos so I've got no problems seeing them all the way down to the western horizon," says Anthony Wesley, who has captured highly detailed images of planets. 

Such as the below image of Jupiter's Great Red Spot using a high-speed video camera attached to a 400mm telescope.

 

 

Never fear, you can still have fun with a decent pair of binoculars or a small to medium telescope. You can even see details of Jupiter's four largest moons, Wesley says.

'The innermost moon, Io, only takes three days to do a full orbit. So even just over the space of an hour or two it moves quite noticeably compared to the other moons," he said. With a small to medium telescope, you could see some shapes similar to the below image. You might see Jupiter's two dark bands on either side of its equator or even its iconic red spot if you're lucky. 

"Jupiter only takes about 9 hours 40 mins to do a full rotation, so at some point at one one of those rotations it's facing towards the Earth. There's nothing else like the red spot in the solar system so it's quite a treat to be able to see it," says Wesley. 

There are plenty of apps and online calculators you can use to see when the red spot is facing us. They can even tell you when the gas giants are above the horizon and where. 

You will also be able to make out the rings of Saturn and a few of its moons like Titan.

"The rings on Saturn are at the same size across as Jupiter so even with a moderately small telescope you'll see Saturn and you'll see the rings," Wesley says.

Are you watching?

Tag us in your astrosnaps for a feature! 

#Space_Aus