How to watch Saturn and Jupiter's 'great conjunction' in Saskatchewan
Also known as the 'Christmas Star,' the conjunction hasn't been witnessed in 800 years
The "Christmas Star" is visibly returning for the first time since the Middle Ages — and like the three wise men in the Nativity story, Saskatchewan skywatchers will be able to see the astronomical event this month.
What's been popularly called the "Christmas Star" is known to astronomers as a "great conjunction," and occurs when Jupiter and Saturn — our solar system's biggest planets — align in such a way that they appear to merge in our night sky.
Dec. 21 will mark the first time in 800 years that the event will be visible to anyone worldwide. Even in Saskatchewan.
"The planets align every 20 years, but never this close" to each other, said Ron Waldron, president of the Saskatoon Centre of the Royal Astronomical Society of Canada.
This conjunction is the closest between the two planets since 1623, according to NASA — but that conjunction wasn't visible from Earth at night.
Johannes Kepler, a 17th-century German astronomer, calculated these conjunctions back to the first decade BC, which is how the event became linked to the Christmas Star story.
That's where the idea that the Christmas Star was actually a great conjunction comes from, says Daryl Janzen, an astronomy professor at the University of Saskatchewan.
"This one is also occurring around Christmas time," he said, and on the winter solstice.
Where to find the conjunction
The conjunction is actually happening now, but Saturn and Jupiter will appear to align on Dec. 21.
"Everybody should start watching on the 20th and then finish watching it around Christmas Eve. If you do that and get a clear night out of that, you'll see them close together and moving together," Waldron said.
Pick an unobstructed view and look to the horizon at around 5:30 p.m., or right after the sun sets.
"It will be visible as long as you can see right down to the horizon in the southwest," Janzen said. "The further south you go in the province, the better it will be."
Waldron says it's not necessary to leave the city to see the event, but he recommends going to a park in your neighbourhood where there's a clear view of where the sun sets.
Can I see it with the naked eye?
Yes, as long as the sky is clear.
"Jupiter is going to overtake Saturn from our point of view," said Waldron." But this time it is passing so close from our point of view it's going to look like a single planet in the sky, or perhaps an elongated planet, as the two of them appear to merge in the sky."
The 17th-century Italian astronomer Galileo Galilei discovered Jupiter's four moons just before the 1623 conjunction.
"That little telescope he had was basically as good as any binoculars today," said Pierre Schierle, president of the Regina Centre of the Royal Astronomical Society of Canada.
"What you'll want to look for, if you're looking through binoculars on Saturday, is four little dots that will look like stars and will be a straight line. That will be the giveaway that those are the moons."
Jupiter's moon will be clearer if you use a telescope, as will Saturn's rings.
Just about any telescope will do the trick, says Waldron.
"They're very striking planets in a telescope, because Jupiter sports huge bands of clouds in a telescope and Saturn has that gorgeous ring system that takes everybody's breath away," he said.
"So to get the two in one is amazing."