Jupiter and Saturn’s ‘Christmas Star’ to light up sky for first time in 800 years

The “once-in-a-lifetime” sighting won’t occur again until 2080 - and then 2400, say experts

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3 December 2020

The two largest planets in our solar system are set to align in a conjuction for the first time in 800 years to create a “Christmas Star”.

Jupiter and Saturn will line up on December 21 and appear to form a double planet - just in time for the festive season.

The Great Conjunction, also nicknamed the “Christmas Star” or “Star of Bethlehem”, hasn't been seen for 800 years.

According to Forbes, a “once-in-a-lifetime” sighting of this proportion won’t occur again until 2080 and then sometime after 2400.

The phenomenon will be visible across the world and enjoyed by die-hard enthusiasts and casual stargazers alike.

When their orbits align every 20 years, Jupiter and Saturn get extremely close to one another.

This occurs because Jupiter orbits the sun every 12 years, while Saturn's orbit takes 30 years — every couple of decades, Saturn is lapped by Jupiter, according to NASA.

Patrick Hartigan, an astronomer at Rice University in Houston, Texas, told Forbes: “Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare because of how close the planets will appear to be to one another.

“You'd have to go all the way back to just before dawn on March 4, 1226, to see a closer alignment between these objects visible in the night sky.

“On the evening of closest approach on December 21, they will look like a double planet, separated by only 1/5th the diameter of the full moon.

“For most telescope viewers, each planet and several of their largest moons will be visible in the same field of view that evening.

“The further north a viewer is, the less time they'll have to catch a glimpse of the conjunction before the planets sink below the horizon.”

NASA says the conjunction will appear “spectacular” with a normal telescope or even the naked eye.

In 1614, German astronomer Johannes Kepler suggested that a conjunction of Jupiter and Saturn may be what was referred to as the “Star of Bethlehem” in the nativity story.

Others have suggested the Three Kings could have been following a triple conjunction of Jupiter, Saturn and Venus or a comet to visit baby Jesus.

Andrew Jacob, of the Sydney Observatory, told ABC that the planets will be so close together that you will be able to see them in one eyepiece of a telescope.

“You would be lucky to see this once in a lifetime,” he said.

Astrophotographer Anthony Wesley also told the publication that he has been observing the two planets from his property in Rubyvale, central Queensland.

“I think they'll actually look at their best just from the naked-eye perspective in the first week of December,” Wesley said.

“They are a little bit higher in the sky and if people are in towns with streetlights you've got just a little bit more chance to see them before they get too low.”

Titan, Saturn's biggest moon, is the second largest in the solar system and the only place outside of Earth where surface liquid has been found.

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Jupiter and Saturn’s ‘Christmas Star’ to light up sky for first time in 800 years

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