First “Christmas Star” In 800 Years Visible on Dec 21st

·2 min read

Skywatchers will be treated to a “once in a lifetime” event on December 21, 2020. In what is known as a Great Conjunction of Jupiter and Saturn, these two planets will be closer in the night sky than at any other point in time since 1623. The conjunction that year was not visible to most of the Earth due to its position in the sky, being too close to the sun to be seen clearly. The last time that a similar conjunction of Jupiter and Saturn was clearly visible to most of the planet was in 1226.

A conjunction happens when planets seem to meet, appearing very close to each other in the night sky. This is because the progress of the planets in their orbits appears to line up from our perspective on Earth. When Jupiter and Saturn meet, it is known as a “Great Conjunction” because these two planets, the largest in our solar system, do not line up as often as the other planets. Great Conjunctions occur every 19.6 years but with varying relative distances between the two planets from our vantage point on Earth. This year they will appear to be just 0.06 degrees apart, whereas the next time they meet in 2040, they will be 1.1 degrees from each other.

With their close proximity, these planets are predicted to appear to the naked eye as a single (and very bright) star, reminiscent of the Star of Bethlehem (Christmas star) described in the Bible as leading the three Wise Men to the town of Bethlehem. Johannes Kepler theorized that a similar conjunction may have been the origin of the Biblical descriptions of that exceptionally bright star. The Christmas star effect is expected to be visible for the entire fourth week of December, but Jupiter and Saturn will be at their brightest on December 21st due to their positions in the sky that night.

Viewed from Alberta, Jupiter and Saturn will be at their brightest roughly 45 minutes after sunset on December 21st and visible to the southwest. If you were to use a telescope or a set of high-powered binoculars, you might even be able to see the largest moons of the two planets in orbit around them. December 21st is also notable for being the winter solstice in the northern hemisphere, the shortest day of the year.

Here’s hoping that we have a clear and beautiful night on this year’s winter solstice.

Dean LaBerge, Local Journalism Initiative Reporter, Grizzly Gazette