Just in time for Christmas week, a “Christmas Star” will appear in our sky. It won’t actually be a star, but instead two planets coming very close together in our sky.
It’s a cosmic connection not seen in 800 years. The Great Conjunction takes place on Dec. 21.
“When you look up in the sky with the naked eye, you’re going to see two star-like objects that are almost touching each other,” Scott MacNeill said with his hands pointed upward to the sky in front of Brown University’s Ladd Observatory in Providence.
They won’t be stars, but instead two gas giant planets, Jupiter and Saturn. From our perspective, they will appear to be very close.
“Jupiter’s got about a 12 year orbit around the sun, Saturn’s got a 30 year orbit. So Jupiter will overtake Saturn every 12 years, but viewing it from Earth we’ll see it about once every 20 years because of Saturn moving as well,” MacNeill, the director of the Frosty Drew Observatory in Charlestown said.
Although they will look close to us, they will be more than 450 millions miles apart.
“But if you take our distance from Jupiter, that’s actually how far Jupiter is from Saturn, when they’re all in a line like that,” MacNeill said.
For years, historians and astronomers have attempted to understand what the “Star of Bethlehem” was. The Three Wise Men followed the star from Babylonia to Bethlehem for a journey which would have taken months. A comet was probably an unlikely source of the bright light as comets were thought portend evil or doom. An exploding star from a distant point in the galaxy has been another theory. Planetary conjunctions, however, seem to be the most likely reason for the original Christmas Star as there were a number conjunctions during the period 7 to 4 BC.
Fast forward 2,020 years, and we now know that these bright points of light are just two planets passing in the night, which is a mere coincidence.
So a conjunction like this one is not too rare, but the two planets have not been this close together in our sky since the Middle Ages!
To see the cosmic lineup, just look to the west-southwest sky between 4-6 p.m. Weather-permitting, you’ll be able to see the two planets close together. A telescope, however, will give an amazing view.
“In a telescope, you’ll be able to see Saturn’s rings, Jupiter’s equatorial bands and all their moons together in the eyepiece,” MacNeill said.
If the weather doesn’t cooperate, or if you miss it, they’ll still be fairly close together on Dec. 22 and the days following…just not quite as close as on the 21st.
“And we don’t see them this close again until 2080,” MacNeill said.
The Frosty Drew Observatory in Charlestown will host an in-person event on Dec. 21 to a limited number of people.
You will need tickets in advance to attend. The observatory will also host a livestream of the event as well.