Why is it called the Great Conjunction or the Christmas Star?
Some refer to the significant event as “The Christmas Star” while scientists call it the great conjunction of Jupiter and Saturn, the two huge gas planets. What everyone can agree on is that it’s a magnificent sight to behold in our night sky. Jupiter and Saturn haven’t strayed too far from each other, but on this night they are closer than they’ve been in 400 years.
A conjunction is when two objects appear at a close distance from earth. When referring to Jupiter and Saturn’s meeting, it’s called a Great Conjunction. The reason it doesn’t happen more between the two is because of their incredibly slow rotation. Jupiter takes 12 years to do a complete trip around the sun while Saturn takes 29.5 years. As a result, their conjunction only happens every 20 years, but to get as close as they will on Dec 21 takes over 400 years.
We also refer to the Great Conjunction as “The Christmas Star.” Jupiter and Saturn already appear as two bright stars in our night sky, but on this night they will appear as one. Even though they won’t stay the closest distance but, they will appear as one dazzling star till close to Christmas for our enjoyment. Another fun fact is that in 7 B.C. there were three conjunctions for Saturn and Jupiter, which can be seen as a replica of the Sar of Bethlehem hence another way it gets the name the “Christmas Star.”
History of Great Conjunction
The last time Jupiter and Saturn appeared so close was on July 16, 1623, but this Christmas star wasn’t observable. The reason for this was that the planets were 13 degrees east of the Sun. The last observable Great Conjunction of this distance took place on March 4, 1226. While the two planets are actually 735 million miles apart visually, they will appear to be.5 degrees from one another. The only other two planets to appear to come this close were Mars and Saturn on June 5, 1978.
When to Watch for Christmas Star
On December 21, 2020, an hour after sunset looks to the southwest sky. You will easily see Jupiter as a sparkling star. Saturn will appear a bit dimmer and positioned above and to the left of Jupiter. During the conjunction, the two will appear as one amazingly bright Christmas star. The only way to see them as two separate bodies is through and a telescope or through a pair of binoculars. After the conjunction when they appear as one, Jupiter will pass Saturn and reverse positioning in the sky. Don’t miss this spectacular event because it will be the last until March 15, 2080. They will squeeze even tighter together on Christmas of 2874.