Jupiter and Saturn to align in December to create 'Christmas Star' for first time in 800 years
For the first time in nearly 800 years, Jupiter and Saturn will align in the winter solstice sky to become what is known as the "Christmas Star" on Dec. 21.
The last time this rare celestial event, called the "great conjunction," was observable was March 4, 1226. The gas giants closely aligned in 1623, but its proximity to sunset made its visibility unlikely, according to EarthSky.
Jupiter and Saturn meet every 20 years, but on Dec. 21 they will be just 0.1° apart — 1/5 of a full moon diameter. The next time the conjunction will occur at a distance this close will be on March 15, 2080.
The conjunction will create a brilliant point of light called the "Christmas Star" or "Star of Bethlehem," capping 2020 off with a celestial Christmas.
How you can see the 'Great Conjunction'
You can see Jupiter and Saturn appear to collide in the night sky anywhere on Earth as long as skies are clear. On Dec. 21, look to the southwest after sunset. The planets will be visible and appear low in the western sky in the northern hemisphere for about 45 minutes to an hour after sunset.
But you don't have to wait until Dec. 21 to see the astronomical conjunction. Jupiter and Saturn are gradually getting closer and closer every day. According to Space.com:
- Nov. 1: 5.1° apart
- Nov. 15: 3.8° apart
- Dec. 1: 2.2° apart
- Dec. 15: 0.7° apart
- And then 0.1° closer every night until Dec. 21
Why it's rare for Jupiter and Saturn to align so closely
Saturn is the farthest and slowest-moving planet in the solar system that is visible to the naked eye, according to EarthSky. Jupiter is next.
It takes Saturn 30 years to orbit around the sun while it takes Jupiter 12 years. Their slow movements around the sun make their conjunction such a rare occurrence.
Here is a timeline of conjunctions between Jupiter and Saturn, according to EarthSky:
- May 28, 2000
- Dec. 21, 2020
- Oct. 31, 2040
- April 7, 2060
- March 15, 2080
- Sept. 18, 2100
Astrology.com says the event symbolizes 'new growth'
The "great conjunction" is the leading way to mark historical eras in traditional astrology since it occurs every 20 years, according to Astrology.com.
The cosmic guidance website says Jupiter and Saturn coming together brings "both the intensity of old forms dying as well as the fertility of new growth beginning to take shape."
It also combines the "expansive and imaginative vision with the structure and discipline needed to both manifest results as well as strip away the inessential", according to Astrology.com.
Daniella Medina is a digital producer for the USA TODAY Network. Follow her on Twitter @danimedinanews.