It’s no secret that 2020 has been different from many other years. So too from an astronomical standpoint. 

This December, Jupiter and Saturn will have the closest visible alignment in 800 years for a celestial event that is known as a “great conjunction.” For most people, this is a once in a lifetime opportunity to see a conjunction between the two biggest planets in our solar system.

Though a great conjunction happens about every 20 years, the last known occurrence of a conjunction this close was in  1226, which occurred 14 years after Galileo built his first telescope. This means this will be the closest visible encounter between the two giants since the Middle Ages.  The conjunction was 13 degrees away from the sun, making it practically impossible to see from Earth, according to Amy C, Oliver, a spokeswoman for the Center for Astrophysics, Harvard & Smithsonian.

The conjunction is the result of the orbital paths of Jupiter and Saturn coming into alignment, as viewed from Earth. Jupiter orbits the sun about every 12 years, and Saturn about every 29 years. Although Jupiter and Saturn seem close, they will be more than 400 million miles apart. Because the planet’s orbital paths intersect, If you wait long enough, the conjunction is bound to happen. However, this doesn’t happen too often. 

During the first 3 weeks of December, we have watched and continue to watch as Jupiter and Saturn get closer to the sky than they’ve appeared in 2 decades. According to NASA, on December 21st, the two gas giants will be seen a tenth of a degree apart, which is about the thickness of a dime held at arm’s length. This means that Jupiter and Saturn and their moons will be visible in the same field of view through binoculars or a small telescope. Saturn will look as close to Jupiter as a few of Jupiter’s moons! This is the “greatest” great conjunction between Jupiter and Saturn for the next 60 years. The two planets will not appear this close in our night sky until 2080, so make sure to try to get a glimpse at this rare event.

How can we see it? Although best appreciated with binoculars or a telescope, the encounter should be visible to the naked eye. The planets will be so close, they will appear, from some perspectives, to overlap completely, creating a rare “double planet” effect. The great conjunction will be shining bright shortly after sunset, low in the southwestern sky, as viewed from the Northern hemisphere. Saturn will appear just to the east of Jupiter. The event is observable from anywhere on Earth, provided the sky is clear. The Planets are close throughout December, however Monday, December 21st is the day to look up! The earlier the better – don’t miss out on this once in a lifetime, chance to see a rare alignment!