Jupiter and Saturn Getting Close and Personal in the SW Sky (H. Michael Mogil, CCM, CBM, NWA-DS*)
While tonight (the planet’s closest encounter as we see it), the two planets will be separated by just 1/10th of a degree in anglular measurement (about 1/5th the width of a full Moon). This tight pairing is merely a line-of-sight effect. In space, Saturn is actually more than 450 million miles behind Jupiter, while Jupiter is some 550 million miles from Earth. That places Saturn at about a billion miles from our Blue Planet.
Planetary conjunctions overall are not rare occurences. However, the conjunction of these two planets is. This “Great Conjunction” puts the planets nearer each other in the sky than they have been for nearly 400 years.
“Witnessing this special event couldn’t be easier,” says Gary Seronik, consulting editor at Sky & Telescope. “On Monday, December 21st, which coincidentally marks the solstice, simply step outdoors roughly 45 minutes after sunset, face southwest, and look about 15° above the horizon — that’s a span slightly greater than the width of your fist seen at arm’s length.” I add that one should be sure that there are no trees and other obstacles blocking your view. Of course, hope that the meteorologists in your area bring clear skies. Folks in the northern tier of states are less fortunate, because the sky show may be too low in the sky for them to witness it.
Also, according to Seronick, don’t wait too long to look for the planetary pair — they set about 2½ hours after the Sun goes down.
When viewing, “you should easily spot Jupiter, the brighter of the two planets,” according to Seronick. “Saturn will be to its upper right, but because Jupiter is more than 10 times brighter and so close to Saturn, the ringed planet might be tricky to spot initially. This is where binoculars come in handy — even with a minimal optical aid, locating Saturn should be easy.
The good news is that “for about 5 days before and after December 21st, the two planets will appear within ½° (one Moon diameter) of each other. This means that if the weather doesn’t cooperate on the 21st, skywatchers will have several other opportunities to see the two planets quite close together.” I saw the two planets nearby about three nights ago. It was a pretty cool sight.
Once Jupiter and Saturn part company this month, they won’t meet up again until 2040. However, that year’s conjunction will be farther apart.
There is also a religious angle to this conjunction. Given the Christmas season, some hypothesize that the so-called Christmas Star actually involved a planetary conjunction. But, as Seronick notes, “there are a lot of dots to connect, not the least of which was when Christ’s birth actually occurred. The date for that is uncertain. Another question is whether or not the “star” was meant to be actual or metaphorical.”
Seronick recommends reading Bob King’s article on the Star & Telescope web site for further details about this conjunction, the Christmas Star, and more. As an added treat, look for a time-lapse video showing how the two planets have approached each other during the last two months.
I just went outside, binoculars in hand, to view the sky show. It was definitely easy to see the brighter Jupiter to the lower left of Saturn. My wife (with better eyesight) saw the two without the need for binoculars.
Just enjoy. It’s definitely a bright spot (on many levels) during a downer 2020.
© 2020 H. Michael Mogil
Originally posted 12/21/20
* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.