is upon us. It’s to be seen in its glory (if weather and the rather low attitude in the sky allow) on the evenings of Sunday Dec. 20 and Monday Dec. 21. Those are just before, and just after, the very closest approach of Jupiter to Saturn. That happens in the daytime between, but on either evening the planets fit into a very small field of view.
I have worked up a full story about this. Please click the “Astronomical Calendar Any-Year” tab at the top and scroll down to the “Conjunctions of Jupiter and Saturn” link.
The story has nine large diagrams and is divided into
“How to see it”
“2020, the year of overtaking”
“Close up”
“The satellites”
“Conjunctions through the centuries”
“Let us know”
__________
Sometimes I make improvements or corrections to a post after piblishing it. If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.
Can you estimate what is the apparent brightness of the two planets together, when they are in their ‘tight formation’ appearing as a single object to the unaided eye? Thanks.
The present apparent magnitudes of Jupiter and Saturn are -2.0 and +0.7. The formula for combining magnitudes (complicated, since they are logarithmic) gives -2.09. In other words, Saturn adds surprisingly little to the total brightness.
Thanks very much, Guy!
Thin clouds (but thick enough) in the south and west for several days running. And at latitude 64.9 North we don’t have much space or time to work with. Still trying.
Low in the south west for me after nightfall which is about 1630 here in north east England at this time of year.Mars and Uranus are much better positioned but not doing anything as exciting as Jupiter and Saturn.
There seems to be an error at the end of the “Close Up” section. Jupiter’s distance is reported as about 150 million kilometers. SkySafari planetarium software says Jupiter is about 900 million kilometers distant.
Also, there’s a formatting glitch in the first paragraph of the “2020, Year of Overtaking” section. Saturn spends about 2 1/2 years in each constellation.
As always, the diagrams are illuminating! I especially enjoy the three-dimensional diagram showing both the heliocentric and geocentric conjunctions.
Steffen Thorsen and Graham Jones’ article on the Sky and Telescope website has a picture of a zodiac chart drawn by Johannes Kepler showing the cycle of Jupiter-Saturn conjunctions during his era:
https://skyandtelescope.org/astronomy-news/the-400-year-rhythm-of-great-conjunctions/
I’ve been enjoying watching Jupiter and Saturn draw nearer to one another, and I’ve been telling friends and passersby (from behind a mask and at a safe distance) about the conjunction. This is a great thing to share with people because you don’t need any special equipment or knowledge to see it.
I made some corrections after the version you opened. Yes, my program gives Jupiter’s distance as 5.93 AU, which is 887,115,373.01 km (depending on how many pseudo-accurate digits you want to discard)!
Where would I need to stand to get that distance accurate to 10 meters? ;-)