If you look up in the sky towards the southwest just after sunset, you might notice two bright stars very close to each other in the sky. They are actually our planetary neighbors, Jupiter and Saturn! They will be getting closer and closer together leading up to December 21st, when they will be the closest they have been in our sky since 1623 – almost 400 years ago!
This event is known as a great conjunction, where two planets appear close together in the sky.
However, the great conjunction of 1623 did not occur at night, so it wasn’t visible. It has been almost 800 years, in 1226, since the last time Jupiter and Saturn were this close and actually observable!
How to see this historic conjunction with the naked eye
About 45 minutes after sunset, look towards the southwest above the horizon. You should be able to see two bright objects that look like stars. Saturn is dimmer of the two, slightly above, and the brighter one below is Jupiter.
On December 21st, Jupiter and Saturn will be separated by 0.1 degree in the sky. If you stretch out your arm and hold your hand out in front of you, you can estimate degrees in the sky. The width of your pinky finger is about 1 degree. So, the distance between Jupiter and Saturn will be about 1/10th of that! Here is a good article about measuring distances in the sky.
Please note that in high northern latitudes, the conjunction will not be as visible since Jupiter and Saturn will be too low in the sky.
We suggest checking the weather ahead of time and going outside at sunset or shortly after to make sure you don’t miss this rare celestial event!
The view below shows a preview of what you should be able to see on December 21st and nearby constellations:
How to observe this conjunction using the eVscope
If you want to view Jupiter and Saturn with your eVscope, you should be able to see them in the same field of view (FOV) of your eVscope starting on December 17th.
All you need to do is search for Jupiter or Saturn in the Unistellar app and slew to one of them. Once slewing has finished, move the joystick slightly so the other planet comes into view. As it gets closer to the 21st, you may not have to move the joystick at all to see both planets in the same FOV.
If you lower the gain and exposure, you should be able to make out the rings of Saturn and the cloud bands of Jupiter. If you raise the exposure, you should also be able to even see the four largest moons of Jupiter, called the Galilean moons, and watch as they move their positions over the days leading up to the 21st!
Here is a simulation of the eVscope’s FOV of Saturn and Jupiter on December 18th:
And for the great conjunction on the 21st:
From our CSO and SETI Institute Senior Planetary Astronomer, Franck Marchis: “The conjunction of Jupiter and Saturn is a once in a lifetime event that you don’t want to miss. Though they are actually 456 million miles apart, these two massive planetary bodies will be 0.1 degrees apart from our perspective here on Earth. Since it has been more than 800 years since the last time that this event was visible, we are gifted with a truly remarkable opportunity to observe the wonders of the cosmos and share the experience with the people we cherish most. Even for those of us who are separated from our loved ones in these uncertain times, we can all join together to observe this event, regardless of the distance between, and gaze in wonder at this extraordinary cosmic coincidence.”
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Please send us your images of this historic conjunction and let us know if we can share them!
Clear skies! 🔭