The planets Jupiter and Saturn are set to “meet” in the sky on Monday December 21 in a phenomenon that only occurs once every 20 years. The event is expected to be visible from France, weather dependent...
The event is set to occur at around 19:22 French time. At this time, the two planets - the largest in our solar system - will “appear as one planet” and be perfectly aligned.
This phenomenon, known as the “great conjunction”, only happens once every 20 years. Space news service Space.com has also called it "the Christmas star".
And, in 2020, the event will happen “at a very minimal distance in the sky”, Florent Deleflie, an astronomer at the Paris Observatory, told news source FranceInfo. The last time it happened at such a distance was in 1623.
Mr Deleflie said: “We will be able to see everything, the equatorial rings of Jupiter and its main satellites, and the rings of Saturn. It will be spectacular.”
“In reality, these planets will obviously stay a good distance away from each other”, he added.
Jupiter is 775 million kilometres from Earth, while Saturn is even further away, at 1.4 billion kilometres on average.
TOMORROW Jupiter and Saturn will be at their closest separation in the sky since 1623 at 0.1° apart. Here's an animation showing exactly how close that is relative to a familiar object, the Moon! (Moon ONLY added to illustrate the scale) #GreatConjunction2020 pic.twitter.com/2mvdl6KjmI— Dr. James O'Donoghue (@physicsJ) December 20, 2020
Tips for skygazers
Mr Deleflie had this advice for people hoping to catch the best view of the phenomenon.
He said: “Obviously, the further away you go from urban lights, the better it is. But [if not] Jupiter and Saturn are planets that are bright enough to be seen from very well-lit areas.”
He also suggested:
- Start looking at soon as night falls, and look towards the south-west
- Try to find a wide horizon with a clear view
- Pray for good weather
- Seek out an astronomy club (a list can be found here on the Association Française d’Astronomie website)
On the subject of good weather, forecaster Météo France has so far predicted relatively clear skies across the south, south-west and French-Spanish border.
Across the rest of the country more clouds and rain are unfortunately expected.