Sky Matters: Look to the skies for Jupiter and Saturn optical illusion

The apparent closeness of Jupiter and Saturn will be an optical illusion resulting from Jupiter passing in front of Saturn

Jupiter and Saturn will be as close in the sky as they last were during the Norman invasion of Ireland.

December skies are often good for skywatchers. The nights continue to get longer, offering the possibility to observe stars and planets from well before teatime and right up until breakfast. It’s a great month to introduce the kids to the skies above. Happily, this December there are a number of celestial wonders gracing our skies for us all to enjoy. Venus rises in the south-eastern sky about 5am and is visible until it gets lost in the glare of the morning Sun around 7:30am. The planet drifts closer to the Sun as the month progresses but will be visible throughout the festive period. During 2020 we learned that Venus may harbour life, a prospect that makes it all the more enticing to view.

A few days previous to the Big Day, on December 21st, we have the winter solstice when the length of day falls to its shortest – a meager 7 hours and 30 minutes. Of course, every cloud has a silver lining and on this December 21 we have a rare “conjunction” of Jupiter and Saturn in which the two planets will be so close in the sky as to look like a bright double planet. This is the closest these two giants of the solar system will appear to have been in over 800 years – the last time such a close conjunction occurred was during the Norman invasions.