The shortest day of the year (for us Northern Hemisphere folk, anyway) is upon us, and, if you are of a denomination which finds it an occasion to celebrate, i hope you find it a good day, whether you're celebrating Koročun, Saturnalia, Yule, or just solstice for solstice’s sake.

Another astronomical event will grace the stars tonight: Jupiter and Saturn are only a tenth of a degree apart in the night sky, closer than they’ve been in 800 years. The best time to view it in the UK (weather permitting) is between 16:30, when the sky starts to darken, and 17:30, when the twins disappear beneath the horizon. Don’t worry if you don’t get to see it tonight; they’ll still be plenty close for the week to come.

Also…

• How Soviet citrologists grew subtropical plants in temperatures as low as 30 °C below freezing
• Navy showers take less than two minutes: Use the first 30 seconds to get wet, shut off the water, lather with soap and shampoo, then rinse for a minute or less
• Bottle tower gardening: that’s one way to make use of your old plastic bottles
• The communist Cookie Monster mural scam