Tonight, they kiss. Jupiter and Saturn, in reality, are as close to kissing as Hilary Clinton and Donald Trump. Today, the Winter solstice (in the Northern hemisphere), Saturn is twice as far from Earth as Jupiter. Jupiter is 886 million km (551 million miles) from Earth and Saturn is 1.6 billion km from Earth. They just look close because of the power of perspective.
This is more than just a once-in-a-lifetime opportunity. The last time Jupiter and Saturn were this close was in 1623 (but probably nobody saw them because of the angle they were at). And the last time a great conjunction occurred that was as easy to see as this year’s was in 1226.
In the photos below, the larger, brighter planet is Jupiter. I saw the forecast for today and went to Parliament Hill yesterday to see the planets. There were many other people there, often asking what we were looking at! At about 3.45pm, the planets were visible in the bright sky. As it got darker, the clouds appeared. And just when we thought we wouldn’t see the planets in the night sky, the clouds cleared. The stars shone. Even Mars was visible.
Jupiter and Saturn are gas giants. They mostly consist of hydrogen and helium. Therefore, if you tried, you couldn’t actually stand on them. What we see are gases on the outside. So if you stepped on the planet, you would sink down and be crushed by the pressure inside the planet.
On Jupiter, the gravity is two-and-half times that on Earth. If you weigh 63 kg (10 stone), you would weigh 157 kg (almost 25 stones) on Jupiter! That is extreme weight gain and another reason you should be hesitant about visiting Jupiter.
Some scientists think that the Star of Bethlehem was not a star at all but rather a previous coming together of Jupiter and Saturn. In Roman mythology, Jupiter was the king of the gods, having replaced Saturn in a friendly cosmological takeover. They believed some of the planets looked after them. We could all do with a bit of looking after at the moment. Let’s hope the coming together is a sign of better times. Or maybe it’s just a cosmological event.