Tilt

Winter solstice comes on Friday December 22 at 3:28 by Universal Time. Or, more accurately, the December solstice: it’s the moment when Earth’s north pole is maximally tilted away from the Sun–

–as shown in one of the illustrations in the four-page “Sun and Seasons” section of Astronomical Calendar 2023, where there is much more about the meaning and implications of the solstices and equinoxes, and the Sun’s movement through the constellations.

Here again is the sky scene we used a couple of days ago to show asteroid Vesta at opposition.

The “anti-Sun”, or direction opposite to the Sun, coincides with the northern solar solstice point, or northernmost point on the ecliptic or path of the Sun.

Home planet department

Tilt: it means to lean from a vertical to a slanting attitude, but in the Middle Ages it was applied to the sports at a joust or tournament. Knights on horseback tilted: leaning forward in their saddles, they charged at and past each other, trying, with their lances, to unseat each other. It was a way of impressing the ladies. They also “tiled at the [suspended] ring” or “rode at the ring” to practise accuracy. “The bonnie Earl of Murray, / He rid at the ring, / And the bonnie Earl of Murray, / He micht hae been a king.”

And we were going to say a bit more about Vesta, virgin goddess of the hearth and home. Her Greek counterpart, Hestia, was the eldest of the twelve Olympians.

In this family tree from the “Planets” section of the Astronomical Companion, the row of six in the older generation should be rearranged with Hestia, the first-born, on the left, and Zeus on the right (but it would have made the diagram inconveniently wider).

The Vestal virgins were chosen as children to become priestesses, confined in Rome’s temple of Vesta for at least thirty years, during which they had to maintain their vows of chastity and keep the flame in the temple alight. They risked harsh punishment if they failed in either of these, but otherwise they had a privileged life, had political influence, were even credited with some magical powers (such as rooting runaway slaves to the spot), and retired with good pensions and marriages. This ancient institution ended after a Christian emperor, Gratian, confiscated its funding in 382 AD.

And Swan Vesta matches. They were short pocket matches but not safety matches: they were “the smoker’s match”, or the “strike-anywhere match”: to ignite them you didn’t need a raspy surface like the side of a usual matchbox, you could use the side of your sleeve. But this required chemicals which in 2018 were banned by the EU.