Saturday, December 2, 2023

Moon’s special effect


moon halo
Moon halo

BrianAmateur astronomer Brian Watkiss peers into the Village night sky.

December, the month of dark, dark days – no, I don’t mean the 12th. The Sun sets at around four in the afternoon and doesn’t peep back over the horizon till eight in the morning and it never rises very high in the sky, even at noon.

Winter Solstice occurs in the early hours of the 22nd and then, very slowly, the hours of daylight start to increase. This is why our ancestors decided to have a big celebration at around this time every year, and good for them!

This means, of course, that we can start sky-watching as soon as everyone is home from school. So, don’t take your coat off but get out and find a really good view of the southwest horizon and look at the glow of the sunset.

Jupiter is there briefly, almost impossible to spot but you should see that brightest of planets, Venus. You will have to be quick though because apart from being very close to the horizon, it’ll be gone by about quarter past five.

Saturn should start to become visible then, just a little higher, but it too has vanished by six-thirty. As the days go by, Saturn gets lower and lower and is gone before the end of the month.

That quirky little planet Venus, though, has other ideas. It actually gets higher in the sky and passes by Saturn on the 11th. By the end of the month it will be the bright evening star that we know and love, and on the 28th will look spectacular next to a very slim crescent Moon.

The Moon is full on the 12th and, for a few days either side, keep an eye out for a rather special effect. This time of year often produces those hazy clear nights when you can see the stars but they look sort of misty.

This is due to very fine ice crystals high in the atmosphere and they can do something unusual to the Moon. They can refract the Moon’s light and create a halo around it – and if conditions are right, a slight rainbow effect can be seen.

It can happen any time of year but I find it more common during these late autumn/early winter nights. It can happen to the Sun too, but less often.

Unfortunately, that bright full Moon will tend to drown out the meteors of the Geminid shower which peak on the 14th, but the Ursids on the 23rd are more favourably timed. Just keep an eye on the darkest part of the sky for a few moments whenever you’re out after dark.

In the world of space travel, the 4th should see a launch of a SpaceX Dragon cargo vessel to the ISS and just possibly, the 17th might, at last, see the launch of Boeing’s Crew carrying Starliner craft, albeit without a crew. Only time and will tell.

I wonder if heavens-above will track that famous reindeer-hauled craft on the 24th? Happy Christmas.