Adrian Dening's Stars Over Somerset

Wednesday, 29 November 2023 17:00

Monday 4th to Sunday 10th December 2023

I've spoken several times recently about "transits" where one of Jupiter's moons passes in front of the planet, casting a shadow. On the evening of Thursday 7th there is an opportunity to see the opposite effect - an "occultation" where a moon passes behind the planet and is obscured from our view.

Approaching 9pm, Jupiter will be located towards the south, with the constellation of Orion to the left of it and Saturn low on the horizon to the right.

At 9pm, the Galilean moon Io will be just starting to disappear behind the gas giant.

It will reappear again from behind the other side of Jupiter just after midnight.

If you would prefer an early morning, a little before daybreak, say around 6am on Saturday 9th, a 14%-lit Waning Crescent Moon will be visible towards the south east, with Venus just to the left of it, shining very brightly at a magnitude of -4.0 so an excellent chance to observe it.

Remember that the magnitude scale works back-to-front, so the more negative the figure, the brighter an object appears. With the naked eye from a dark location, you can see down to a magnitude of +6.0 and anything fainter than that needs binoculars or a telescope. The brightest star in the night sky, Sirius, has a magnitude of around -1.4 so it is very easy to see. To put that into perspective, our Sun (which doesn't really count because you don't see it in the NIGHT sky) would have a magnitude of -26. That's why you NEVER try looking at it through a telescope!