Adrian Dening's Stars Over Somerset

Wednesday, 8 January 2025 18:40

Monday 13th to Sunday 19th January 2025

If you look towards the south east at 7pm on Monday 13th, Jupiter will be an easy "naked eye" target, shining at an extremely bright magnitude of -2.6 and sitting above the constellation of Orion.

Whip your telescope out and there is an opportunity to see the shadow of Jupiter's moon Ganymede as it transits across the face of the planet. The shadow should be visible until 9pm. With even a modest telescope or binoculars, you should be able to observe all four of Jupiter's Galilean moons - Io, Europa, Ganymede and Callisto.

Sometimes you can't see all four moons at once because as they orbit around the planet, the moons are blocked from our view, but at 7pm on 13th they will all be visible. At that point, you will actually be witnessing what Galileo saw in the 1700s, when he first realised that we orbit around the Sun along with the other planets in the Solar System.

When the transit of Ganymede's shadow has finished, look to the left of Jupiter and a Full Moon will be very close to planet Mars. Mars will be easy to spot at a magnitude of -1.4 and it has an obvious red tint.

Of course, around the time of a Full Moon, its light pollution spoils the contrast of faint deep sky objects, so let's stick with our neighbours in the Solar System.

Look towards the south west around 7pm on Saturday 18th to see a magnitude -4.6 Venus close to a dimmer magnitude +1.1 Saturn as the pair set below the horizon.