Adrian Dening's Stars Over Somerset

Wednesday, 13 September 2023 17:00

Monday 18th to Sunday 24th September 2023

If you are up early, any morning next week and look towards the east, Venus will have risen above the horizon from about 4am. It is currently shining very brightly at a magnitude of -4.5

By around 5.30am, Venus will have climbed higher in the sky and to the left of it, Mercury will be popping its head up above the horizon. Towards the end of the coming week, Mercury reaches its greatest western elongation from the Sun (when it appears to be furthest from it). Mercury won't be quite as bright as Venus as it currently has a magnitude of -0.3

Remember that the magnitude scale is back to front, so the more negative the number, then the brighter an object is. To put that into context, our own Sun has a magnitude of around -26 so that is why you never attempt to look at it through binoculars or a telescope! For this reason, I would not be tempted to use your telescope to get a better view of Venus and Mercury next week as the Sun will be rising in the same spot a little later and you don't want to accidentally catch a glimpse of it!

While we are on the subject, on the morning of Saturday 23rd, the centre of the Sun crosses the celestial equator as it moves from the northern celestial hemisphere to the southern celestial hemisphere. What on Earth does that mean? Well it marks the autumn equinox or the point on the autumn calendar when we have equal periods of night and day. In other words, we are halfway towards the shortest day in December - hard to believe after all that hot weather last week!

Screenshots courtesy of Stellarium
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