Starwatch: Mercury and Venus return for a twilight show | Astronomy

There’s a challenging but beautiful sight awaiting keen-eyed stargazers this week. Mercury and Venus have returned to the evening sky and are nestled together in the sunset twilight.

The chart shows the view looking south-west from London at 16.30 GMT on 24 December. The planets are visible for about three-quarters of an hour after sunset, but a clear horizon is needed to see them.

Start your vigil at sunset, about 15.52 GMT, and keep a sharp eye open. Venus will be the brighter of the two, and so easier to see. The only other celestial objects visible in that patch of sky will be Altair and Saturn. A thin sliver of the waning crescent moon might just be visible as well, but there are no guarantees about seeing that ghostly presence.

It will be easier to see the planets from the southern hemisphere, as they will be slightly better placed. Again, look south-west in the 45 minutes after sunset. Mercury will be above and to the right of Venus; the crescent moon will be to the left at the same altitude of Venus. From now until July 2023, Venus will remain in the evening sky, rising higher and higher to become the brilliant “evening star”.