Starwatch: crescent moon to join Venus in evening twilight

After sunset on 20 March, look up to catch the earthshine, when the unlit face of the moon will be faintly visible Look west after sunset on 20 March and you will find a beautifully slender crescent moon in conjunction with the glorious beacon of Venus, low in the evening twilight. Venus has been prominent in the dusky skies for several weeks now, outshining every star. On 20 March it will be joined by a young moon, just under 2 days new, and with only 3.7% of its visible surface illuminated by direct sunlight. The chart shows the view from London at 20.00 GMT on 20 March. Start your observations at sunset, about 18.30 GMT. Choose a location with a clear western view. Venus and the moon’s delicate curve will be seen first but do not stop there. Savour the view and watch for the unlit face of the moon to become faintly visible. This is the earthshine, produced by sunlight reflected from Earth onto the lunar surface and back at us. As twilight darkens, the contrast will improve, making the earthshine more visible still. Venus will be lower, but an unmistakably bright point of white light against the deepening blue. Observers in the southern hemisphere will have a harder job seeing th