Keep an eye on the western sky after sunset this week to watch a beautiful sequence unfold over several evenings. A young crescent moon moves first past Venus and then Jupiter, creating a chance to track the moon’s movement through its orbit around the Earth.
The chart shows the view on 18 May looking west from London at 22.00. The moon will be just 2.4 days old, and just 6.2% of its visible surface will be illuminated. Close to this slim arc of light, Venus will be shining brightly, unmistakable even in twilight.
Jupiter sits a little higher and dimmer, but is still prominent. Finally, dimmest of all are the stars of Gemini; the twins, Castor and Pollux. Over the next few nights, the moon moves eastward, towards Jupiter, growing in percentage illumination as the angle it makes to the sun changes night after night.
For the best chance of seeing the alignment, choose a viewpoint with an unobstructed western horizon.
From the southern hemisphere, the view will be a little easier to see. At this time of the year, the ecliptic, the path followed by the sun, moon and planets, is tilted upwards more steeply from the horizon. This will place the conjunction higher in the sky at sunset.
