Prepare this week to track down a perennial celestial beauty, a young crescent Moon. This week, it appears in the constellation of Taurus, the Bull. New moon takes place on 12 April at 03:30 BST, so watch the western sky at sunset for it to emerge from the twilight over the coming days. The chart shows the view looking west from London at 21:00 BST on 16 April. (Viewers in the southern hemisphere need to look on 17 April at twilight.) There will still be a faint glow from the sun on the horizon and the moon will have just 18% of its visible hemisphere illuminated. The moon will be at approximately the same altitude as the red giant star Betelgeuse, which marks the shoulder of Orion, the hunter, and it will be heading towards the red spot of Mars, higher in the sky. Over the next weeks and month, keep an eye on Mars: it will get fainter and appear ever closer to the horizon at nightfall. By autumn, Mars will have temporarily disappeared from view altogether. This is because the red planet’s orbit is carrying it away from Earth and around behind the sun.