Starwatch: the moon meets the lion's brightest star

Every month the moon slips past the bright star of Regulus in Leo, the lion. It is a good opportunity to identify the constellation, which doesn’t need too much imagination to turn it into a lion. This month the pairing takes place on 25 June. The chart shows the view looking west from London at 23:00 BST. Leo will be heading down towards the horizon. An hour or so later it will have set, and the moon along with it. The moon itself will be a pleasing waxing crescent with about a quarter of its earthward face illuminated. From the southern hemisphere, Leo will appear upside down in the north-western portion of the night sky.

Regulus is a blue-white star with a mass of around 4 times the sun and radius of 3 times the sun. At approximately 12,500 Kelvin, its surface temperature is about twice that of our star. Lying at a distance of around 80 light years, Regulus is a triple star, possessing two much fainter companions that are sadly impossible to see with the naked eye.