The moon will help us track down Saturn, the sixth planet in the solar system, this week. Currently residing in the constellation of Pisces, the fishes, Saturn is gradually building in brightness as the Earth’s orbit is carrying the two planets closer together. This year, the closest approach between them will occur on 21 September.
In the meantime, the moon can be useful as your guide to locate Saturn and then watch it over the coming months as the planet performs a lazy pirouette in the sky, known as retrograde motion. This is an optical illusion caused by our changing line of sight to the planet as Earth overtakes it on the inside.
The chart shows the view looking east from London on 16 July at midnight BST, soon after the moon and Saturn have risen.
The moon will be almost 20 days old and in its waning gibbous phase, rising later each night. Just over 72% of the moon’s visible surface will be illuminated on this night, and it will be 373,842km away from Earth. Saturn, on the other hand, will be 1,368m km away.
The conjunction will be easily visible from the southern hemisphere.
