Observers in the British Isles and Western Europe looking up at the waxing lunar crescent around nautical dusk (some 1½ hours after sunset in the UK) on Saturday, 12 January will notice that the Moon is not alone – an orange-coloured magnitude +0.6 ‘star’ lies less than a span of a fist at arm’s length above it. This bright interloper in the otherwise modest stars of the constellation of Pisces is none other than Mars.
Some 24 weeks after its close opposition of 2018, the Red Planet presently lies almost 204 million kilometres from Earth, hence its tiny gibbous disc spans just 6.9 arcseconds. Not surprisingly, little in the way of martian surface detail will be evident except in large backyard instruments.
Our Moon has half the physical diameter of Mars, but the Red Planet appears so much smaller since it lies more than 500 times farther away this night. In fact, you need a telescope magnifying in excess of 260× to enlarge Mars to the same apparent size as the adjacent Moon appears to the unaided eye on 12 January.