Look to the southern sky at dusk on 12 January to see the 6-day-old waxing crescent Moon just 6½ degrees below magnitude +0.6 Mars in the constellation of Pisces. If you own wide-angle 7× or 8× binoculars, you can see the pair in the same field of view. Note that the Moon’s apparent size has been enlarged for clarity in this illustration. AN graphic by Ade Ashford.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.
Many will be looking skyward to see terrestrial pyrotechnics this Bonfire Night, but if you own a small telescope and can escape the light pollution, you can see the waning gibbous Moon hide three naked-eye stars in Taurus on the night of 5—6 November, culminating in first-magnitude star Aldebaran in the small hours of Monday morning.
Saturn’s summer apparition for 2015 is drawing to a close as the ringed planet is highest in the southern sky before sunset for observers in the British Isles, but it can still be found in the bright evening twilight if you have a convenient guide — like tonight’s gibbous Moon.
