Sunday 6 November marks exactly 24 weeks since planet Mars was at opposition in the summer sky. It is also the date when you can see the Red Planet close to the six-day-old waxing crescent Moon low in the southern sky an hour after sunset in the British Isles and Western Europe.
Back in the last week of May, Mars shone at magnitude -2 and it was at its closest to Earth for over a decade. Having moved east along the ecliptic passing from Scorpius, through Ophiuchus into Sagittarius in the intervening weeks, the Red Planet is still hanging on in the evening sky — though now it is merely a shadow of its summer glory.
Mars is currently 2½ times farther from Earth than at the end of May, hence its disc seen in a telescope now measures just 7.3 arcseconds in diameter. (This means a magnification of 250x is required to enlarge the Red Planet to the size of the Moon as seen with the unaided eye.) The combination of increased distance and decreasing phase means that the planet is almost ten times fainter than its summer best too. However, should you have good seeing at lower latitudes, Mars presents the prominent v-shaped Syrtis Major surface feature to Western Europe at dusk on 6 November.
By the time that the Moon has cycled through another lunation and caught up with Mars again on 5 December, the Red Planet will have moved through another zodiacal constellation to be found in eastern Capricornus in the southern sky at dusk.
Inside the magazine
For a comprehensive guide to observing all that is happening in the current month’s sky, tailored to Western Europe, North America and Australasia, obtain a copy of the November 2016 edition of Astronomy Now.
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