On the UK night of 6—7 July 2017, three weeks after the opposition of Saturn in the constellation of Ophiuchus, the ringed planet can be identified as the magnitude-zero ‘star’ highest in the southern UK sky around 11:40pm BST. As seen from the heart of the British Isles at this time, Saturn struggles to attain a peak altitude of just 14 degrees, or three-quarters of the span of an outstretched hand held at arm’s length above the horizon.
While there is a slim chance that you can confuse Saturn with first-magnitude Antares in the constellation of Scorpius that lies 14 degrees (or one-and-a-half spans of a fist held at arm’s length) to the right of the planet, the supergiant star is the fainter of the two and has a reddish-orange hue in binoculars and small telescopes.Returning to Saturn in a small telescope, the UK night of 6—7 July is ideal for spotting the ringed planet’s largest moon, Titan. This cloud-covered world some 3,200 miles in diameter looks just like a magnitude +9 star close to its greatest westerly elongation from Saturn, some 4½ ring diameters away. Titan orbits its parent planet every 16 days, so expect to see it a similar distance to the east of Saturn on 14 July.
On the evening of Monday, 30 May, Mars is closer to Earth than at any time since 30 October 2005. This begs the question: just how close can Mars get? Ade Ashford gives you an overview of close Martian oppositions past, present and future. Also, Friday, 3 June sees the opposition of Saturn, the other planet visible low in the south around midnight.
Mercury is currently putting on a fine show in the east before dawn. Find a UK location with an unobstructed view due east an hour before sunrise to see the innermost planet some 6 degrees above the horizon from about 25 September—5 October. The very old crescent Moon lies just 2 degrees from Mercury at dawn on Thursday, 29 September.
In the pre-dawn twilight of Tuesday, 1 March, the 21-day-old waning gibbous Moon acts as a convenient celestial guide to planets Saturn and Mars. For observers in the centre of the British Isles, the best time to see this triple conjunction is shortly before 6am GMT, when the trio are highest in the sky to the south.