As nautical twilight starts at 7am GMT for the centre of the British Isles on 9 January, planets Venus and Saturn are separated by just 9¼ arcminutes — less than a third of the apparent diameter of the full Moon — very low to the southeast. They were at their closest (5 arcminutes) at 4am GMT, but below the UK horizon at that time. Both planets lie 6⅔ degrees to the upper left of star Antares, so all three will fit within the field of view of a 7×50 binocular. AN graphic by Ade Ashford.On Saturday, 9 January at 3:57am GMT, magnitude -4.0 Venus passes just 5 arcminutes — less than one tenth of a degree — north of magnitude +0.5 Saturn. While the instant of closest approach will be missed by observers in the extreme west of Europe as Venus and Saturn will still be below the horizon, by 7am GMT the ‘double-planet’ will be high enough to be glimpsed with the naked eye very low to the southeast from the UK.
By 7am GMT the gap between these two prominent planets will have widened to 9¼ arcminutes — still less than a third of the apparent diameter of the full Moon. Observers with motorised equatorial or GoTo mounts can track the rising pair in the same eyepiece field at magnifications up to 175x until Saturn fades into daylight.
As always, whenever observing in daylight please take extreme care lest the Sun enters the field of view of your telescope or finder with disastrous consequences for your eyesight or anyone else who accidentally looks at it.
Two days before its final plunge into Saturn, the Cassini spacecraft turned its camera toward the ringed world to take a series of images for a colour mosaic, capturing a last evocative close-up until a new mission reaches the planet.
Dazzling planet Venus continues to be a useful celestial signpost to other planets at dusk. Having already showcased Neptune and Mercury this year, the brightest planet has a close conjunction with Uranus on the UK evening of Sunday, 8 March. The pair lie just 2.2 degrees apart against the constellation backdrop of Aries, simultaneously visible in typical 10×50 binoculars.
Saturn’s beautiful rings form a striking feature, cutting across this image of two of the planet’s most intriguing moons: Titan (diameter, 3,200 miles) and Enceladus (313 miles). The rings have been a source of mystery since their discovery in 1610 by Galileo Galilei, but there is not full agreement on how they formed.
