On the afternoon of Sunday, 13 March, ochre-coloured planet Mars crosses the constellation border of Libra into Scorpius. Now just ten weeks from opposition, the Red Planet is growing in both apparent size and brightness as the distance between our two worlds decreases.
The angular diameter of Mars reaches 10 arcseconds in mid-March, meaning that a telescope magnification approaching 200x is required to enlarge its 90 percent illuminated disc to the same size as our Moon appears to the unaided eye.
On the morning of Wednesday, 16 March around the onset of nautical twilight (~5am GMT for the centre of the British Isles), planets Mars and Saturn straddle the southern meridian where they are highest in the sky and best placed for observation. They form almost an isosceles triangle with first-magnitude star Antares below.
On the 16th, magnitude -0.1 Mars passes just 9 arcminutes from beautiful multiple star beta (β) Scorpii, otherwise known as Graffias, which means ‘claws’ in Arabic. On 16 March you can observe Mars and the 14-arcsecond-wide double star in the same telescope field of view at magnifications up to about 200x.
The two main component stars of Graffias — magnitude +2.6 β1 and magnitude +4.9 β2 — are easy to resolve in even the smallest telescope at magnifications of 50x or more. They orbit each other once in about 16,000 years and lie some 530 light-years from Earth. The beta Scorpii system actually consists of six stars in total.
Inside the magazine
Find out everything you need to know about observing Mars, Saturn and the other planets currently in the night sky in the March 2016 edition of Astronomy Now.
Never miss an issue by subscribing to the UK’s biggest astronomy magazine. Also available for iPad/iPhone and Android devices.