PICK OF THE MONTH
Best time to see: 28 July, 00:20 BST, (July 27, 23:20 UT) Altitude: 11º Location: Capricornus Direction: South Features: Light and dark surface regions, polar caps and weather Equipment: 3-inch telescope or larger
Mars reaches opposition on 27 July at which time the planet will be looking its largest and brightest. This particular opposition occurs when the planet is low in the sky from the UK. Mars will get to an apparent diameter of 24 arcseconds from 23 July through to 9 August, but reaches a maximum altitude of 11° as seen from the centre of the UK. Although this will add an extra challenge, take heart from the fact that for the next opposition on 13 October 2020, Mars will reach an altitude of 42° and will be only marginally smaller and less bright.
At the start of July 2018, Mars will appear to be travelling east against the stars, but by the end of the month its direction will have changed so that it appears to be moving west. Through a telescope it’s the southern polar cap of Mars that’s currently tilted towards us, by around 12°. The dark, V-shaped feature known as Syrtis Major is centrally placed at 01:00 BST (00:00 UT) on 2 July.
Mars rotates once on its axis every 24 hours and 40 minutes, which can lead to a degree of frustration when observing the planet. To explain this, imagine a feature centrally positioned on the planet’s disc. At the same time the next day, the feature would appear in the central position 40 minutes later. The day after that it would reach the central position 80 minutes later than on the first night, and so on. Observing the planet at the same time on consecutive days essentially gives you a re-run of what you’ve been looking at on previous days! To the naked eye, Mars appears to brighten impressively throughout July, starting off at mag. –2.2, but increasing in brilliance to mag. –2.8 around opposition. This makes it brighter than Jupiter and the second brightest main planet after Venus.
Mars in opposition will shine brightly in July but annoyingly it’s also very low on the horizon
The V-shaped Syrtis Major is one of the most easily recognised features on Mars