Mars at its closest

The planet Mars is at its closest to us since 2003, and the planet is unmissable quite low down in the south at about midnight. Its orange colour is very noticeable, and it’s extremely bright.

Mars, photographed on 1 August 2018, when the planet was close to its largest-possible diameter. Even with an 80 mm refractor markings are visible, though with reduced contrast. Photo: Robin Scagell

You might think that this would be the best time for years to observe the planet. And it is – but only if you live in the southern hemisphere. From the UK Mars only rises about 12ΒΊ above the horizon, so our view is subject to a lot of turbulence from the atmosphere. If the jet stream stays away from us, which it has done throughout the recent hot spell, the viewing – or what astronomers call seeing – isn’t too bad, but it’s still pretty poor compared with when the planet is higher in the sky. And the atmosphere acts as a prism, giving a red fringe to the planet’s lower edge and a blue fringe to the upper.

So the expert observers are looking forward to the 2020 approach (known to astronomers as an opposition), when Mars isn’t quite as close (see the graph below) but will be higher in the sky. Or they are going down to more southerly latitudes where the planet will be much higher in the sky, or even overhead, giving superlative viewing conditions.

But don’t let put you off taking a look. Even through a small telescope Mars shows a noticeable disc, and this is the best chance to see it looking really big for a number of years. However, even if the atmosphere is steady, you might wonder where are those dark markings that look so prominent on the Hubble and spacecraft photos? Actually, Mars has recently experienced a major dust storm, and for a while many of the dark markings were obscured altogether. The whole planet even looked more yellowish than usual. The dust is beginning to clear, but many of the markings are less obvious than usual. British observer David Arditti, imaging using a 14″ has suggested that the markings have only 25% of their usual contrast.

By the way, you may have read on the internet that Mars will appear as big as the Moon. This is a nonsense story that occasionally resurfaces, and you can find out about it at our Mars hoax-busting page.

The low southerly declination and the dust storm has made this a difficult time for Mars observers. Experience shows that we get better views when the planet is higher in the sky than when it is particularly close but low down. Later in the year Mars will get a little higher in our skies, though it will be farther away, so as the dust storm subsides we might even get better views in a month or two. So don’t give up yet!

Mars oppositions
Graph showing how Mars is much closer and larger at some oppositions than others. The opposition of 2003 was the closest for nearly 60,000 years, but that of 2018 is almost as close.