Get ready to observe the
RED PLANET You may be missing bright Venus, but one of the best appearances of Mars is approaching. Pete Lawrence looks ahead to its favourable opposition in October
he night sky in the first half of 2020 was dominated by brilliant Venus in evening twilight. With Venus now in the morning sky, the low southern planets Jupiter and Saturn have taken up the reins in the evening sky. Later this year, however, there’s a big planetary event to look out for as the Red Planet appears high and bright in evening skies. Indeed, this autumn we’ll see the best opposition of Mars for many years to come.
A planet is said to be in opposition when the Earth lies directly between it and the Sun. As the planet sits in the opposite part of the sky to the Sun, it’s positioned closest to Earth for its current ‘apparition’, or period of visibility. It’s a good time to observe a planet, because it will appear bigger than usual. Opposition is a big deal for Mars because it’s a long way from Earth for most of the time, looking dim to the naked eye and small when viewed through a telescope. But as the distance between our worlds shrinks, Mars brightens considerably, while expanding in size through the eyepiece of a scope to be large enough for surface detail to be seen easily.
Mars oppositions occur every two years and two months (or to be precise, every 779.94 days) and this year opposition falls on 13 October. In the run up to this date Mars will show a gradual but dramatic brightening, surpassing Jupiter’s brilliance on 24 September to become the second brightest planet after Venus. And it will remain bright for weeks afterwards, well into November. Indeed, mid-November may be the time to observe Mars if
Tyou have a young family or a fledgling interest: even though Mars won’t be as bright then, it will reach its highest position in the sky in the early evenings, which is a convenient time for many observers. To the naked eye the salmon pink colour is incredible when it becomes bright; it’s an unmistakable sign that you are looking at the Red Planet.
Bright pairings
Just like Venus earlier this year, there will be some great conjunctions between Mars and the Moon to feast your eyes on. Just after 01:00 BST on 12 July (midnight UT on 11 July), mag. –0.7 Mars sits 3˚ westnorthwest of a waning gibbous Moon. On 9 August at 04:30 BST (03:30 UT), mag. –1.3 Mars is located 3˚ northeast of the waning gibbous Moon. This is an interesting conjunction because it should be possible to stay with both objects after sunrise: just prior to setting at 11:00 BST (10:00 UT), they appear 1.1˚ apart.
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This month, on the night of the 11th/12th, Mars and a waning gibbous Moon rise together
Planetocentric longitude 180º