Catch a glimpse of Mercury

Catch a glimpse of Mercury

The planet Mercury is definitely mercurial. It’s as hard to catch as quicksilver. But the closest planet to the Sun is in the evening sky right now, in the south-west just after sunset, so early January 2022 is a good time to look for it. Mercury is at its farthest from the Sun on 7 January, but it’s still around for a few days after that date.

You’ll need a good clear sky and a low horizon to see it, and because the sky is still bright at that time you’ll have to search carefully. Just as you are about to give up you will probably spot it as a starlike point, and once you’ve seen it it becomes easier to find it again. Saturn is also appearing in the evening sky in the same direction, although quite a lot fainter, so you may spot that as well. Binoculars would definitely help you to find both planets.

Where to look

Look to the south-west about 40 minutes after sunset or a bit later, in the brightest part of the twilight sky where the Sun has set. It’s much closer to the horizon and to the right of Jupiter, which is the bright planet in the south-west at the moment. The time of sunset depends on where you live in the UK, varying from about 16:10 in the London area to 15:40 in northern Scotland. But don’t leave it too long – there’s only a window of opportunity about 20 minutes long in which to view it.

The view about 45 minutes after sunset on 9 January 2022 as shown by the free astronomy software Stellarium, which you can also download for your phone.

Mercury is moving closer to the Sun as seen in the sky evening by evening, and will become too low to be seen easily by about 16 January. The next opportunity to view it in the evening sky will be at the end of April.

Viewing tip

If you have a phone app that shows the stars, and knows which way it’s pointing, this is the time to use it! It will show you exactly which direction to look in, and how high Mercury is above the horizon. But even then, it won’t be all that easy.

Catch fleeting Mercury in the morning

Catch fleeting Mercury in the morning

If you’ve never seen Mercury, then the next few mornings offer a great opportunity – but you’ll need to be quick!

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Mercury photographed in the morning sky on 28 October from Walmer, Kent, by Paul Sutherland

The closest planet to the Sun can never be seen in a truly dark sky because it cannot venture far enough away from it in the sky.

We only see it with the naked eye on one of its fleeting appearances in the evening or morning twilight, soon after sunset or just before dawn.

Currently, Mercury is in the morning sky and gets high enough above the horizon to be observable before the sky becomes too bright. The ecliptic – the path along which the planets appear to travel – is tilted steeply to the horizon on autumn mornings, from northern latitudes, so Mercury gets between 5° and 10° above the horizon before being lost in the dawn glow.

You need to look roughly eastwards to see Mercury, in Virgo. You will also need a clear horizon free of low cloud, buildings and hills. A sea horizon is ideal.

Mercury reached Greatest Elongation West on 25 October, when it lay 18° from the Sun, and shone at around -0.6, which is brighter than most stars.

Since then it has been slipping slowly back towards the Sun but you will have several more days into the first week of November to catch the planet it weather conditions are favourable.

Between 6.30 and 7am BST is an optimal time to seek out Mercury before the clocks go back on 31 October. After that, look an hour or so earlier local time, of course.

A fine waning crescent Moon will lie near Mercury on the morning of 6 November.

Binoculars will help you locate Mercury due to the brightening twilight sky and its low altitude. Make sure you don’t scan the sky with them after sunrise when it will be to late to see Mercury anyway.

Mercury will reach Superior Conjunction, on the far side of the Sun, on 29 November, after which it moves back into the evening sky.