Stargazers’ chance to glimpse elusive Mercury

Stargazers are set to scour the skies above the Capital for a rare glimpse of the elusive planet Mercury.

The Royal Observatory on Blackford Hill. Picture: comp
The Royal Observatory on Blackford Hill. Picture: comp

One of the smallest and fastest moving planets in the solar system, Mercury’s close proximity to the sun often makes it difficult to spot in the night sky.

But until Sunday, the planet’s 88-day orbit will be at its furthest distance from the sun, making it easier to pick out among the other stars.

And this year Mercury will be occupying the same patch of sky as its much brighter neighbour Venus – a rare alignment that occurs every five years and sees the larger planet act as a handy celestial signpost to finding Mercury.

John Davies, an astronomer at the Royal Observatory, said those looking to spot the planets should ensure they have a clear view of the south-western horizon as the sun sets – leaving Mercury visible to the naked eye for around an hour as twilight kicks in.

He said: “Your only chance to see Mercury is when it’s at its furthest elongation from the sun, and the sun has just set. Before the sky is even properly dark Mercury itself will set.

“The reason it’s of interest at the moment is that Venus is very close to it in the sky, so you should see two planets in the same view. You can often see Venus in a properly dark sky, but Mercury you never can.

“To see it, I would go and find somewhere with a clear view of the south-western sky, and just wait for the sky to get dark. Venus will be very bright and low in the sky, and then just below and slightly to the right you should see a fainter star – and that’s Mercury.”

Mr Davies said that over the next few days Venus would be “brighter than the brightest star you will ever see” and would look almost like a searchlight in the night sky, allowing stargazers to easily pinpoint its location.

He added: “You will probably be able to see Venus and Mercury before you see any other stars. The next few days will be the best time to see it.

“The clue is that they won’t twinkle – stars tend to twinkle in the night but planets don’t.

“But you must have a clear view of the horizon to see it – even the Pentland Hills would be enough to block it out.”

Mercury sits at a distance of 48 million miles from Earth and 36m miles on average from the sun, which it revolves around in an elliptical orbit – meaning it should be visible in the night sky around three times every year.