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A once-in-a-generation phenomenon will be played out in the sky over Ireland tomorrow

Mercury is set to pass across the sun tomorrow afternoon. You won’t see the phenomenon again this clearly until 2049.
May 8th 2016, 7:30 PM 72,153 44

1 Source: Astronomy Ireland

TOMORROW IS MONDAY. And lord knows Mondays aren’t much fun. But this one might be.

There’s going to be an astronomical phenomenon at play in the sky tomorrow afternoon. One you won’t get to see as clearly for another 33 years.

The transit of Mercury across the sun will be happening for eight hours tomorrow between 12.12pm and 7.42pm. It’ll be worth paying attention to. But what on earth is a transit you may ask?

“Well it’s very simple really,” explains David Moore of Astronomy Ireland, who will be throwing something of a transit-bash at their headquarters in Blanchardstown, north Dublin, for the event.

“Mercury will pass between the earth and the sun. It’s purely a lining up effect. But this is one of the rare occasions that the two planets will align perfectly.”

So, what you will see (if you choose to observe professionally – staring at the sun could blind you so a telescope with a solar filter is a necessity) is an (admittedly tiny) perfectly round disc moving across the outline of the sun over the course of eight hours.

Source: ScienceAtNASA/YouTube

It sounds very cool. And Moore is understandably excited.

“This is a real rarity. The last time you could view one in Ireland was in 2003. And you won’t see another one this clearly until 2049. So for a lot of us it’s a once-in-a-lifetime event,” he says.

And the weather is forecast to be excellent, and importantly not cloudy. It’s the best one I’m going to see anyway.

All eyes on the sky tomorrow so.

Here’s some of the science behind the transit. Mercury is orbiting the sun at a far greater pace than our own planet. It manages a full orbit once every 90 days in fact.

Unfortunately the orbits of the two planets are misaligned, meaning that while Mercury passes between us and the sun relatively frequently (given the fact it’s three times closer to the sun than we are), a transit which is perfectly visible to us is a rare event indeed.

And as you might imagine, even when the opportunity may arise (as it last did in 2003), the Irish weather can scupper things – on that occasion cloud covered our skies for the duration.

So make the most of this one is our advice.

nasa Source: NASA/Facebook

As mentioned before Astronomy Ireland will be running their own event on the day, which is free for anyone to attend, at their base off the Cappagh Road in Blanchardstown. The group are encouraging all and sundry to attend. “This is an event for all Leinster at the very least,” says David.

The transit will be watched by special telescopes around the world and live views of these will also be projected on to large screens at the facility.

And if you’re based in Dublin city centre there are a number of events being held especially to cater for you.

astro Source: Irish Astronomical Society/Facebook

The Irish Astronomical Society will be hosting a viewing using appropriate telescopes in St Stephen’s Green between 11am and 4pm, while nearby Trinity College will be holding a viewing event in the university’s Front Square from 12pm until 6pm. Perfect for popping into on your lunch.

Happy transiting everyone.

Read: Keep an eye on the sky tonight for a spectacular astronomical display

Read: Bad news for ‘Boaty McBoatface’ fans, good news for people who like David Attenborough

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Cianan Brennan


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