It's a natural phenomenon not to be missed - so how, where and when can you see it?
A total solar eclipse happens when the moon comes between the Sun and the Earth and casts the darkest part of its shadow (the umbra) on Earth. The darkest point of the eclipse is almost as dark as night.
Londoners will be treated to a partial solar eclipse, rather than the full thing, but it will still be pretty impressive - and pretty eerie - when the moon covers the vast majority of the sun.
If you're into coordinates, they are given as 119°East-southeast 20.6° for the start of the eclipse; 134°Southeast 28.9° for the peak moment and 154°South-southeast 35.3° for the finale.
If you are a solar eclipse hunter, there are only two places in the world that are easy-to-access locations – Svalbard, an island belonging to Norway and the Faroe Islands. Get packing now.
If you're in London, you'll want to start looking out for it is around 8:25am, which is when the moon will touch the Sun's edge. The maximum eclipse will be at 9:31am, when the moon is closest to the centre of the Sun. The eclipse will end at 10:41am.
If you're not based in the capital, this handy map shows the best times to see it in the rest of the country:
It goes without saying that looking at the sun without anything to protect your eyes is a bad idea. Experts have warned against even looking at the eclipse with sunglasses on, and there is a strictly no-photos (or selfies) allowed rule.
The best way to see the eclipse, according to the College of Optometrists, is to use a pin-hole camera. Time to dust off your GCSE science books if you don't remember how that works.
And there's more
According to the Met Office, this evening there will also be a supermoon, which means the Earth and Moon are as close together as they can be.
"This makes this 2015 Spring Equinox eclipse a supermoon eclipse, meaning a supermoon, equinox and eclipse will all fall on the same day," it said.
What if we miss it?
If you're slaving over a hot desk or the killer smog ruins total eclipse day for everyone, don't get too gloomy. There are four eclipses in 2015 (though, to be fair, this is the best and most dramatic).
There will be another partial solar eclipse on September 13, and two lunar eclipses - on April 4 and September 28.