Twenty years ago today, as you'll no doubt remember, a totalsolareclipse could be seen from the UK.
Total solar eclipses don't come around very often so I booked a week long holiday in Cornwall at great expense and awaited the glorious spectacle. It was sunny at ten past eleven on every other day that week, but on Wednesday morning the clouds rolled in and I saw pretty much nothing. Friends in London told me they'd seen the whole thing perfectly, but all they really saw was the sun 97% obscured and the magic only kicks in at a hundred.
I'll not repeat my 1999 eclipse story because I've blogged it before. Instead I thought I'd look forward to the UK's next total solar eclipse, and more specifically London's next total solar eclipse, because they could be spectacular. Just don't get your hopes too high, because you'll likely be dead long before either of them happens.
Total solar eclipses are rare beasts because the moon's orbit doesn't usually pass precisely between the Earth and the sun. And even when everything does align the shadow cast is fairly narrow, so the path of totality can never be more than 167 miles wide. On average a single point on the earth's surface only sees one total solar eclipse every 375 years, which is why you haven't seen one from your back garden recently.
We can expand the chance of experiencing a total solar eclipse by considering an entire country, in this case the United Kingdom, so let's do that. The UK last saw a total solar eclipse on August 11th 1999, and before that 30th June 1954, and before that 29th June 1927. Sounds promising. But here's a clickable list of all the years a total solar eclipse has been visible from the UK over the last four centuries, and that's not very promising at all.
So, just seven, and with a 203-year gap skipping the whole of the 19th century.
And it's worse than that, because not all of these total eclipses were readily visible. The total solar eclipse of 1954, for example, only clipped the northernmost of the Shetland Islands so crossed the homes of only two thousand people. The total eclipse of 1927 only lasted for fifty seconds as it sped from Middlesbrough to Snowdonia, whereas the total eclipse of 1715 managed over four minutes. I should also point out that I'm using the current definition of the United Kingdom, which didn't yet exist in 1654 when a total eclipse swept across the north of Scotland.
Now let's look forward. Here's a clickable list of all the years a total solar eclipse will be visible from the UK over the next four centuries.
The 21st century is a real disappointment with just one total solar eclipse lined up, on 23rd September 2090, and that's 71 years distant. Again Cornwall and Devon are the favoured locations, but this time with the south coast cast into shadow as far as Hastings. The timing's not great though, occurring just before sunset on a September evening, so quite low down in the western sky. I should add that another total eclipse will have hit the Channel Islands a few years earlier, on 3rd September 2081, but they're not officially part of the UK and you'll likely be dead for that one too.
By contrast, the 22nd century truly delivers. An astonishing six total solar eclipses will be visible in the UK between 2133 and 2200, which is the same number as occurred during the previous 400 years. A seventh will cross Jersey in 2142, but again we can't count that. Two of the six are distinctly peripheral - 2133 scrapes the Outer Hebrides and half of Shetland, and 2160 is essentially the Scillies and Lands End only. But others hit the mainland more convincingly, with most of the UK seeing at least one total eclipse, and residents of York, Morecambe, Glasgow and Downpatrick seeing two. South Uist in the Outer Hebrides appears to be in the sweet spot with three total solar eclipses within 18 years.
Another galling feature, from a current perspective, is that in 2133 and 2135 total eclipses will occur just two years apart. But the 23rd century can offer a pair even closer than that, with one in January 2289 and another in June 2290 - both of them visible from St Kilda. The most common gap, however, is about 90 years, including 1999-2090, 2200-2289 and 2290-2381.
Which brings me to total eclipses visible from London. And they're disappointingly rare.
The total eclipse of 3rd May 1715 followed the discovery of Newtonian mechanics so was the one of the first to be accurately predicted in advance. Edmund Halley made his name by calculating path and timings, and by conveying this information to the wider populace via a simple map. The eclipse was visible across most of England and Wales, with its line of totality stretching from the Wash to the Lizard. The entirety of what's now Greater London fitted comfortably within the shadow's path (as did the whole of the West Midlands, East Anglia and the South West). Even the weather played ball.
And then a 436 year gap.
Greater London's next total eclipse will take place on 14th June 2151. It'll be a Monday, and the great spectacle will occur around half past seven in the evening, British Summer Time permitting. You won't be here to see it, but if you're reasonably young your grandchildren might.
But only part of Greater London will see it, a very small area to the northeast of the capital, and the other 93% misses out. Here's an approximate map I've knocked up (and here's a more accurate map from NASA).
The edge of the path of totality enters London in Crews Hill and heads southeast via Chingford, Fairlop, Chadwell Heath and Elm Park. Enfield Lock is in the zone, but Enfield Town misses out. One end of the platform at Roding Valley station gets lucky, the other end does not. Romford and Upminster are comfortably inside, but Barking and Dagenham are out. London's maximum eclipse will be near junction 28 of the M25, where totality almost scrapes one minute. But you'd be a fool to watch the eclipse from London when you could enjoy a minute and a half in Southend, two minutes in Colchester or over two and a half in King's Lynn, Leeds and Lancaster. Here's a map showing the full extent of totality across the UK (with the longest duration down the centre of the red stripe).
Glasgow gets it, Edinburgh doesn't. Durham's in but Newcastle's out. Llandudno yes, Anglesey no. Dover's a hit but Folkestone's a miss. Cambridge is properly in the dark whereas Oxford's only 99½% obscured. Unusually this particular total eclipse will cross all four of the home nations (assuming they're still part of the UK at the time, assuming the UK still exists).
While we're here, let's list all of London's total solar eclipses for the remainder of the millennium. Both of them.
The total eclipse of 5th May 2600 should be visible from most of the western half of Greater London, which is encouraging, but takes place at about six in the morning so will be low in the eastern sky. The total eclipse of 21st July 2726 will be a noonday event, therefore easier to see, but will only be visible south of a line from Twickenham to Sidcup. Overlap all three of this millennium's total eclipses on the same map and it shows that most of London will see at least one, but a significant chunk near the Thames estuary will see nothing. Kingston and Hainault get two. The Royal Greenwich Observatory is alas in not quite the right place.
Of course by the time these eclipses occur London will probably be larger than it is now, or administratively unrecognisable, or partially flooded, or completely destroyed, so delving this far into the future is essentially pointless. But the machinations of the stars and planets remain reliably predictable, whatever mess we've made on the ground, so the moon's shadow will still blot out the sun whether or not anyone's around to see it.