Excitement in the Moon Clock World! There will be a total Lunar Eclipse on Friday 27 July 2018, visible from most of the UK, including London.
Friday is the day of the Full Moon: lunar eclipses occur when the moon and sun are on the opposite sides of the earth, which is also the condition for Full Moon. However, the earth’s shadow must fall completely over the moon for a total eclipse. Because the moon’s orbit is slightly tilted relative to the earth’s orbit round the sun, it is only occasionally that the moon crosses the directly into the earth’s shadow at full moon. Usually, it is slightly above or below the shadow. The eclipse will actually start before the moon has risen in London. The eclipse will be total at 20:49 (moonrise) reaching a maximum at 21:21 and totality will end at 22:13. During this period it will be very close to the horizon, so will only be visible from locations with a clear view to the South East.
The next total lunar eclipse visible in London is on 21 January 2019. This will occur during the small hours, starting at 2:36 am. There will be a partial lunar eclipse in July 2019.
Lunar eclipses never occur alone: there is always a solar eclipse at the new moon preceding or following the lunar eclipse, when the moon comes directly between the sun and the earth. Sometimes, there can be solar eclipses at both these new moons, and that is what is happening this summer! Of course, solar eclipses may not be total, and may not be visible across the whole globe. Indeed, due to the relatively small amount of obscuration caused by the moon, total solar eclipses are much rarer than lunar eclipses: they do not last as long and are visible from a much smaller area – sometimes visible only over areas of ocean.
Apparently, there was a partial solar eclipse on 13th July 2018 and there will be a partial solar eclipse on 11 August, but it will not be visible in London. The next fairly full solar eclipse in London is not until the evening of 12th August 2026.
I gather that the ephem library is capable of calculating eclipses, but I shall not be adding this to the clock! However, if I get a photo of the Lunar Eclipse, I will put it on here.
After more than a month of very hot, dry weather, guess what? At 6 pm on the evening of the eclipse, there was a deluge! No thunder, no lightning, just torrential rain for half and hour. The sky had been clouding over since mid-afternoon, and I hoped that after this storm, it would clear. It didn’t. In hope, rather than in expectation, I headed for the North Downs above Reigate. From here there was a clear view to the south, with the south downs, running along the channel coast, in the very far distance. But in the far south, the sky was heavy. And I could see flashes of lightning in those clouds. An occasional spectacular fork that spanned tens of miles. The distant storm moved off eastwards, so at least I stayed dry, but there was no chance of seeing the moon. So I had to find this photo.
That’s been my luck with eclipses. I went to Cornwall for the August 1999 total solar eclipse, but I encountered the thickest cloud cover imaginable and it didn’t even get particularly dark at totality. Is there something about the position of the sun and moon that causes the jet stream to deviate and drag wet weather in from the Atlantic?
The next lunar total eclipse is in January … not a good time for a clear sky, but we can live in hope!