Have you ever seen a total solar eclipse? If you’ve never been tempted to make the journey (and you’ll need to travel since the next one in the UK is not until 2090!), know that it’s far more than seeing darkness in the day for a few minutes.
What is a total solar eclipse?
A total solar eclipse occurs when a New Moon gets precisely between Earth and the Sun, blocking the Sun’s light for a few minutes and throwing a moon-shadow onto the planet.
It gets murky, it gets cold, and shadows dance on the floor right before a ‘diamond ring’ of light around the moon sparkles for a second.
Instantly day turns to night and before your eyes the Sun’s hot white corona – its hotter inner atmosphere that’s normally lost in the glare of the Sun’s disk – reveals itself for a few mind-bending minutes.
That will happen for 2 minutes and 9 seconds in a narrow path of totality across South America on 14 December, 2020, but it’s not the only eclipse in the coming year.
What is a penumbral lunar eclipse?
There will be four penumbral lunar eclipses in 2020. Not to be mistaken for total lunar eclipses (also known colloquially as ‘blood moons’), they occur when the Earth is almost, but not quite between the Sun and a full Moon.
Thus Earth’s diffuse outer shadow – its penumbra – covers the Moon’s surface, thus blocking most of the light from the Sun from reaching the Moon.
The Moon doesn’t turn reddish, as during a total lunar eclipse, but a penumbral lunar eclipse is still worth noting.
If nothing else it’s an excellent opportunity to view and photograph a full moon high in the night sky without the normal glare.
10 January, 2020: Penumbral Lunar Eclipse
Solar and lunar eclipses always come as twins or triplets. That’s because when the Moon is in the right place to cause a solar eclipse at New Moon (crossing the ecliptic – the Sun’s apparent path through the daytime sky) it’s still in the right place at full Moon half-an-orbit later.
So two weeks after an annular solar eclipse on 26 December 2019 the moon will drift into Earth’s penumbra, losing it lustre for a few hours for anyone in Asia, Australia, Europe, and Africa.
From the UK the spectacle begins at 17:07 just after moonrise, peaks at 19:10 and ends at 21:12 on 10 January, 2020.
It will be by far the best view of a lunar eclipse for UK Moon-gazers in 2020.
5 June, 2020: Penumbral Lunar Eclipse
Occurring exactly two weeks before another annular solar eclipse, 2020’s second penumbral lunar eclipse won’t be much of a sight from the UK.
The maximum eclipse is before moonrise at 21:04, when only a portion of the full moon will be dulled, and it will be finished by 22:04 on 5 June, 2020. Asia, Africa and Australia get far better views of this one.
21 June, 2020: Annular Solar Eclipse
Towards the end of June there will be a ‘ring of light’ or ‘ring of fire’ eclipse, and in 2020, it’s a very special one.
Don’t read too much into the fact that it occurs on the date of the solstice (summer solstice in the northern hemisphere and winter solstice in the southern hemisphere) because that’s just a celestial coincidence.
An annular solar eclipse occurs when the Moon is further away from Earth on its slightly elliptical orbit, so not big enough in our sky to cover the whole of the sun; the Moon’s shadow cone doesn’t quite reach Earth.
This eclipse is rather special because 99% of the Sun will be covered, so it’s almost a total solar eclipse.
Consequently, it lasts a maximum of just 38 seconds, during which it may be possible to see some phenomena normally associated with a total solar eclipse, such as Baily’s Beads – beads of sunlight around the Moon streaming through the mountains and valleys of the Moon – either side of maximum eclipse.
They will likely be visible to those standing on the edge of the ‘path of annularity’, which stretches from Africa (the Congo, Democratic Republic of Congo, South Sudan, Ethiopia and Eritrea) through the Middle East (Yemen and Oman) and into Asia (Pakistan, India, Tibet, China and Taiwan).
There’s another annular solar eclipse in 2021, during which a 50% partial solar eclipse will be visible from the UK on 10 June 2021.
5 July, 2020: Penumbral Lunar Eclipse
Precisely two weeks after an annular solar eclipse there will be yet another penumbral lunar eclipse. This time it’s South America, North America and Africa that get the best views.
From the UK the spectacle is extremely brief, beginning at 04:07, with the Moon setting soon after at 04:45 on 5 July, 2020. Sadly it will barely be noticeable from the UK.
29-30 November, 2020: Penumbral Lunar Eclipse
A final penumbral lunar eclipse for 2020, this one precedes December’s total solar eclipse. Sadly it won’t be visible at all from the UK, with the Moon drifting into Earth’s penumbra just as the Moon sets. North and South America, Australia and East Asia will get the best views.
14 December, 2020: Total Solar Eclipse
This is the big one. 18 months after the last total solar eclipse in Chile and Argentina, totality again returns to those two countries.
This time it’s further to the south, with Chile’s beautiful Lake District and the highly active Villarrica Volcano around Pucón, and Argentina’s barren Patagonia, both prime spots.
Totality from the centreline of the path of totality will last for 2 minutes and 8 seconds throughout the continent, so the only decision to be made is about where the highest chance of clear skies are.
Argentina will have a higher chance of clear skies.
If you’ve ever wanted to see South America, this would be a good time to go; as well as being in summer, it’s the last ‘easy’ eclipse for a few years; the following total solar eclipse on 4 December 2021, is in cold, cloudy and incredibly expensive-to-reach Antarctica, there is no totality in 2022, and in 2023 there’s only a super-short total solar eclipse in a remote part of Western Australia.
As a bonus for those camping out in Chile or Argentina, the Geminid meteor shower peaks the night before a lunchtime totality.