Astronomical words

eclipse

On Monday (8th April), there was a total solar eclipse. Sadly you could only see this if you were in North America – here in the UK it was only a partial (described as a ‘small grazing’ on one website I saw). I didn’t manage to see any of it, but it did get me wondering – where does the word ‘eclipse’ come from?

These days, ‘eclipse’ refers to the partial or complete obscuring of one celestial body by another, or the shadow cast by one celestial body on to another. We also use it metaphorically to describe someone or something being overshadowed by something else.

‘Eclipse’ comes from ancient Greek, from ‘ekleipsis’, meaning ‘an abandonment’ or ‘a failing’, to reflect those poor old ancient Greekies being abandoned or failed by the sun or moon. Over time, the word was adopted into Latin as ‘eclipsis’, then into Old French as ‘eclipse’, before finally making it to Middle English as, you’ve guessed it, ‘eclipse’.

Eclipses have long been viewed with some superstition, and there have been various odd things that have happened during them. Here are just a few.

  • The Battle of the Eclipse (585 BCE): One of the earliest recorded instances of an eclipse influencing human affairs happened during this battle between the Lydians and the Medes in what’s now Turkey. According to the ancient Greek historian Herodotus, there was a total solar eclipse in the middle of the fighting, which both sides took as a sign to stop battling and make peace. So that’s nice. On the flipside, during the Battle of Muye (c. 1046 BCE) in ancient China, a total solar eclipse terrified the soldiers, causing panic on both sides. It’s thought that one side (the Zhou) used this to their advantage to boost morale, claiming it was some sort of divine favour, and went on to defeat the Shang dynasty.

  • The death of Henry I (1133): The OG Hazza died from eating a shitload of lampreys, a type of jawless fish (yum), during a feast. His death also coincided with a total solar eclipse which many people took as a portent of his impending demise, or as a sign of divine displeasure at all those poor fish he ate.

  • The New Madrid Earthquakes (1811–1812): This was a series of powerful earthquakes – in fact, some of the most powerful ever recorded in the contiguous United States (I had to look up what that means – it’s all the states that are connected to each other, i.e. the 48 adjoining states on the North American continent – so it doesn’t include Alaska and Hawaii). The earthquakes happened during a time of heightened celestial activity, including multiple solar and lunar eclipses. There’s no scientific connection here but it must have brown trousers all round for anyone in the middle of them.

astrobleme

Photo by Jimmy Conover on Unsplash.

Photo by Jimmy Conover on Unsplash.

An astrobleme is the name given to a site that’s been hit by a meteorite. Or, to put it in more science-y terms, an ‘impact structure’. This isn’t to be confused with an ‘impact crater’ which is, well, just the hole-y bit – the impact structure includes all the deformed bedrock and sediment that’s underneath the hole (assuming I’ve understood Wikipedia correctly of course).

I like the word ‘astrobleme’ because it’s super literal. Its etymology translates as ‘star wound’ – ‘astron’ is Greek for star, and ‘bleme’ (also Greek) means ‘throw of a missile; wound caused by a missile’. It was coined by an American geologist called Robert S Dietz (1914–1995). His most notable feat was identifying the Sudbury Basin (Sudbury in Ontario, Canada, not the one in Suffolk which is just up the road from where I type this) as an ancient astrobleme – the second (or third, depending on which website you look at) biggest in the world.

But what’s the biggest, I hear you cry? Well, that honour belongs to the Vredefort crater in South Africa. It’s just over 300km (186.4 miles in old money) across. That means that the meteor that hit it was over 15km (9.3 miles) in diameter. Don’t panic though – it happened a VERY long time ago in the Paleoproterozoic Era which was between 2,500 and 1,600 million years ago.

The Vrefort crater has competition for the top spot from the Wilkes Land crater, which is underneath the ice caps in Antarctica and is as yet unverified. If it is an astrobleme then it’s a massive 480 km (300 miles) across. That means that the meteorite that caused it was at least 55km (34.5 miles) in diameter, which is four or five times wider than the Chicxulub impactor (good name for a band) AKA the one that killed all the dinosaurs, and also three-quarters of all the plant and animal species on Earth. Fuck.