The Night People

As a boy The Champions was one of my favourite TV series. Their origins at the hands of a mysterious ancient civilisation on the Tibetan plateau, the super-powers, the benign but secretive Geneva-based Nemesis, the nuclear submarines, atom bombs, spies - all catnip to a geeky Cold War kid. No doubt Alexandra Bastedo also had some impact :-).

Talking Pictures TV are showing the Champions just now. I haven't seen most of those episodes since they were shown originally and it's great fun to watch them again, so many years after. Some of my childhood favourites look slow and amateurish when you see them again but The Champions stories are mostly still amusing, nicely imagined, well acted, brisk and very entertaining. There's a special frisson in reseeing those moments that have been lurking just below the surface in my memories (hmm... just how did The Champions help to shape my world view?).

We've just watched episode 23, The Night People. It was great fun and I learned something. The setting, a distinctly unhospitable Cornish village and its nearby gothic castle combined with the white-robed acolytes, white witch, corn dollies with pins stuck in them to give it a distinct Hammer horror vibe. Even better that these elements were combined with uranium and atom bombs; a heady brew indeed.

Spoilers follow! Douglas Trennick, the ancestral lord of the manor is disappointed that his uranium mine is now worthless because the USSR and the Western powers have been signing test ban treaties and the like. So he sets out to forge and distribute a fake USA-UK agreement on developing nuclear weapons, hoping that the Russians will think it's real, the arms race will reignite and his uranium mine will be worth loads of money again. His eccentric ('white witch') wife offers some spooky window dressing that is used to keep inquisitive locals away. A hare-brained scheme at best but it makes a very amusing story. Mrs Trennick (Adrienne Corri) should have had a spin-off series of her own.

I thought a uranium mine in Cornwall was just one more of the story's more implausible ingredients but it turns out there was such a thing, South Terras mine near St Austell. It operated from 1870 to 1930. There is an excellent account here. Uranium was often a by-product of copper or tin mining but at South Terras there was a seam of uranium-containing minerals so it made sense to concentrate on the extraction of the substance. Uranium was valuable even before radioactivity was discovered, for instance in glass production. Later on radium was extracted from the mine, presumably for mostly medical purposes. It seems, however, to have suffered from poor management and the proposal of a new Anglo-French scheme in 1912 involved among the English sponsors "...the usual histrionic nobleman whose part it is to shed a phosphorescent lustre on the title page of a prospectus" - sounds like an ancestor of Douglas Trennick.

Uranium mining there ceased many decades go but the mine is still interesting. In a scientific article published in 2017 we learn that residual uranium has not leached away in the way that might have been expected, for chemical reasons that may help to prevent uranium seepage from other disused mines and nuclear installations.

How interesting to find this element in a Champions storyline. Was one of the scriptwriters from Cornwall?

Charged particles from the Sun

Last night people in the north of Scotland were treated to displays of the Northern Lights (aurora borealis). For this beautiful phenomenon, the further north you are the better - although it also helps that the north of Scotland is sparsely populated so there's very little light pollution. It was great to see them eulogised on BBC Breakfast this morning, by the weather forecaster Matt Taylor who also shared some images and videos on Twitter.

Why do I care? Well, I'm an astronomer so I'm interested in everything you see in the sky. Living in Scotland I have more chance than many to see the aurora with my own eyes and I have seen it on a few occasions, the first time in, maybe 1968 when my parents woke me to marvel at it (they knew their already geeky wee boy would be excited!). The spectacular glows, arcs that reached the zenith, were particularly memorable because the August sky was not yet dark - must have been a really big one. But since my research has focused on solar flares and phenomena of the Sun's outer atmosphere I also have a detailed, professional level interest in the drivers of the aurora. The outer atmospheres of both Sun and Earth involve gas in the state known as plasma, where many atoms are ionised and electric and magnetic forces play fundamental roles. Plasma physics underlies both topics and researchers in both fields can and do learn from each other.

One often hears people say, as Matt Taylor did this morning, that the aurora is caused by "charged particles from the Sun". This isn't quite right. Let me try to explain why not, and maybe what we could say if we just wanted to use a quick sentence.

In fact "charged particles" arrive at Earth from the Sun all the time. The solar wind is a steady flow of gas away from the Sun, out into the solar system. It's very tenuous gas but also at a very high temperature, in the region of a million degrees C. At these high temperatures, every collision between two atoms involves enough energy to ionise and the gas in the Sun's hot outer layers is almost completely ionised: the gas is made up of positively charged ions and negative electrons. The gas is still neutral, overall, but its constituents are indeed "charged particles". It's a plasma. One of the many remarkable features of a plasma is that gas and magnetic field become tied together. Moving gas can carry magnetic field with it, and changes in magnetic fields can make the gas move. This is quite different from the situation, e.g. in your sitting room where the air around you is made up of electrically neutral atoms and waving a bar magnet about doesn't make it move. So the solar wind has an effect on the magnetic field near Earth, squashing it up on the day side and dragging it out into a long tail, the magnetotail on the night side.

However this happens in a fairly steady way all the time but we don't see aurora all the time (actually there is a faint, steady glow called the polar aurora but that's only visible further north than the UK and it's not what we recognise as aurora borealis). Displays of the aurora are driven by some disturbance in the solar wind. There are a couple of ways this can happen. The solar wind may be either "fast" or "slow", travelling at about 800 or 400 km per second respectively, depending on what's happening magnetically where it leaves the Sun. Crossing a boundary between fast and slow wind is one occurrence that can trigger the aurora. The Sun's outer atmosphere also sees explosive phenomena, Coronal Mass Ejections (CME's), that send clouds of magnetised gas out into space. The picture at left, from the LASCO experiment on the ESA/NASA SoHO spacecraft, shows one particular CME leaving the Sun on 2 December 2002. Aurorae can also be triggered if a CME arrives at Earth so it's useful to keep an eye on the Sun for early warning this might happen - see e.g. the Space Influences Data Analysis Center in Brussels.

Either of these sorts of disturbances can trigger sudden readjustments of the magnetic field in space near the Earth (in the region called the magnetosphere where the behaviour of the plasma is dominated by magnetic forces). Rapidly changing magnetic fields mean strong electric fields which accelerate electrons in the magnetosphere to high energies. They follow the magnetic field lines and hit the atoms of the upper atmosphere above the polar regions, causing the glow of the aurora. So the actual energetic particles, that are responsile for the glows of the aurora, have been energised close to the Earth, even although the disturbances in the solar wind that caused them in the first place started at the Sun.

People studying the aurora particularly with spacecraft, exploring the relevant regions of space and actually measuring the particles, electric and magnetic fields, have known all this for a few decades now. I've seen Lucie Green, for instance, speak about the aurora on TV and give a clear and correct description of what happens. I'm slightly surprised the "charged particles from the Sun" words are still widely used. I know there isn't always time to delve into the ins and outs and it's great to see this beautiful science discussed alongside all the other news of the day, and indeed the weather forecast. Saying "charged particles accelerated in Earth's magnetic fields when disturbances arrive from the Sun" would be slightly longer, OK, but also more correct.

Meteors are better than planets

The days are shortening and our thoughts turn to dark skies. August sees one of the highlights of the astronomical calendar, the Perseid meteor shower. Each year as the Earth crosses the path of comet 109P/Swift-Tuttle our skies are decorated by many shooting stars, 10s per hour if you're somewhere dark. The night of 12/13 August looks set to see the most meteors but it's well worth looking on the couple of nights either side of this. To see a meteor every minute or two, over a couple of hours, is something memorable and thrilling, well worth sacrificing a little sleep and warmth for.

Because they're in the foreground, meteors, like planets, move against the background of the stars. You need to watch the planets over days or weeks to become aware of this whereas a meteor is over and done with in a second or two, at most. The planets are completely reliable and predictable in their apparitions whereas a single meteor, a grain of cosmic sand heated briefly to destruction, appears without warning and is never seen again.

Meteors are better than planets. Planets shine in the night sky only because they reflect light that has come in the first place from the Sun. They have no light of their own. Remove the Sun - admittedly difficult - and they would just be cold, dark orbs. Brief though its luminous life is, the brilliance of the meteor is its own. OK, that's a flippant view but I think defensible at least from the point of somebody looking at the night sky with the naked eye.

A typical, bright but not dazzling meteor is a speck of rock about the size of a grain of sand. Travelling for the first time in Earth's atmosphere, at a speed of a few 10s of kms per second, it heats up to about 1800°C, leaves a tail of brightly glowing vapour - the "meteor" that we see - and disintegrates. Even when Earth crosses the path of a comet these particles are few and far between. Could they ever be so numerous that the whole of the sky was bright?

In fact this may have been the state of affairs 65 milion years ago, immediately after the Chicxulub asteroid impact that probably killed off the dinosaurs. An asteroid 10 to 15 km across crashed into the Gulf of Mexico causing global devastation. The resulting explosion threw debris, rocks and dust, high into the atmosphere. As it fell back it heated up as individual meteors do, but involving so many more particles of all sizes that the whole of the sky would have glowed fiercely. The incandescent sky triggered forest fires all across the globe and the soot from these has been identified at the K-T boundary, the layer in the rocks corresponding to the time of this event.

Such events were common in the early history of the Earth and the other planets. The first half billion or so years of Earth history is called the Hadean eon - "hellish"! Those worlds unmodified by an atmosphere, water, etc. - like our own Moon - still show the scars in the many impact craters that dot their surfaces. Meteors and fireballs lit up the sky all the time and Chixculub type events would have occurred over and over again, albeit on a world looking very different from its present state.

Nowadays things are quiet. A meteor shower is pretty but not threatening. The vast majority of the rocky bodies flying around in the earliest times have either been incorporated into the bodies of the planets or expelled to the far edges of the solar system, to the Oort cloud. None of the known Near-Earth Asteroids or Comets poses a threat. We're living in a time of tranquility when it's been possible for us to emerge and get on with what we want to do. The biggest threat to the planet now is ourselves.

Hoping for clear skies this week!

Titanium

I have decided I need a new, lighter bike so I can go further without getting knackered, and also go faster so I can still be home for teatime. The obvious choice nowadays, money allowing, is a carbon fibre bike. Many of these weigh 3 kg less than the cheap aluminium bike I've been riding for, I guess 15 years. But I also looked sideways at bikes made of titanium, Ti. Lighter and stronger than steel, titanium offers an attractive if pricey material for bike frames. Titanium metal is highly reactive but it very rapidly acquires a surface layer of titanium oxide, TiO, which then protects the metal beneath. Hence there's no need to paint them and titanium bikes have a metallic, science-fiction look (see e.g. the IMAX film theatre and the other buildings of the Glasgow Science Centre).

Where does titanium come from? Well, we extract it from titanium-containing minerals. But how does it come to exist in the Universe at all? A crazy question at first sight but such questions do have well-defined answers. In the case of titanium we know that it is created in the briefly occurring, intense conditions of a supernova, the cosmic-scale explosion that marks the end of the life of a star much more massive than the Sun; in so-called explosive nucleosynthesis. A supernova happens somewhere in the Milky Way every 100 years or so. Over the history of the Universe this is often enough to account for the presence in nature of many of the chemical elements. Titanium - and many other things - would have been much less abundant when the galaxy was, say a tenth of its present age.

Just outside Newton Mearns yesterday my eye was caught by another rider on the other side of the road. His bike had a distinctive metallic frame. "Ooh, titanium bike", I thought. Solar physicist that I am, my next thought was of sunspots, dark patches on the surface of the Sun threaded by strong magnetic fields. They appear dark because they are 2000° cooler than the surrounding solar surface. Molecules are uncommon in most of the Sun because of the ubiquitous high temperatures but in the cooler conditions of sunspots they can persist more easily. On visits to Meudon Observatory in the 1980s and 1990s I made the acquaintance of Paskal Sotirovski, a remarkable personality who specialised in studies of molecules in the Sun's atmosphere, particularly in sunspots. TiO is present in sunspots and the study of its spectrum lines, pursued in detail by Paskal and others, tells us more about conditions in these regions.

While the remnants of DACE were part of the School of Education I taught an elective, "liberal arts" Astronomy course for students learning to be primary school teachers. Some were already enthusiastically interested in science; others would have been just as happy, or not, in other electives on Latin or History of Art. As a preamble to talking about the Sun's interior and nuclear fusion I handed out copies of the periodic table, asking "what's your favourite element?" One girl didn't hesitate: Titanium!

"Stumbling on Happiness"

I'm reading Stumbling on Happiness by Daniel Gilbert. The wonderful Maria Popova put me on to it, with this quote: "human beings are works in progress that mistakenly think they're finished". It gives an accessible, breezy account of the Psychology of happiness, rooted firmly in empirical science - not at all a self-help book.

At the end of Chapter 9 he gives a very condensed summary of some key points:

We've seen how difficult it is to predict accurately our emotional reactions to future events because it is difficult to imagine them as they will happen, and difficult to imagine how we'll think about them once they do. Throughout this book I've compared imagination to perception and memory, and I've tried to convince you that foresight is just as fallible as hindsight and eyesight.

When I worked on mature student Access I was often struck, at the end of the year, by the transformative effects for the students. They stood a teeny bit straighter. There was a little gleam in their eyes. They had a new air of confidence and direction. Helping to make this happen felt like a privilege. Now I'd like to understand a little better what I was seeing.

I haven't finished Stumbling on Happiness yet. I don't know yet if there is a surprising punchline, or indeed if it will help me understand what I saw on Access but I do think that comment about "works in progress" is at the heart of it, that it is profoundly, deeply human to learn and change through learning, a sort of growth possible for the person even in adulthood, an expression of our relationship with time.