Haven’t we been here before? One could wonder why, having presented Wonders of the Solar System (2010) and The Planets (2019), Professor Brian Cox would go back for another dip with the new five-part BBC documentary series Solar System.
It turns out – and it’s clear from the opening minutes of Solar System – that there was much still to see.
“One of the most important things is the new data: we tried to focus on the spacecraft that are there now – there’s more than 40 of them sending back new data and we have more data than ever before,” says Cox, leaning forward in his gaming chair at home in Battersea.
“Secondly, I suppose it’s natural to focus on planets and moons and the big spectacular-looking things, but quite a lot of this series is about the other stuff. Small worlds, tiny little places far away from the Sun that we hadn’t really spoken about before. But with the new space probes and space telescopes, we’re beginning to get pictures of these really odd things we didn’t know much about five, six, 10 years ago.”
Thus, we’re taken to the Kuiper Belt, the counterpart to the solar system’s main asteroid belt, out beyond Neptune, whose worlds have only opened up to us since Nasa’s New Horizons spacecraft got close to Pluto and its neighbours in 2015.
“Until we went to Pluto, we thought that would be just an inactive, cold thing, a long way from the Sun – and then we see there are glaciers flowing down valleys on this world, there are mountains of ice floating on nitrogen glaciers. Ridiculous place. Or Ceres, this interesting minor planet: the evidence that there may be water below the surface on that world is tremendously exciting, because on Earth, where you find water, you find life. We don’t know, of course – could life exist on a little world like that? – but, at least, the question is raised.”
Significantly, Solar System also spends a fair bit of time on Earth. It’s not a new device for Cox – or any space documentarian – to shoot in terrestrial landscapes that fit the theme, but here it’s not Cox sitting on a mountain musing about the ineffable nature of space-time, but something more nitty-gritty. The literal earth science of plate tectonics may, for example, explain why our world and Venus are such different places.
“Why doesn’t Venus have plate tectonics? We don’t know. Is it Earth that’s unusual or Venus that’s unusual?” says Cox. “If it’s Earth that’s unusual, then we begin to get more evidence that this place may be a very rare place in the wider universe. Maybe Venus is the way that rocky planets close to a star tend to be, with a runaway greenhouse effect, volcanoes not under control, because it doesn’t have plate tectonics.
“The technical name is comparative planetology – the idea that really what nature has done is given us a laboratory and conducted different experiments on different worlds. That’s the way you learn in a science lab – you do different experiments, change things a bit, see what happens. That’s the way you learn about things. So treating the solar system like that, I think, is very valuable. That’s what this series tries to do.”
It’s a theme throughout. Cox explains that the difference between one of the Saturnian moons, Enceladus, and Earth’s Moon is analogous to that between a fresh egg and a boiled one – the former has a wobbly rotation because there’s something liquid sloshing around inside. The laws of thermodynamics also get a good going-over in the first episode, Ice Worlds.
“I’m always looking for a thread, and the thread that appeared in the first episode was this idea that really it’s a programme about thermodynamics. Any geology programme is about thermodynamics. The third episode was about atmospheres, but it became a love letter to chemistry. My director, Fleur Bone, has a PhD in chemistry and she’s always wanted to make a film about chemistry, and nobody would let her. But we very soon realised, almost on the first day, that this is a film about chemistry.”
Of course, viewers won’t necessarily sign up for a five-part science lesson. We do want to see images of strange, magical worlds and Solar System smoothly blends actual space photography with computer-generated landscapes. But are there times when Cox has to tell the artists to tone it down?
“We have a lot of scientific advisers, many of the people who actually worked on the missions, and what we did in this series, where possible, was either used photographs or we used the data, the topological data from the space probes, the radar maps and so on, to build a computer model of the landscapes. They’re visualisations of data, basically. There are a couple of places where you have to just imagine. But Mars and Venus, we have really detailed topological maps of those planets.”
One of the most intriguing observations comes from something far more humble than a space probe. As Cox explains, the path of the meteorite that fell around Winchcombe in the Cotswolds in 2021 was captured by multiple doorbell cameras.
“It’s such a cool little thing, that. For us here in the UK to start a film in this little place in the Cotswolds, because we’re usually in exotic landscapes in Iceland or Alaska, or wherever. But it’s one of the best-documented meteorite impacts on Earth, because it was in a residential area. And so because of that, the trajectory of this thing was calculable with great accuracy. It’s the modern world – if you get one of these things and everybody’s doorbell camera sees it, you can work out where it came from.”
Cox has his own history with space observation. In 1980, at the age of 12, he famously wrote to Nasa asking for images captured by the Voyager and Viking missions and has often said that receiving those photographs set him on the path to a career in physics. Solar System underlines that our view of the solar system has largely emerged during his lifetime.
“These are the only places in the universe that we’ve visited. Everything else you see through the light they emit, or the radio waves or whatever, but we’ve been to these places, so yeah, I think it gives the series a solidity. They’re mainly real photographs of real worlds. These worlds are linked to us, they influence how the Earth has evolved. It’s an interconnected system of worlds that influence each other and to understand our planet, you have to understand how these other worlds evolved, what they’ve done to us and what we’ve done to them.”
Are we, then, in a golden age of observations?
“We can never arrive at Neptune for the first time again, as we did in 1986 with Voyager 2. But the first images from Jupiter and Saturn were fly-bys and we’re putting orbiters around these worlds now. So I think we are undoubtedly in the golden age. On Mars, as well. Mars sample return is key. If life existed, or may still exist on Mars, we won’t prove that, even if we get a hint, until we get stuff back into laboratories here on Earth. And that should be, with a bit of luck, in a decade or so.”
Solar System begins on BBC Earth on November 21, 8.30pm.
