The Sky at Night TV show, past, present and future
Inside The Sky at Night
As November’s Sky at Night looks at the Universe’s mysteries, Emma Chapman tells us how radio astronomy got her hooked on solving them
Few people dream of being a radio astronomer. Many of the origin stories of my colleagues involve frosty nights learning the constellations or else convey the sublime nature of seeing the rings of Saturn for the first time. It’s less common to hear of a childhood calibrating an antenna to listen to the pings of meteors or the hiss of solar flares. Indeed, I cannot offer that story either. I grew up wanting to be an Egyptologist who spent her days brushing away sand from hidden treasures and decoding ancient messages.
Having read every archeological book in the library, my teenaged eyes had wandered to the popular science shelf. Until then, I had enjoyed physics, but I didn’t know that the subject still held any real mystery and wonder. I had so many new questions that, rather last minute, I changed my career path. It was the history of the Universe that fascinated me most of all, especially when I learned we could observe the light from the early Universe. I had found the ultimate archeological ruins.
When I was assigned a PhD project to search for the first stars using radio telescopes, I had mixed feelings. I had never heard of anybody searching for the first stars and I was excited to hear of the unexplored first billion years in our timeline. The primordial Universe contained only hydrogen and helium, and without the cooling effects of heavier elements the first stars formed on the order of one hundred solar masses. The collapsing force of such a mass of gas meant that fusion progressed quickly. Within only tens of millions of years, this generation of stars became extinct in brilliantly energetic supernovae, seeding their environment with the heavier elemental products of fusion. The first stars are an extinct species: they cannot form in the polluted space of today. But they left their messages in the light that is only just reaching us now.
Sleuthing for signals
The first stars and baby black holes were mine for the uncovering, but I needed a tool not usually in an archeologist’s (or most astronomers’) tool belt: a radio antenna. Not quite the clean rooms and rocket launches of NASA, or the clear nights observing up mountains in Hawaii that I had envisaged, but the mystery was too great for me not to pursue. Optical astronomy is, of course, far more intuitive to us. We have two little telescopes sitting in our head through which we view the world, but only in optical wavelengths. Light is a spectrum, comprising a huge range of wavelengths, of which the optical spectrum occupies only a tiny sliver. Radio light can help us look at the Universe differently. By placing 131,000 deceptively simple Christmas tree-like metal antennas in the Western Australian desert (as well as an additional 200 dishes in South Africa) to build a radio telescope called the Square Kilometre Array, we are planning to stream the home movie of this missing era, picking up signals from the furthest reaches of space to finally uncover the stars that started it all.
When I was a teenager, I dreamt of walking through the sands of Egypt. And now, yes my boots are dusty with sand, but it is from visiting the remote radio observatories that have given us a window back to the very beginning. I am no longer searching for what might be hidden under my feet. Instead, I am looking up: a historian armed with a telescope.
Emma Chapman is a Royal Society research fellow based at the University of Nottingham and author of First Light.
Looking back: The Sky at Night
15 December 1976
When the December 1976 episode of The Sky at Night was broadcast, Venus was shining brilliantly in the evening sky. Our understanding of the cloud-covered planet had changed dramatically by the middle of the 20th century and so Patrick Moore took this episode as an opportunity to have a closer look at Venus.
In 1956, radio measurements of the Venusian atmosphere suggested the planet’s temperature could be several hundred degrees higher than previously thought – and indeed the surface was later found to be 475°C, with a pressure a crushing 92 times that of Earth.
The first real examination of the planet came from the Soviet Venera programme, 16 missions that explored the planet from 1961 to 1984.
Some of these were orbital, their fly-by spacecraft using radar to pierce the clouds and map out the planet’s surface. These revealed a craggy and cratered landscape, covered in valleys, mountains and volcanoes. But it was the landing missions that really gave us a close-up view of Venus. The thick atmosphere meant it was possible to float to the surface on a parachute – the tricky part was building a craft that could survive the hellish atmosphere long enough to make it. However, several of the Venera missions managed the journey and in October 1975 Venera 9 sent back the first-ever pictures from the planet’s surface, revealing the boulder-strewn landscape, dimly-lit beneath the clouds.
First Contact: An Alien Encounter
There’s no episode of The Sky at Night in December, but instead you can catch up with this ‘21st-century War of the Worlds’, which is available to watch on the BBC iPlayer. First Contact is a feature-length drama documentary imagining what might happen if humanity detected evidence of an extraterrestrial civilisation. Based on interviews with SETI expert Jill Tarter, the drama attempts to answer one of the greatest questions facing humanity: what happens if we find out we are not alone?
www.bbc.co.uk/programmes/m001ctnr
