La Palma - Gateway to the Universe

On the volcanic peaks of La Palma, revolutionary new telescopes and cutting-edge technology are opening a new chapter in our exploration of space. High above the clouds, The Sky at Night team meet the scientists uncovering clues to the universe's greatest mysteries. Hunting for cosmic collisions that forge the gold in your wedding ring, capturing gamma rays from giant black holes and exploding stars, and seeking out elusive ‘dark matter’, their discoveries will change the way we look at the cosmos forever.

The team begin their La Palma adventure with the Cherenkov Telescope Array Observatory, or CTAO. Chris Lintott meets this mega-project’s director general, Dr Stuart McMuldroch, the day after its inauguration, and what he reveals is staggering. Built to detect the most powerful electromagnetic radiation – gamma rays – the CTAO will be able to capture particles with 150 trillion times the energy of visible light. And it does so not by looking far out into space but by focusing just a few kilometres up.

Watching for fast, faint flashes of blue Cherenkov light made by gamma rays striking atoms in our atmosphere and then tracking the trajectories of the gamma rays back into space, the CTAO will uncover the secrets of some of the most exotic and violent environments in the cosmos – the mouths of huge black holes and exploding stellar giants. Most excitingly, it will answer questions we haven’t yet even thought to ask.

Back in the UK, Maggie Aderin travels to the University of Warwick to see Dr Lisa Kelsey, an astrophysicist with a deep interest in ‘explosive transients’ – things that go BANG in the night sky. Lisa and her team are using data from a special robotic telescope at the La Palma observatory, GOTO-N, to search for these transients, and a vast network of citizen scientists are helping them do it.

Their 5,000 volunteers play a daily game of spot-the-difference, looking for changes in images taken by GOTO-N. And so far, they have discovered supernovae, variable stars and dwarf novae. But the hunt goes on for kilonovae. These cataclysmic mergers of neutron stars, the densest objects in the universe aside from black holes, produce elements heavier than a normal star can forge - from the gold in your wedding ring to the uranium powering our nuclear reactors.

Returning to La Palma and our guest presenter, Maggie Lieu, we’re off to the William Herschel Telescope with Prof Gavin Dalton. Gavin’s new instrument, WEAVE, is revolutionising the telescope’s capabilities and may help us to better understand one of the most mysterious substances in the cosmos.

The genius of WEAVE is its efficiency. One hundred kilometres of fibreoptic cables, ending in tiny prisms and placed precisely by robots, allow the instrument to observe and take spectra for up to 900 astronomical objects at once, inside and outside our galaxy simultaneously. It can run multiple projects at the same time, and one of these projects is a survey of five million stars in the Milky Way. As Maggie discovers, from the spectra generated by this survey, scientists will be able to get incredibly accurate speeds and motions of the stars, allowing them to spot any invisible gravitational attractors – the telltale sign of elusive dark matter.

At the Gran Telescopio Canarias, the largest optical telescope of its type in the world, Chris gets a guided tour from Prof Vikram Dhillon. He is there to see how a high-speed camera, HiPERCAM, is opening up new possibilities and new avenues of discovery in astronomy.

Mounted on its giant telescope, the 10.4 metre mirror collects huge amounts of light, allowing the camera to take up to 1,000 exposures per second. It can accurately observe some of the fastest moving objects in the night sky, from binary stars orbiting each other, to spinning black holes, and rapidly occulting dwarf planets. And the discoveries are mind-blowing.

With decades of heritage and new technology coming online all the time, the Roque de los Muchachos Observatory is surely one of the world’s most important hubs for space science, allowing us to expand the horizon of our knowledge of the cosmos. And from the beginning, British scientists have been heavily involved, something that continues to this day. Discoveries and breakthroughs are coming thick and fast. And, most importantly, when you look up from the mountain peak at the night sky, it takes your breath away.