The Astronomer Royal on alien oceans | with Michele Dougherty

The Royal Institution

The Royal Institution

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Could there be oceans (and even life) hiding beneath the icy surfaces of the moons of Jupiter and Saturn?

For most of the history of planetary science, the search for habitable worlds focused on planets close to the Sun, where surface water can stay liquid. But data from NASA's Cassini spacecraft at Saturn and the Galileo spacecraft at Jupiter has overturned that assumption, revealing that several icy moons may be hiding vast oceans of liquid water beneath their frozen crusts.

In this Discourse, Michele Dougherty — the first female Astronomer Royal — takes us through the Cassini mission's most extraordinary discovery: a plume of water vapour erupting from the south pole of Saturn's tiny moon Enceladus, and what it revealed about the possibility of life beyond Earth. She then looks ahead to ESA's JUICE mission, launched in 2023, which is now on its way to spend years studying Jupiter's giant moons Ganymede, Callisto and Europa — all suspected to hide oceans of their own.

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Chapters:
00:00 Introduction: Saturn, Jupiter and a Hidden Moon
02:18 Inside the Cassini Spacecraft
04:24 How Scientists Measure a Magnetic Field
06:16 Saturn's Rings and a Mysterious Moon
07:38 Enceladus: Too Young to Be True
09:28 Cassini's First Flybys of Enceladus
14:27 The Gamble: Flying Closer
16:27 Discovery: A Plume from the South Pole
18:52 The Ingredients for Life
19:52 Jupiter's Moons: Clues from Galileo
22:29 The Case for a New Mission to Jupiter
24:33 Building the JUICE Spacecraft
26:23 Building Instruments Through Lockdown
30:22 Launch from French Guiana
34:54 The Long Journey to Jupiter (2023–2031)
37:08 Ganymede: The Moon with Its Own Magnetic Field
39:08 Callisto, Europa and the Search for Oceans
44:40 400 Years of Icy Moon Discovery
46:23 Cassini's Grand Finale
51:52 The End of an Icon
53:40 NASA's Farewell Film
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About the speaker:
Michele Dougherty is Professor of Space Physics at Imperial College London. In 2025 she was named Astronomer Royal — the first woman to hold the position since it was created in 1675. Her research centres on planetary magnetospheres and atmospheric composition. She is a Principal Investigator on NASA's Cassini mission at Saturn and on ESA's JUICE mission, which will place the first spacecraft in orbit around a moon other than our own, Jupiter's Ganymede. She is Executive Chair of the Science and Technology Facilities Council, a Fellow of the Royal Society, was awarded the Gold Medal of the Royal Astronomical Society, and was made CBE in the 2018 New Year Honours.
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This was filmed at the Royal Institution on the 24th of July 2026.
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A note on Ri Discourses: Since 1825, Discourses have been one of the Ri's oldest and most prestigious lecture series, hosting the likes of Michael Faraday, JJ Thomson and generations of leading scientists sharing new discoveries with a public audience for the first time.
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#RoyalInstitution #Saturn #Jupiter #Enceladus #JUICE #Cassini #SpaceScience #Astronomy
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