Finding exoplanets: the life and death of a hot Jupiter

Astronomers know of more than 6,000 planets around other stars, and fewer than 100 of them were discovered by taking their picture. So how do you find a planet you can't see? And how can you tell that one of them is slowly spiralling in towards its star? Part 1 draws the methods. A planet crossing its star dims it slightly: a transit. A planet tugging its star back and forth makes the star's light shift bluer, then redder: radial velocity. Starlight passing through a planet's atmosphere carries the fingerprints of its molecules, and a second, shallower dip, when the planet slips behind its star, tells us roughly how hot its dayside is. Then two methods about to get much bigger: Gaia's next data release, planned for 2 December, and microlensing with NASA's Roman Space Telescope, once its survey begins. Part 2 is one hot Jupiter's life story, told with the same tools: a giant flung onto a stretched orbit (HD 80606 b looks like one in the making), tides rounding that orbit off, and then WASP-12b. Its transits arrive a little earlier each year, because its 26-hour orbit is shrinking by about 30 milliseconds a year. The cause is tides, not on the planet but on its star. It's the only case of a dying orbit that astronomers broadly agree on. Chapters 0:00 A planet whose year is shrinking 0:28 More than 6,000 planets, few photographed 0:57 Method one: the dip (transits) 1:39 Method two: the wobble (radial velocity) 2:24 Starlight through an atmosphere 3:06 The other dip: secondary eclipses 3:45 Coming soon: Gaia and Roman 4:59 Part 2: hot Jupiters 5:26 The kick: HD 80606 b 6:31 The clock: transits arriving early 7:37 The lagging bulge 8:33 How long it has 9:12 Do stars swallow planets? Sources NASA Exoplanet Archive, planet counts by method (as of 8 Oct 2026; updates weekly): https://exoplanetarchive.ipac.caltech... Winn, Transits and Occultations (2010): https://arxiv.org/abs/1001.2010 Eggenberger and Udry, Doppler spectroscopy (2009): https://arxiv.org/abs/0904.0415 Gapp et al., WASP-121 b's morning and evening sides (Nature Astronomy, 2026): https://doi.org/10.1038/s41550-026-02... Coy et al., an atmosphere on HD 3167 b (ApJ Letters, 2026): https://doi.org/10.3847/2041-8213/ae7f23 ESA, Gaia DR4: https://www.cosmos.esa.int/web/gaia/dr4 Lammers and Winn, Gaia's exoplanet yield (2025): https://arxiv.org/abs/2511.04673 NASA, Roman's Galactic Bulge Time-Domain Survey: https://science.nasa.gov/mission/roma... Dawson and Johnson, Origins of Hot Jupiters (2018): https://arxiv.org/abs/1801.06117 Pont et al., the HD 80606 system (2009): https://arxiv.org/abs/0906.5605 Yee et al., The Orbit of WASP-12b Is Decaying (2020): https://doi.org/10.3847/2041-8213/ab5c16 Wong et al., TESS Revisits WASP-12 (2022): https://arxiv.org/abs/2201.08370 Ogilvie, Tidal Dissipation in Stars and Giant Planets (2014): https://arxiv.org/abs/1406.2207 Antonetti and Goodman, Roche limits and WASP-12b (2021): https://arxiv.org/abs/2108.01675 Adams et al., Doomed Worlds I (2024): https://arxiv.org/abs/2404.07339 Winn and Stefansson, Orbital decay candidates reconsidered (2025): https://arxiv.org/abs/2510.05229 Rathsam et al., planet engulfment in HD 129171 (A&A, 2026): https://arxiv.org/abs/2606.05934 NASA JPL, lunar laser ranging and the receding Moon: https://www.jpl.nasa.gov/news/the-apo... The drawings are schematic: the dips, the star's wobble and the tidal bulge are hugely exaggerated, and the spiral is time-compressed. "About three million years" is a decay timescale, not a countdown: the time WASP-12b has left is probably less, and it may be torn apart before it reaches its star. Gaia's date and planet count are a plan and a forecast. Credits Music: "Clockwork" created in Strudel.cc and rendered via MIDI in Reaper Voice and sound effects created in ElevenLabs Typeface: Jost by Owen Earl (SIL Open Font License) Data: WASP-12b transit times from Yee et al. (2020) via CDS VizieR; HD 80606 b's orbit from the NASA Exoplanet Archive Listen to the soundtrack The original music from this video is on SoundCloud:   / clockwork   #Exoplanets #Astronomy #Space #Physics