The things we DON'T KNOW about EXOPLANETS

The things we don’t know are what drives science forward. A lack of knowledge, of not knowing the answer to a question is what pushes scientists to get more data, or design a new experiment. And in the case of astrophysics, those new experiments are often entirely new observatories, either on the ground or up in space, the design of which is driven by the gaps in our knowledge. So I love it when a paper is published summarising all the things we don’t yet know about a topic, and this month we saw that for exoplanet research. Exoplanets are planets orbiting other stars in our galaxy the Milky Way, we currently know of just under 6000 of them, some being the only planet around a star known, and some being in multiple planet systems just like the solar system. We’ve found everything from hot Jupiters close into their stars, to super-Earths that might be habitable since the first exoplanet was discovered in 1995. In this video I thought it would be fun to go quick fire through the 17 different knowledges gaps, the things we still don’t know, summarised in this paper by Stapelfeldt & Mamajek - to figure out what’s next for exoplanet science, including the search for life out there in the Universe.... Stapelfeldt & Mamajek (2025) - https://arxiv.org/pdf/2507.18665 My previous video on the history of exoplanet research - https://youtu.be/6_bJXZuREOA?si=tnQDDwZMnfssuf3N My previous video on the Habitable Worlds Observatory - https://youtu.be/z2JIkAPcdnU?si=1UMvyk5CwZl65Tl4 My previous video on zodiacal dust - https://youtu.be/noT8kkdl8hE?si=z4mUOR1CBF9su4vm My previous video on the closest exoplanets to Earth - https://www.youtube.com/watch?v=0QGAfyrEing 00:00 Introduction 01:30 Spectroscopic observations of the atmospheres of small exoplanets. 02:40 Modelling exoplanet atmospheres 03:20 Spectral signature retrieval 03:55 Planetary system architectures: occurrence rates for exoplanets of all sizes 04:40 Occurrence rates and uncertainties for temperate rocky planets 05:05 Yield estimation for exoplanet direct imaging missions 05:55 Intrinsic properties of known exoplanet host stars 06:30 Mitigating stellar jitter 06:55 Dynamical confirmation of exoplanet candidates 07:40 Observations and analyses of direct imaging targets 08:15 Understanding the abundance and distribution of exozodiacal dust 09:05 Measurements of accurate transiting planet radii 09:40 Properties of atoms, molecules and aerosols in exoplanet atmospheres 10:05 Exoplanet interior structure and material properties 10:30 Quantify and mitigate the impacts of stellar contamination 11:15 Complete the inventory of remotely observable exoplanet biosignatures 11:45 Understanding planet formation and disk properties 12:56 Bloopers --- 📚 My new book, "A Brief History of Black Holes", out NOW in hardback, paperback, e-book and audiobook (which I narrated myself!): http://lnk.to/DrBecky --- 👕 My new merch, including JWST designs, are available here (with worldwide shipping!): https://dr-becky.teemill.com/ --- 🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive --- 🔔 Don't forget to subscribe and click the little bell icon to be notified when I post a new video! --- 👩🏽‍💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford (Christ Church). I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars. http://drbecky.uk.com