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 -    • The discovery of the first exoplanet  | Th...  
My previous video on the Habitable Worlds Observatory -    • Can we take a picture of an Earth-like pla...  
My previous video on zodiacal dust -    • How fast does the Sun orbit the Milky Way?...  
My previous video on the closest exoplanets to Earth -    • Every "closest EXOPLANET to Earth" from 19...  

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

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👩🏽‍💻 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