Uploaded March 2026 | Updated September 2026, 2 weeks ago
I am back! Back doing my research on supermassive black holes and back to making regular weekly astrophysics content for you as well. Back to “translating” the research my colleagues publish in a way that’s easier for people to understand. And I just want to say thanks to you all for sticking around while I went through my treatment; chemo and radiotherapy were not fun, but having that normalcy of making my Night Sky News videos each month, recapping the latest astronomy news was a lifeline for me, even if everything was done with just voiceover. My channel will be getting back to normal as we go through March and i cannot wait to see what the rest of 2026 brings, and what new astrophysics discoveries are just right around the corner. Make sure you’re subscribed so you don’t miss out!
👩🏽💻 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.
drbecky.uk.com
I am back! Back doing my research on supermassive black holes and back to making regular weekly astrophysics content for you as well. Back to “translating” the research my colleagues publish in a way that’s easier for people to understand. And I just want to say thanks to you all for sticking around while I went through my treatment; chemo and radiotherapy were not fun, but having that normalcy of making my Night Sky News videos each month, recapping the latest astronomy news was a lifeline for me, even if everything was done with just voiceover. My channel will be getting back to normal as we go through March and i cannot wait to see what the rest of 2026 brings, and what new astrophysics discoveries are just right around the corner. Make sure you’re subscribed so you don’t miss out!
👩🏽💻 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.
drbecky.uk.com








![How do we know there are 2 TRILLION galaxies in the Universe?
AD - To try everything Brilliant has to offer for free for 30 days visit https://brilliant.org/DrBecky and youll also get 20% off an annual premium subscription which gives you unlimited daily access to Brilliant. | How many galaxies are there out there in the Universe? Well our best estimate in 2026 is that there’s *at least* 2 trillion galaxies, islands of billions of stars just like our own Milky Way galaxy. But how do we actually know that? That’s far too big of a number for anyone to have gone out and literally done a count one by one [insert home alone count scene], so what do we do instead? Well in this video we’re going to dive in to how us astrophysicists get at this number, and we’re going to try and put that number into content, how big is 2 trillion really?
Conselice et al. (2016) - https://assets.science.nasa.gov/content/dam/science/missions/hubble/releases/2016/10/STScI-01EVSR313NHNAC17DF62MP9QV9.pdf
00:00 2 TRILLION galaxies
01:10 Complication 1: the observable Universe
02:40 Complication 2: which direction you look in?
04:31 Complication 3: which telescope you use
06:35 Complication 4: what counts as a galaxy?
08:31 How big is 2 trillion really?
Video filmed on a Sony ⍺7 IV
Video edited by Martino Gasparrini: https://www.fiverr.com/mgs_editing
📚 My 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 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
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👩🏽💻 Im 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 dont know. If youve ever wondered about something in space and couldnt 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 How do we know there are 2 TRILLION galaxies in the Universe?](https://i.ytimg.com/vi/ttsxKzWle00/mqdefault.jpg)

