Uploaded June 2025 | Updated September 2026, 2 weeks ago
AD | Join me in reading Nautilus by heading to joinnautilus.com/drbecky where you can get 15% off a membership to Nautilus, perfect for any science enthusiast. | Is there life on Mars? It’s a BIG question that David Bowie has been asking for a long time! So the majority of missions and rovers that get sent to Mars have a focus on figuring out if life currently exists on Mars, or more likely (we think), whether life once existed on Mars in the past but no longer. From the rovers of the past like Opportunity, to the rovers of the future like the Rosalind Franklin rover (ESA’s ExoMars mission), and to Perseverance and Curiosity rovers currently operating on Mars. The Perserverance rover is collecting rock samples and leaving them on the surface for a future Mars mission to collect and return to Earth. But why? Why do we need to return samples to Earth to test for this when the rovers are essentially scientific lab instruments on wheels? Well a few years ago this paper by Azua-Bustos and collaborators was published who used the techniques available to current and planned Mars rovers to test whether they could find signs of life in a sample of rock from Earth in the Atacama desert. And spoiler alert: they couldn’t...
Azua-Bustos et al. (2025) - nature.com/articles/s41467-023-36172-1
More on the SOLID-LDChip detector - cab.inta-csic.es/en/proyectos/solid
More on the Martian rock samples collected by Perseverance - science.nasa.gov/mission/mars-2020-perseverance/mars-rock-samples
My previous video on cuts to NASA funding including the Mars Sample Return mission - youtube.com/watch?v=si6paqM2_ug
00:00 Introduction
03:00 Why was the Atacama Desert chosen for the experiment?
05:15 What kind of tests were done?
08:40 What can Mars rover instruments detect in the Atacama Desert?
14:11 Bloopers
Video filmed on a Sony ⍺7 IV
Video edited by Martino Gasparrini: fiverr.com/mgs_editing
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📚 My new book, "A Brief History of Black Holes", out NOW in hardback, paperback, e-book and audiobook (which I narrated myself!): lnk.to/DrBecky
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👕 My new merch, including JWST designs, are available here (with worldwide shipping!): dr-becky.teemill.com
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🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive
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🔔 Don't forget to subscribe and click the little bell icon to be notified when I post a new video!
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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.
drbecky.uk.com
AD | Join me in reading Nautilus by heading to joinnautilus.com/drbecky where you can get 15% off a membership to Nautilus, perfect for any science enthusiast. | Is there life on Mars? It’s a BIG question that David Bowie has been asking for a long time! So the majority of missions and rovers that get sent to Mars have a focus on figuring out if life currently exists on Mars, or more likely (we think), whether life once existed on Mars in the past but no longer. From the rovers of the past like Opportunity, to the rovers of the future like the Rosalind Franklin rover (ESA’s ExoMars mission), and to Perseverance and Curiosity rovers currently operating on Mars. The Perserverance rover is collecting rock samples and leaving them on the surface for a future Mars mission to collect and return to Earth. But why? Why do we need to return samples to Earth to test for this when the rovers are essentially scientific lab instruments on wheels? Well a few years ago this paper by Azua-Bustos and collaborators was published who used the techniques available to current and planned Mars rovers to test whether they could find signs of life in a sample of rock from Earth in the Atacama desert. And spoiler alert: they couldn’t...
Azua-Bustos et al. (2025) - nature.com/articles/s41467-023-36172-1
More on the SOLID-LDChip detector - cab.inta-csic.es/en/proyectos/solid
More on the Martian rock samples collected by Perseverance - science.nasa.gov/mission/mars-2020-perseverance/mars-rock-samples
My previous video on cuts to NASA funding including the Mars Sample Return mission - youtube.com/watch?v=si6paqM2_ug
00:00 Introduction
03:00 Why was the Atacama Desert chosen for the experiment?
05:15 What kind of tests were done?
08:40 What can Mars rover instruments detect in the Atacama Desert?
14:11 Bloopers
Video filmed on a Sony ⍺7 IV
Video edited by Martino Gasparrini: fiverr.com/mgs_editing
---
📚 My new book, "A Brief History of Black Holes", out NOW in hardback, paperback, e-book and audiobook (which I narrated myself!): lnk.to/DrBecky
---
👕 My new merch, including JWST designs, are available here (with worldwide shipping!): 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.
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
🔔 Dont forget to subscribe and click the little bell icon to be notified when I post a new video!
👩🏽💻 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)



