Do other planets have the same chemical isotopes?

Thanks to Xander Byrne for the answer!

James - Elements from the periodic table are ordered and defined by the number of protons in each of their atoms. This is the atomic number. For Carbon, that’s 6. But some atoms vary in the number of neutrons bound up with the protons in their nuclei. These variants are called isotopes, and while isotopes of the same element will share the same atomic number, they have different atomic masses. As you rightly identify, Pamela, carbon 12 (6 protons, 6 neutrons) and the rarer carbon 13 (6 protons, 7 neutrons) are the stable isotopes here on Earth, meaning that the nuclear force binding together the atoms is strong and so they stick around. But why are they distributed in that 99:1 ratio and, to your question Pamela, what about on other planets? Do we see a similar abundance of these isotopes? Here’s Xander Byrne from the University of Cambridge’s Institute of Astronomy…  

Xander - The short answer is yes! Carbon is made in stars by nuclear fusion, and nuclear fusion has this quirk where odd-numbered isotopes like carbon-13 are generally a lot harder to make than even-numbered isotopes like carbon-12. And because the laws of nuclear physics seem to be the same everywhere in the Universe, you'll always have a lot more carbon-12 than -13. If you give me a lump of coal and ask me to take out all of the carbon-13, it's actually very difficult, because chemically, different isotopes behave almost identically, because fundamentally they're still the same element. They faced a very similar problem in the Manhattan project, because to build a nuclear bomb, you can't just use any old uranium, you need uranium-235, but 99% of naturally-occurring uranium is 238, so they had to come up with all sorts of clever ways of "enriching" it, to get the isotope that they wanted.

James -  Remember. the only difference between isotopes is their mass: carbon-13 is a little bit heavier than carbon-12, and this slight difference has big consequences…

Xander - That’s right. It makes carbon 13 VERY slightly lazier - meaning it doesn't react as often. So when plants photosynthesise, taking CO2 out of the atmosphere, they preferentially take in molecules with carbon-12, and as a result, living things have even less carbon-13 than is in the atmosphere. In 2022, the Curiosity rover analysed some of the rocks in a crater on Mars, and found barely any carbon-13, which got people wondering: could this be a signature of life on Mars? But life isn't the only thing which can cause this isotope fractionation; another possibility is that it's just the way UV light from the Sun interacts with the CO2 in the atmosphere, and that would also account for this signature. What's really exciting is that we're finally able to look at isotope ratios in planets outside our Solar System. There was a study last year looking at a planet called VHS 1256b,
and because different isotopes absorb slightly different colours of light, by looking at the planet we can measure how much of each isotope there is. They found that rather than being only 1% carbon-13, this planet had about 1.5%. Now that might not sound like a huge difference, but that actually tells us a lot about the different processes that were going on when this planet was forming, and the fact that the isotope ratio is slightly different from the Earth suggests that other planets might form in very different ways than we did.