Has JWST spotted a planet around our nearest Sun-like star?!

Our best chance of finding intelligent life out there in the universe that we even have a hope of communicating with is if there was life on a planet in orbit around the nearest star to Earth 4 light years away. That would still mean it would take 4 years for any message that we sent to get there and then another four years for their message to get back to us. That nearest star is the Alpha Centuri system of three stars. There are two sunlike stars, Alpha Centuri A and Alpha Centuri B, that orbit each other, plus the technically closest star to us, Proximus Centuri, a faint red dwarf star, which then orbits those two sunlike stars. Now, while there has been a lot of excitement around the two, possibly three planets that have been discovered in orbit around Proxima Centauri, it's looking less and less likely that planets around red dwarf stars will be able to host life. That's from our observations that other red dwarf stars out there in the universe, which have shown to give off incredibly intense X-ray flares of radiation that is harmful to life. at least as we know it anyway. But all hope is not yet lost because there are also those two sunlike stars in the same system just over four light years away. And as of yet, no planets have been found orbiting them. Or have they? Because the James Web Space Telescope has now taken a look. And we saw these two research papers published last month by Bikeman and Sangi and collaborators that claim to have found a candidate gas giant Jupiter-like exoplanet orbiting one of these sunlike stars, Alpha Centuri A, but it is only a candidate exoplanet for now. It is not a confirmed discovery of a planet. So, in this video, we're going to dive in and chat first about why it's so hard to find planets around our nearest stars. Then second talk about the discovery of this candidate planet with JST around Alpha Centauri A. And then finally chat about why it's only a candidate exoplanet. But before we dive into all of that, if you see a news story like this online, how do you know that it is legit? Because let's face it, if you search for news on JWST and Alpha Centuri, it is just a minefield of clickbait and misinformation. Thankfully, this is where Ground News comes in, the sponsor of this week's video. Thanks to Ground News, I can immediately see that this news story, JWT and Orbit Models Bolster gas giant candidate in Alpha Centuri A's habitable zone, has been covered by 46 different news sources from around the world, and that 86% of those sources have a high factuality rating. So immediately I know that this is a story that I can trust. I can then compare the coverage across the different news outlets as well with ground news. So I can see that Gizmodo went with if this planet is real it would break so many records whereas India today went with web telescope discovers giant new planet in solar system next to ours. It's great to have all of that coverage in one place cuz with one click glance I can just see like the main points of the story, but also I can see if some news outlets might be sensationalizing the story with clickbait headlines. The feature of theirs that I use the most though is their blind spot feed cuz I also find it really interesting to see like which stories have had little to no reporting on either side of the political spectrum. That way I can get a really well-rounded picture of what's going on in the world right now. I've heard from so many of you that you're loving Ground News as well, which is why I'm so excited they're continuing to sponsor this channel. So, if you head to the link in the video description down below, ground. news/drbecky, or you can scan the QR code on the screen, you'll save 40% on their Vantage plan and get unlimited access to all their features. It comes out at around about $5 a month, and it's those subscription fees that help keep Ground News adree, so free of any of the bias that comes with paid advertising as well. So, big thanks to Ground News for sponsoring this video. And now let's

dive into all of this and chat about why it's so hard to find planets around our nearest stars. So there are three main ways that we find planets. First, the transit method, where the planet blocks a little bit of the star light as it passes in front of its star from our perspective, and we can record those repeated dips to know it's there. The second way is through the radial velocity method or what I call the wobble method where the planet's gravity pulls on the star so much so that the star wobbles around and we can record that wobble. And then the third main way that we detect exoplanets is through a direct image of them. So we block out the very bright light from the star and then take an image of the much fainter light reflecting off the planet. Now, in each of those cases, the planet is much easier to detect the bigger it is because then it blocks more starlight if it transits in front of its star. It would cause a bigger wobble to the star and it would reflect more light in a direct image. They're also easier to spot if they're closer in towards their star as well because then again, they block more starlight and also do that more regularly. So, we can see repeat dips in the starlight. Plus, then they also cause a bigger wobble. However, it is harder to detect in a direct image because then it starts to blend with the starlight. And they're also easier to spot around fainter and smaller stars as well. Again, because the planet causes a bigger relative drop in the light during a transit, a bigger wobble, and there's less light to block to take an image. So, we know that our methods for finding and detecting exoplanets are biased. And I talked a lot about this in my video from last week if you want to check that out. We know that we're more likely to find bigger planets orbiting close in around smaller stars. So it's unsurprising then that so far we've found two maybe three planets around the smallest star in the Alpha Centuri system, Proxima Centuri. It's a red dwarf star. So that means it's around about 15% of the size of the sun. And for context, Jupiter is 10% of the size of the sun. So any planets around Proxima Centuri are going to cause a noticeable wobble to that star. This is because the mass of the planet and the star are more closely matched. Meaning the center of mass that the two orbit around is not close to the middle of the star anymore. So all of the claimed planets around Proxima Centuri have been discovered this way. The two confirmed planets B and D are both Earthlike with very similar sizes. And then that candidate planet C, the contested one, is thought to be more of a mini Neptune in size. As for the two sunlike stars, Alpha Centuri A and B, there have been extensive monitoring campaigns over the past couple of decades. So, both transiting exoplanets and also for whether there's any wobble. And those campaigns haven't found anything, but they have put limits on any possible planets that could be there. They've essentially been able to say, okay, there's definitely not any Jupiterized planets orbiting within two times the Earth's sun distance, otherwise we would have found them already. But that still leaves the possibility of an Earthlike planet in orbit around either Alpha Centuri A or Alpha Centuri B. Because if it was there, it wouldn't cause a big enough wobble for us to be able to detect with our current generation of telescopes. So if there was no joy with the wobble method, what about with the transit method then? Well, the first issue is alignment. Because the probability that this planet system is also aligned with our solar system so much that we'd actually see the planets pass in front of their star is very low. It's much more likely that they're angled to us, maybe even being face on. But even if it wasn't, the brightness of these two stars is the real issue here. Alpha Centuri A and B blur together to be the third brightest star in the night sky. They're visible from the southern hemisphere if you want to try and spot them yourself. So detecting the tiny blip in that brightness caused by a planet, especially a smaller Earthlike planet, it's just very difficult. It gets lost in the noise. This happens even if you've just got one star that's probably varying in brightness and then the noise of your telescopes as well. But if you have a second very bright star nearby, that's all going to add more noise to the system, which is also what makes taking a direct image of any planet system for these two stars very difficult as well. Because you don't just have to block the light from one star, but both stars and cope with the light bleed from both of those stars across the rest of the image and then somehow detect a planet that is a million or so times fainter than the two star lights that you've just blocked. So

to do this, you need to use a telescope that has been designed to detect the faintest possible objects, but also one that you can point at one of the brightest objects in the night sky and not completely overwhelm your incredibly sensitive detectors, which is very risky if something goes wrong. But that is what Bman and Sangian collaborators have managed to do with JWST and Alpha Centuri A and B. Which brings me to part two, the discovery of this candidate planet with JWST. So using the mirror instrument on board JUST, Bikman and Sangian collaborators managed to get an image of these two stars with the majority of their light blocked leaving behind the classic eightointed star spike shape caused when the light changes direction as it reflects and refracts moving through the different components of the telescope. We understand that shape very well. We understand why it's a different shape for different shaped telescopes as well. I've made a video on that before if you want to check that out. And so what Bman and Sangian collaborators did was essentially take an image of another star, use that eight-ointed star shape to model for it and subtract it off the direct image of the Alpha Centuri system that they took in order to just try and remove as much starlight as they possibly could from the image. They estimated that they managed to remove about 99% of the starlight from these two incredibly bright stars. So this is what was then left over. You can see they did this for three different observations. one from August 2024, one from February 2025, and one from April 2025. And you can see that they detected a few known background stars, but also this source near to Alpha Centuri A that they've labeled as S1, which if they assume is a planet would be around about two times the distance that the Earth is from the Sun. And from the brightness, so the amount of light that it's reflecting suggests it could be a planet with the mass of Saturn, but it's around about the size of Jupiter. But it is not

actually a confirmed planet just yet. It is still a candidate, which brings me to part three, the reason why it's not actually a confirmed discovery yet. So if you look again at this image, you can see that you see this source S1 in the August 2024 image, but not in the February 2025 and April 2025 images. Repeat observations is how we know that what we've detected is actually a planet. We take lots of images over a long period of time so that we can see that planet move in its orbit, playing them back to back so that we end up with like a little exoplanet time lapse. And from that we can even work out the planet's orbit as well. But here around Alpha Centauri A, there was only one detection back in August. Now that doesn't rule it out as not being a planet, but it did make a lot more work for Bikman and Sangi and collaborators cuz they then had to confirm, okay, let's make sure that this isn't a background star or it isn't a foreground object that's photobombed the image like an asteroid in our own solar system and let's make sure that it's not just like dust in orbit around this star either. What's really interesting though is that back in 2019, the Very Large Telescope in Chile may also have observed this candidate planet as well. Those observations put the estimate at somewhere between Neptune and Saturn's mass for this candidate planet, but it was spotted at only 10% of the Earth's sun distance from the star Alpha Centuri A. Now, you might be thinking, well, that's weird cuz the candidate that JST spotted is like two times the Earth's sun distance away. But if you remember, it's very unlikely that we're seeing it directly face on. It's probably more likely that this system is at an angle. And so that even if planets don't pass in front of their stars so that we see a transit, they might pass behind the star from our perspective. And that could explain why it wasn't spotted in the February and April 2025 images. Bikman and Sangian collaborators calculated there's a 52% chance that that's what happened here. And the best fit to both the VT and JWST data would then put the planet's orbit taking around about 2 to 3 years. If that's the case, then we can estimate when we should be able to see it again, which means, you guessed it, more JST time is needed in around about August 2026 just to see if this thing reappears and we can confirm if the planet is there. But there's also a few new telescopes coming online soon that should be able to help with this. So NASA's Nancy Grace Roman Space Telescope, aka Hubble's Successor, is set to launch in late 2026 as well. I've made a whole video on that telescope before if you want to check it out. But it has an instrument on board that's specifically been designed to block out the light from two stars in an image to be able to see if there's any planets orbiting around them. is there are a lot of binary systems in the galaxy and that's one big unknown is how common are planets around binary stars. The Alvisenator system would be a perfect use case for that instrument. So I'm very excited to see what that finds. Plus, there's also an instrument on the upcoming extremely large telescope being built in Chile, which should have the sensitivity to be able to detect the wobble that this planet causes on its star if there is actually a planet there. First flight on the ELT isn't scheduled until 2029, so we've got a little bit longer to wait for that one. Then speaking of long waits, there's also NASA's Habitable Worlds Observatory that is being specifically designed to take direct images of Earthlike, possibly habitable planets, but that's not due to launch until the 2040s. So, while this is a promising candidate planet for now, there are also lots of exciting possibilities coming up to try and confirm whether this planet is actually there or not and maybe even reveal if there are any Earthlike planets in orbit around our closest sunlike stars.

Oh, this is take two. I just filmed that whole video and because I had a break for lunch in between this one and the one I filmed before and I turned my microphone off and I didn't turn it back on again. So now I've got to film the whole thing again and I'm fine. Woe is me. I think that was thunder and yet I can only see a clear blue sky out there. But yeah, that's definite thunder. Oh yeah, there comes the cloud. It's still wispy, but it's obviously there. There is the thunder and there's the rain starting. Okay. Well, space ASMR now for you. Repeat observations. Oh my gosh, the rain is getting really heavy right now. I hope you enjoyed this latest episode of Space Rain ASMR cuz apparently August has been the month for that. Oh, wait. This is posting in September, but it's the end of August right now, so