Merle Schrader has been speaking with Chris Smith…Merle - We know on Earth vaguely what drives the weather.
So what we've found is what drives weather on planets outside of our own solar system that aren't as resolved as our solar system planets.
Merle - Outside of our solar system but well within our galaxy.
So we use them as laboratories to study weather on these worlds outside of our solar system and understand what drives the weather and what shapes their atmospheres.
Chris - How do you know that's actually the weather, in inverted commas, that you're seeing?
Scientists say they can now track weather patterns found on far-away planets, starting with a nearby brown dwarf; this is basically a massive body not quite big enough to have become a star and located 20 light years away from Earth. Being relatively close, and a source of heat makes it a convenient study subject. The team at Trinity College Dublin have been able to watch the patterns of thermal radiation coming from the object change as it rotates, and map those onto models of how we think atmospheres, clouds and storms work in general. It’s a step towards being able to read the weather on remote worlds, helping us to home in, eventually, on the ones that might be habitable. Merle Schrader has been speaking with Chris Smith…
Merle - We know on Earth vaguely what drives the weather. So what we've found is what drives weather on planets outside of our own solar system that aren't as resolved as our solar system planets. So we can't take pictures, so we have to come up with new tools to kind of disentangle the weather and that's what we're presenting here.
Chris - And where are you looking at specifically?
Merle - Outside of our solar system but well within our galaxy. So what we call brown dwarfs are worlds that formed like stars but they don't shine like stars because they're not massive enough. So they cool down throughout their lifetimes and they develop atmospheres very similar to planets that we have in our solar system and they're easier to study than exoplanets because they're not hidden beside these bright stars because planets form around stars but these brown dwarfs don't. So we use them as laboratories to study weather on these worlds outside of our solar system and understand what drives the weather and what shapes their atmospheres.
Chris - How are you looking at them? How do you spot them?
Merle - We use the James Webb Space Telescope and we look at them in the infrared range. So we essentially observe the heat that is emitted from these objects and as they rotate in the sky we see the different sides of the object and we figured out a few years ago that as they rotate the amount of light and the colour that we see changes and that's because the different sides of the objects have different cloud phenomena, different temperatures, different storms going on. So we can see this change in light and we can try and relate it back to the weather on these objects.
Chris - How do you know that's actually the weather, in inverted commas, that you're seeing? That those changes in light and dark and therefore the density of what's around the object, how do you know that's the weather and clouds and so on?
Merle - So like I mentioned, brown dwarfs form like stars so they create all of this mass and then that leaves them kind of in this hot state where they emit energy and this energy is emitted in the form of heat and then as this light or heat reaches the James Webb Space Telescope certain colours of the light are missing or are brighter and that's because it has to pass whatever is between where it is emitted in the centre of these objects all the way to us. And what it passes through is clouds and storms and all of these things that happen inside an atmosphere but what we actually observe is one pixel spread across colour space. So we call that a spectrum where we have the redder colours and the bluer colours and depending on what's happening in the atmosphere we see more of the red or more of the blue and we can relate that back to the weather and the reason that we know that there are likely clouds and storms and changes in chemistry is because we can set up experiments in laboratories on Earth and mimic what we expect these clouds to look like and what the heat from the objects is like naturally and we can see how the light changes in our lab and compare it to what we see in space. For this specific object and the reason why we chose it is because it's relatively close to us and by relatively close I mean it's so far away that it took the light from the object when it was emitted 20 years to reach Earth. So the light was emitted back when I was born.
Chris - [laughs] It's an interesting way of looking at it indeed. What can we learn from doing this though? Because you're looking at a dot in the sky which is 20 light years away, why is that going to help us in our quest to understand more about how the universe works?
Merle - I mean the ultimate goal is always to try and figure out if we're alone in the universe at least for the exoplanet and brown dwarf people. I think the faraway goal is that and I don't think that the technique that I've presented here is necessarily the way to do this but what all scientists do all of the time is develop more and more tools to use what we can observe and what we can know in more efficient ways and to learn more from the data that we have and are able to get. And so these tools that we're developing are really setting out to understand these atmospheres to an extent where we can understand what drives the weather, what shapes it. We know on our own Earth that part of the reason why life is stuck around for so long is because we have this atmosphere that protects us and Mars has a weaker atmosphere and Mars has lost water and we know that those are likely related facts. So in studying these atmospheres we're able to learn about the conditions on these objects which ultimately will be important when looking for habitable targets.
