Bizarre exoplanet clouds + Counting insects with weather radar
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What are the bizarre clouds found on WASP-94A b?
Hey, it's Flora, and you're listening to Science Friday. It seems like every week a new exoplanet drops. NASA counts 6,000 official alien worlds, with around 8,000 more suspected. They're stuck on the wait list till more research can be done to confirm them. One way to spot an exoplanet is to use a telescope to carefully look at the light of a star, watching for a tiny periodic dip in brightness as a planet crosses in front of it. But now researchers say that using this transit method, they detected not just a planet, but its clouds. And the clouds on this one gas giant, some 700 light years away, are super weird. They're made of rock. Here to tell us more is Dr. David Singh. He's a Bloomberg Distinguished Professor of Earth and Planetary Sciences at Johns Hopkins.
Hey, David.
Hello. Thank you for having me.
Thanks for being here. Tell us about this planet that you've been looking at and what the weather's like.
Well, this is a planet, what we call a hot Jupiter. It's a gas giant, much like Jupiter, but it's orbiting very close to a host star. And as a result, it's heated up to very high temperatures, up to 1,500 degrees Kelvin. And at those temperatures, what we normally experience as, say, rocks, actually can form clouds in the atmosphere.
Like they're being boiled off the surface?
Well, this is a gas giant, so there's no surface, but indeed, if you get hotter than about 1500, these rocks are actually in vaporous form. And as it gets colder, they can condense into solid, small particles.
Yeah, how should I be imagining these clouds? Are they puffy like our clouds, or are they filled with little granules?
Well, I mean, you can sort of think of them as little granules, but more like micron-sized tiny sand particles, like, say, quartz here on Earth. So, you know, we don't really know how puffy and so forth they are, but just imagining sort of a big puffy cloud made of little quartz crystals is a good way to think about them.
I mean, does that mean the atmosphere is doing something special to keep them aloft?
Yes, actually, it's a big surprise on this planet. What we find is the clouds are at very high altitudes. So well above their stratosphere, up into even the mesosphere, and actually large particles. So it was actually a big surprise to see them up there. Everyone expected... you know, something that big and heavy just to fall out. And so normally we would see the clouds at a much lower level.
How do astronomers detect clouds on exoplanets?
And so the planet must have actually very vigorous mixing, turbulent mixing to keep those sand clouds that high in the atmosphere. It's really surprising.
What would they, you know, if I could bubble up below them, I guess, what would they look like in the sky? Is it like a haze or a fog or are they, you know, like a cumulus cloud here on Earth?
It would look like a very actually thick, dense cloud. So on this particular planet, the clouds are actually even confined to the morning side of the planet. So the morning side is completely cloudy and the evening side is actually completely clear. It's much hotter and those clouds can't form. And so I kind of imagine it sort of like you're in San Francisco and in the morning it's all cloudy and you can't see anything anymore. And then by the afternoon, they've all boiled off and you can see the clear sky.
They burn off, as we say. How do you get enough resolution to be able to see the clouds? I mean, that seems amazing.
Yeah, well, we've been studying exoplanets through the transit technique for nearly 25 years, and we've been mainly using the Hubble Space Telescope during that time. But now we have the powerful JWST telescope, and that's given us actually two important advances to be able to make this measurement. The one is... Hubble is in low Earth orbit. It's orbiting around the Earth about every 90 minutes. And so it spends half of its time on the day side of our planet and half of it on the night side. Well, when we look at these transit events of these exoplanets, you know, we're looking at it over the course of several hours.
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Chapters
5 chapters
1
What are the bizarre clouds found on WASP-94A b?
0:03–2:53
2
How do astronomers detect clouds on exoplanets?
2:53–6:01
3
What makes the clouds on WASP-94A b unique?
6:01–12:45
4
How does the atmosphere on WASP-94A b support cloud formation?
12:45–20:38
5
What is the significance of the James Webb Space Telescope in exoplanet research?
20:38–21:26
Speakers
3 identifiedMore from Science Friday
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