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  • [♩INTRO]

  • Back in July 2016, NASA's Juno spacecraft entered orbit around Jupiter.

  • New missions are always exciting,

  • but this one was especially cool because

  • Juno had a different orbit than previous missions to Jupiter.

  • The spacecraft is looping around the planet's poles,

  • getting as close as 3500 kilometers above the cloud tops

  • which is really close when you consider how big Jupiter is.

  • The mission will keep going for at least another few months,

  • but scientists are already picking apart the data from those super close flybys.

  • They're studying places we haven't had access to to until now,

  • including Jupiter's interior.

  • And a group of papers published this week in the journal Nature

  • are sharing some of those key findings.

  • As a gas giant, Jupiter is mostly made out of fluids.

  • It also rotates pretty quickly, experiencing only 10-hour days.

  • Because of all that,

  • astronomers expected Jupiter's mass to be distributed pretty uniformly.

  • But that's not the case.

  • These recent findings from Juno showed us

  • that its mass distribution actually varies depending on the latitude.

  • It's caused by streams of fluid,

  • both in Jupiter's atmosphere and in its interior,

  • up to 3000 kilometers below the cloud level.

  • We also learned that, below that depth, fluid just doesn't flow the same way.

  • Instead, a mix of hydrogen and helium rotates together,

  • almost like a solid body.

  • Of course, because of all the clouds,

  • we can't actually look into Jupiter's interior.

  • That would just be too easy.

  • Instead, scientists used Juno to measure how Jupiter's gravitational pull

  • changes as the spacecraft performs its flyby.

  • As Juno moves around Jupiter, it gets closer to different parts of the planet.

  • Those different parts have different amounts of mass,

  • which means gravity there will be a little stronger or weaker.

  • That will either cause Juno to speed up or slow down.

  • Then, scientists can then measure those changes in speed

  • to tell how Jupiter's mass is distributed.

  • This new Juno data is two orders of magnitude more accurate

  • than previous scans, and it'll help us better model what's happening

  • in Jupiter and in other fluid giants.

  • And there were even more findings, too.

  • One additional paper reported on the discovery of multiple cyclones

  • in both the north and south polar regions.

  • Using the infrared JIRAM and optical JunoCam,

  • Juno snapped photos of 15 separate storms,

  • observing them over seven months.

  • There were eight storms rotating around one storm in the north,

  • and five rotating around a storm in the south.

  • They all range between 4000 and 7000 kilometers in diameter,

  • and both sets of storms are arranged like polygons, which is cool.

  • Of course, it's still a mystery how they originally formed

  • and how they didn't manage to merge together

  • over the months they were observed.

  • It just means that there are still a lot more questions

  • astronomers need answers to.

  • And thankfully, Juno is sure to provide many more answers.

  • In other planetary news,

  • astronomers published a paper in The Astronomical Journal

  • announcing that a faraway exoplanet

  • has way more water in its atmosphere than we thought.

  • To figure it out, they had to create the most complete atmospheric profile

  • that's possible with current technology.

  • The planet is WASP-39b, which was discovered back in 2011.

  • It's about 700 light-years from Earth and orbits a star

  • with a mass similar to the Sun's, although it's older and a bit cooler.

  • 39b's mass is similar to Saturn's,

  • but that's about the only thing they have in common.

  • The most obvious difference is this planet doesn't have any rings.

  • But it's also much puffier.

  • It's actually one of the least dense planets ever discovered.

  • It's so puffy because it orbits really closely to its star

  • In fact, it only takes 4 days to complete one orbit!

  • All that intense heat fluffs up a bunch of the planet's matter.

  • 39b is also tidally locked,

  • which means only one side of the planet ever faces its star.

  • But powerful winds help move the heat around, so it's fairly evenly distributed.

  • The planet has a toasty equilibrium temperature of over 1100 Kelvin.

  • Because 39b doesn't really have any obscuring clouds in its upper atmosphere,

  • the Hubble Space Telescope could capture a good breakdown

  • of the atmosphere's composition.

  • It did that by looking at starlight.

  • Specifically, it looked at light from its host star

  • that traveled through the planet's atmosphere on its way to Earth.

  • Different molecules absorb different wavelengths of light,

  • so by looking at the wavelengths of starlight that are missing in the data,

  • astronomers can tell what kind of gases this atmosphere has,

  • and in what abundance.

  • What Hubble found was a lot of water vapor.

  • Like, three times more than we find in Saturn's atmosphere,

  • which was totally unexpected.

  • They figured they'd find some water, but nowhere near as much as they did.

  • This suggests 39b was pummeled by a lot of icy material when it was forming.

  • Still, based on what we know about planet formation,

  • that would've only been possible

  • if the planet formed much farther from its star than it is now.

  • And, like with any good paper, that only brings up more questions.

  • Welcome to science.

  • This study adds to the complex list of ways planets can develop,

  • and it suggests there are a lot of star systems with different stories than ours.

  • As we collect more data through research like this,

  • we'll just keep learning more.

  • And don't worry -- there's more to learn about 39b, too.

  • When the James Webb Space Telescope finally launches

  • which will hopefully happen next year

  • it'll be able to measure how much carbon 39b has in its atmosphere.

  • It'll also be able to see which carbon-based molecules

  • that carbon is locked up in.

  • That'll help astronomers pin down

  • where the exactly the planet should've formed relative to its star.

  • By better understanding how other star systems formed,

  • we'll be able to answer questions about our own neighborhood, too.

  • In November, we launched SciShow Finds:

  • a corner of the internet where we've collected artifacts of the universe

  • that fill us with wonder.

  • We were thrilled that you all cared about these special things

  • as much as we did, so we're doing it again.

  • If you're a citizen scientist, I picked out this PocketLab,

  • which is exactly what it sounds like,

  • a lab for your pocket

  • that helps you collect data out in the world and draw your own conclusions.

  • If you get a PocketLab, please, please let us know

  • what observations you make with it.

  • We'd love to hear about your experiments.

  • And longtime SciShow videomaker, Sarah Meismer,

  • has made this beloved lapel pin.

  • Get it?

  • Bee-loved?

  • It's a bee.

  • In a heart.

  • Don't bees deserve some more love?

  • Just like last time, we have a limited number of these special finds,

  • so we'll keep them up until we run out or find new special things

  • that foster our love for science.

  • So head to SciShowFinds.com to learn more

  • and know that when you buy something from SciShow Finds,

  • you're supporting the people who make and find these cool things

  • and supporting SciShow!

  • [♩OUTRO]

[♩INTRO]

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朱諾任務的新木星發現! (New Jupiter Discoveries from the Juno Mission!)

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    林宜悉 發佈於 2021 年 01 月 14 日
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