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The Youngest Planet Ever Found Is Still Being Built · The Last Observer: Science and Beyond

• 0:00
  Speaker 1: Welcome to The Last Observer, a journey through science, history,
• 0:04
  Speaker 1: and the universe's greatest mysteries. From ancient enigmas to the
• 0:08
  Speaker 1: deepest questions at the frontiers of reality, we explore the discoveries, ideas,
• 0:13
  Speaker 1: and mysteries that challenge what we think we know. Stay curious,
• 0:18
  Speaker 1: keep questioning, and let's search for the truth beyond the known.
• 0:27
  Speaker 2: Welcome to The Last Observer Podcast. Today, we will talk
• 0:31
  Speaker 2: about the youngest planet ever confirmed, a world still being
• 0:35
  Speaker 2: built while we watch.
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  Speaker 3: A planet younger than a million years. That number barely
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  Speaker 3: makes sense.
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  Speaker 2: Earth is four and a half billion years old. This
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  Speaker 2: object is a newborn by comparison.
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  Speaker 3: Astronomers named it Elias 224b. It sits about 450 light
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  Speaker 3: years away.
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  Speaker 2: And it is still sitting in the dusty disk that
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  Speaker 2: made it, still gathering gas.
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  Speaker 3: That is the part that got me. We are not
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  Speaker 3: looking at a finished world. We are looking at construction.
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  Speaker 2: The confirmation came from archival images at the Keck Observatory
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  Speaker 2: in Hawaii.
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  Speaker 3: They were not even taking brand new pictures of this
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  Speaker 3: star first. They went digging in old files.
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  Speaker 2: A team led by Andrea Bernardi at Universidad Diego Portales
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  Speaker 2: pulled those frames and locked the companion in place.
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  Speaker 3: The paper landed in the Astrophysical Journal letters. NASA highlighted
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  Speaker 3: it on September 16th.
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  Speaker 2: Previous record holders were around 5 million years old. Worlds
• 1:34
  Speaker 2: around PDS-70 and WISPIT-2.
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  Speaker 3: 5 million already felt young. This one slashes that age
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  Speaker 3: by a factor of 5 or more.
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  Speaker 2: The host star itself may be only 400,000 years old
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  Speaker 2: on some estimates.
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  Speaker 3: Dating baby stars is messy, but every clock they use
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  Speaker 3: still says this system is extremely young.
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  Speaker 2: The planet is roughly Jupiter's mass. Estimates run from about
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  Speaker 2: two to four Jupiters if you ignore extra glow from accretion.
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  Speaker 3: It orbits 55 astronomical units from its star, 55 times
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  Speaker 3: farther than Earth sits from the Sun.
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  Speaker 2: That is out past Neptune if you drop this system
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  Speaker 2: on top of ours.
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  Speaker 3: And that is the problem. Standard core accretion is supposed
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  Speaker 3: to be slow out there.
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  Speaker 2: Textbooks said a Jupiter at Jupiter's distance needs a few
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  Speaker 2: million years. Farther out should take even longer.
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  Speaker 3: This thing formed in under a million years at 55 AU.
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  Speaker 3: The models are missing a shortcut.
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  Speaker 2: Lucas Chiesa, a co-author, put it plainly. Even our best
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  Speaker 2: formation models are still missing important processes.
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  Speaker 3: The disk around Elias 224 already had a narrow gap.
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  Speaker 3: The planet sits right in that gap.
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  Speaker 2: That is the smoking gun people wanted. Gaps in baby
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  Speaker 2: disks really can be carved by planets, not just by
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  Speaker 2: other physics.
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  Speaker 3: ALMA has shown those gaps appearing while stars are still
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  Speaker 3: embedded in their birth clouds.
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  Speaker 2: Now there is a point source in one of those
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  Speaker 2: gaps with the right motion to be bound to the star.
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  Speaker 3: They checked proper motion between 2018 and 2020. It did
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  Speaker 3: not drift like a background star.
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  Speaker 2: It moved with the host. That is how you know
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  Speaker 2: it is not a coincidence in the field.
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  Speaker 3: Keck's vortex coronagraph blocked the starlight so the faint companion
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  Speaker 3: could show up.
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  Speaker 2: The object is at the edge of what current adaptive
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  Speaker 2: optics can catch. Next telescopes will make this easier.
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  Speaker 3: Roman Space Telescope is going to open this hunt wide.
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  Speaker 3: A field a hundred times Hubble's with sharp detail.
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  Speaker 2: Imagine finding a whole nursery of worlds this young. Not
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  Speaker 2: one oddball.
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  Speaker 3: That would tell us giant planets are common almost as
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  Speaker 3: soon as disks exist.
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  Speaker 2: Core accretion still looks like the winner here. The disk
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  Speaker 2: shape matches that picture better than a fragmenting spiral.
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  Speaker 3: Gravitational instability would leave different fingerprints, big spiral arms tearing
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  Speaker 3: themselves apart.
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  Speaker 2: Surveys keep finding gaps and rings far more often than
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  Speaker 2: those fragmenting arms.
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  Speaker 3: So the quiet, pebble-by-pebble route can run faster than we thought.
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  Speaker 2: Pebbles drift inward. They pile up at pressure bumps. A
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  Speaker 2: core grows. Then gas floods on.
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  Speaker 3: If the disk is massive and the bump is strong,
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  Speaker 3: that last gulp of gas can be quick.
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  Speaker 2: The planet is still accreting. It is still bright from
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  Speaker 2: that incoming material.
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  Speaker 3: That extra light makes mass estimates tricky. You can overcount
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  Speaker 3: if you treat it like a finished, cooling world.
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  Speaker 2: They flagged that. The 2 to 4 Jupiter range ignores
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  Speaker 2: accretion glow on purpose.
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  Speaker 3: Independent mass from how the disk gas moves would help.
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  Speaker 3: Future spectrographs can do that.
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  Speaker 2: I keep coming back to the tying scale. One million
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  Speaker 2: years is nothing in geology.
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  Speaker 3: Dinosaurs lasted more than 150 million. This planet formed in
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  Speaker 3: a blink after its star lit up.
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  Speaker 2: If Earth history were one year, this world would be
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  Speaker 2: younger than the first morning of January 1st.
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  Speaker 3: That image stuck with me. We are watching the first
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  Speaker 3: hours of a planet's life.
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  Speaker 2: And it is already a giant, not a Mars-sized seed
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  Speaker 2: waiting around.
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  Speaker 3: That changes how we think about the solar system, too.
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  Speaker 3: Jupiter may have assembled earlier than some models allowed.
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  Speaker 2: If giants form fast and far out, they can sculpt
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  Speaker 2: the leftover disk before the inner planets finish.
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  Speaker 3: That is one idea for why we have no super-Earths
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  Speaker 3: packed close to the Sun.
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  Speaker 2: A early Jupiter can starve or scatter the inner building blocks.
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  Speaker 3: This discovery does not prove that story. It just makes
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  Speaker 3: a fast outer giant less exotic.
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  Speaker 2: The star is an orange dwarf, still wrapped in its
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  Speaker 2: natal material.
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  Speaker 3: 450 light years is close enough that we can keep
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  Speaker 3: watching the disk evolve.
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  Speaker 2: Years from now, the gap may widen. The planet may
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  Speaker 2: dim as accretion slows.
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  Speaker 3: That would be a time lapse of planet finishing. We
• 6:02
  Speaker 3: almost never get that.
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  Speaker 2: Most exoplanets we know are old. Billions of years, quiet
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  Speaker 2: and settled.
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  Speaker 3: This one is messy, dusty, still eating. That mess is
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  Speaker 3: the science.
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  Speaker 2: There is a caution. Age estimates for objects under a
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  Speaker 2: million years have large error bars.
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  Speaker 3: Different papers on this same star quote 400,000 years and
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  Speaker 3: up to about a million.
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  Speaker 2: Even at the old end of that range, it still
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  Speaker 2: beats the previous record by a wide margin.
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  Speaker 3: So the headline survives the uncertainty. The exact birthday does
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  Speaker 3: not have to be perfect.
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  Speaker 2: Another caution is mass. Disk contamination and accretion light both
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  Speaker 2: blur the number.
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  Speaker 3: If it were a brown dwarf, the story would change.
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  Speaker 3: The photometry still lands in the planet range.
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  Speaker 2: The gap properties also match a few Jupiter body. Two
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  Speaker 2: independent hints point the same way.
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  Speaker 3: I like that they used archives. Science sitting on disk,
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  Speaker 3: waiting for someone to notice.
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  Speaker 2: A lot of astronomy now is like that. The telescope
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  Speaker 2: already looked. The insight comes later.
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  Speaker 3: It also means smaller teams can make discoveries without booking
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  Speaker 3: new nights immediately.
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  Speaker 2: What would surprise you more, finding this was a fluke
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  Speaker 2: or finding a dozen more next year?
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  Speaker 3: A dozen more. Because then fast outer giants are the rule,
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  Speaker 3: not a headline.
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  Speaker 2: And then every protoplanetary disk with a gap becomes a
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  Speaker 2: suspect list.
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  Speaker 3: ALMA maps the dust. Extreme adaptive optics hunts the point
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  Speaker 3: source inside.
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  Speaker 2: That pipeline is already running. This confirmation is the proof
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  Speaker 2: of concept people needed.
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  Speaker 3: There is a quiet human piece, too. a doctoral student
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  Speaker 3: leading the lock on the youngest world we know.
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  Speaker 2: Chilean institutions plus Keck plus NASA archives. A wide net.
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  Speaker 3: When I first read Jupiter mass at 55 AU in
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  Speaker 3: under a million years, I thought the sentence was wrong.
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  Speaker 2: Same. It sounds like a contradiction until you remember disks
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  Speaker 2: can be dense and brief.
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  Speaker 3: Dense enough that pebbles do not have to wander for ages.
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  Speaker 3: They stall and pile.
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  Speaker 2: Pressure bumps act like traffic jams. Material stacks. Cores appear sooner.
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  Speaker 3: Then, runaway gas accretion can finish the giant while the
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  Speaker 3: disk is still thick.
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  Speaker 2: If the disk drains in two or three million years,
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  Speaker 2: you need that speed or you never get a Jupiter.
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  Speaker 3: This object says the race can be won early, at
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  Speaker 3: least once.
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  Speaker 2: I keep picturing that heart-shaped glacier on Pluto from other
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  Speaker 2: news this week. Then this baby giant.
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  Speaker 3: Different stories, same feeling. The outer solar system and other
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  Speaker 3: systems stay restless.
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  Speaker 2: Worlds do not freeze into museum pieces as fast as
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  Speaker 2: we assumed.
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  Speaker 3: Elias 224b will not stay this bright forever. Catch it
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  Speaker 3: while the disk still feeds it.
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  Speaker 2: That is a good reason for follow-up this decade, not
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  Speaker 2: in 20 years.
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  Speaker 3: Spectra of the accretion flow. Maps of the gap edges.
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  Speaker 3: A second epoch of motion.
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  Speaker 2: If a smaller inner companion exists, next-generation optics might pull
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  Speaker 2: it out.
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  Speaker 3: The paper already notes that closer, smaller worlds would need
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  Speaker 3: those future instruments.
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  Speaker 2: So this is both a result and an invitation.
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  Speaker 3: The surprising part is not just youth. It is youth
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  Speaker 3: plus distance plus mass all at once.
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  Speaker 2: Any one of those we could swallow. Together they stretch
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  Speaker 2: the theory.
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  Speaker 3: Theories should stretch. That is how they get better.
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  Speaker 2: I am still stuck on the idea that a planet
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  Speaker 2: can be younger than human civilization by a huge factor
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  Speaker 2: and already be a giant.
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  Speaker 3: Civilization is 10,000 years. This world is up to a million.
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  Speaker 3: Still a baby on cosmic clocks.
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  Speaker 2: Yes, the comparison that matters is to other planets, not
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  Speaker 2: to us.
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  Speaker 3: Against other planets, it is the infant in the room.
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  Speaker 2: And we found it by looking again at pictures that
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  Speaker 2: already existed.
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  Speaker 3: That is the kind of science that rewards patience and
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  Speaker 3: curiosity more than spectacle.
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  Speaker 2: No new explosion, no dramatic collision captured live, just a
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  Speaker 2: faint speck that refused to be background.
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  Speaker 3: A speck sitting in a gap, still growing. rewriting the
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  Speaker 3: clock on how giants are born.
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  Speaker 2: That is enough wonder for one night.
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  Speaker 3: The disk is still there. The planet is still feeding.
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  Speaker 3: The models have homework.
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  Speaker 2: We will keep watching the sky for the next infant world.
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  Speaker 2: There will be more.
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  Speaker 3: When the next one appears, we will already know the
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  Speaker 3: question to ask. How did you grow so fast, so
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  Speaker 3: far from home?
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  Speaker 2: Until then, remember this name, Elias 224b, a planet still
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  Speaker 2: becoming a planet.
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  Speaker 3: Thanks for listening to the Last Observer podcast.
• 10:51
  Speaker 2: Go look up. Some of those quiet stars are still
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  Speaker 2: building worlds.
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  Speaker 3: There is another layer I have not shaken yet. How
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  Speaker 3: a gap that narrow can host a full giant so early.
• 11:02
  Speaker 2: The gap is not a canyon the size of a
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  Speaker 2: solar system. It is a thin, dark lane in a
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  Speaker 2: bright ring.
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  Speaker 3: And the planet sits inside that lane like a marble
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  Speaker 3: in a groove.
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  Speaker 2: Theory said you need time for a core to reach
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  Speaker 2: the critical mass before gas collapses onto it.
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  Speaker 3: 10 Earth masses is the usual trigger. Then the envelope
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  Speaker 3: floods in.
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  Speaker 2: Building 10 Earths of rock and ice at 55 AU
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  Speaker 2: sounded slow because solids are sparse out there.
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  Speaker 3: Unless the solids are not sparse. Unless a trap concentrates them.
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  Speaker 2: That is the pebble trap idea. Drift, stall, pile, grow.
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  Speaker 3: Once the core is heavy enough, the gas does not
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  Speaker 3: care how far you are from the star. It just falls.
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  Speaker 2: Distance still matters for temperature and ice lines, but the
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  Speaker 2: clock can compress.
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  Speaker 3: I keep comparing this to baking bread. You think it
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  Speaker 3: needs hours, then someone uses a hotter oven.
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  Speaker 2: The disk is the oven, massive, short-lived, full of fuel.
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  Speaker 3: If most disks fade in a few million years, the
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  Speaker 3: giants we see around older stars had to finish early.
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  Speaker 2: This object is the first time we catch one still
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  Speaker 2: in the kitchen.
• 12:15
  Speaker 3: PDS 70 already showed two planets in a cavity, but
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  Speaker 3: those stars are older.
• 12:20
  Speaker 2: Wispit 2 added more, still older than this by several
• 12:24
  Speaker 2: million years.
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  Speaker 3: So the sequence now has an earlier chapter, embedded star,
• 12:30
  Speaker 3: narrow gap, giant already there.
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  Speaker 2: That sequence matters for how we read every ALMA gallery
• 12:36
  Speaker 2: of rings.
• 12:38
  Speaker 3: Those pretty dust rings are not abstract art. Some of
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  Speaker 3: them are construction sites.
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  Speaker 2: Not all of them. Magnetic fields and ice lines can
• 12:46
  Speaker 2: scope dust too.
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  Speaker 3: The difference is a point source that moves with the star.
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  Speaker 3: That is the tell.
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  Speaker 2: Keck gave them two epochs, two years apart. Enough to
• 12:56
  Speaker 2: kill the background star excuse.
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  Speaker 3: A static speck in the galaxy would have slid relative
• 13:01
  Speaker 3: to the star. This one did not.
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  Speaker 2: Simple test, huge consequence.
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  Speaker 3: I also like that they surveyed seven stars and this
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  Speaker 3: one paid off.
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  Speaker 2: Targeted hunting beats staring at random fields, when you already
• 13:15
  Speaker 2: know where gaps sit.
• 13:17
  Speaker 3: Choose the discs with the cleanest lanes, then look inside
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  Speaker 3: the lanes.
• 13:22
  Speaker 2: It sounds obvious after the fact. Most good methods do.
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  Speaker 3: What we still cannot see is the core itself, only
• 13:29
  Speaker 3: the glowing envelope and the hole it dug.
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  Speaker 2: The rock and ice seed is hidden under the gas
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  Speaker 2: it attracted.
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  Speaker 3: That is fine. We infer the seed from the hole.
• 13:38
  Speaker 2: And the Future mass from kinematics will tighten that inference.
• 13:43
  Speaker 3: Watch the gas speed up and slow down around the orbit.
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  Speaker 3: That is a scale.
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  Speaker 2: Clouds in front of the star make that measurement noisy
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  Speaker 2: right now.
• 13:52
  Speaker 3: Better instruments on bigger telescopes will cut through some of
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  Speaker 3: that noise.
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  Speaker 2: There is a philosophical itch here. We talk about planets
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  Speaker 2: as finished objects.
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  Speaker 3: This one refuses the noun. It's still a verb. It
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  Speaker 3: is still forming.
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  Speaker 2: Language lags behind the physics. We need a word for
• 14:09
  Speaker 2: a world in the act.
• 14:11
  Speaker 3: Proto-planet is close. People use it for smaller embryos too.
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  Speaker 2: Call it a growing giant and stay honest about the uncertainty.
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  Speaker 3: Honesty is the point of this whole episode. The result
• 14:23
  Speaker 3: is strong. It is not final scripture.
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  Speaker 2: Ages will be revised. Masses will shift by a factor
• 14:29
  Speaker 2: of two. The youth record may stand.
• 14:32
  Speaker 3: Even if a slightly older age wins, the formation speed
• 14:36
  Speaker 3: problem remains.
• 14:37
  Speaker 2: You still have a Jupiter-class body far from its star
• 14:41
  Speaker 2: before the disk should have time.
• 14:43
  Speaker 3: That is the scientific importance, not the record sticker on
• 14:46
  Speaker 3: the jar.
• 14:47
  Speaker 2: Records get people in the door. The missing process keeps
• 14:51
  Speaker 2: them thinking.
• 14:52
  Speaker 3: I keep wondering about moons. Can a giant this young
• 14:55
  Speaker 3: already have a disk of its own?
• 14:57
  Speaker 2: Some forming giants should. Circumplanetary disks feed both the planet
• 15:02
  Speaker 2: and future satellites.
• 15:04
  Speaker 3: We do not have that detection here yet. It would
• 15:07
  Speaker 3: be the next prize.
• 15:09
  Speaker 2: A moon system born while the planet itself is still eating.
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  Speaker 2: Nested construction.
• 15:14
  Speaker 3: Jupiter's big moons likely form that way. We missed the
• 15:18
  Speaker 3: live show in our own system.
• 15:20
  Speaker 2: Other stars let us watch the rerun if we are
• 15:22
  Speaker 2: lucky and sharp enough.
• 15:25
  Speaker 3: 450 light years is lucky. Close enough for serious follow-up.
• 15:29
  Speaker 2: Not next door. Not hopelessly far. The Goldilocks distance for
• 15:34
  Speaker 2: this kind of work.
• 15:36
  Speaker 3: I would love a simple animation in my head. Dust lane,
• 15:39
  Speaker 3: dark gap, a warm point, streams of gas.
• 15:43
  Speaker 2: Hold that image. That is what the data compress into.
• 15:46
  Speaker 3: And somewhere in that image is a clock running faster
• 15:49
  Speaker 3: than the textbooks printed.
• 15:51
  Speaker 2: Textbooks will catch up. They always do when the sky
• 15:54
  Speaker 2: refuses the old timeline.
• 15:56
  Speaker 3: Until they do, we get to sit with the surprise.
• 15:59
  Speaker 2: Surprise is the correct scientific emotion here. Not hype, not dismissal.
• 16:05
  Speaker 3: The evidence is images, motion, and a disk that already
• 16:09
  Speaker 3: knew the planet was there.
• 16:10
  Speaker 2: The disk announced the planet before we confirmed the speck.
• 16:14
  Speaker 2: That still amazes me.
• 16:16
  Speaker 3: Nature left a note. We finally read it.
• 16:19
  Speaker 2: More notes are sitting in other archives. Other gaps. Other
• 16:23
  Speaker 2: faint points.
• 16:24
  Speaker 3: Someone will open those folders this year. Maybe another record falls.
• 16:29
  Speaker 2: If it does, the story will not be that we
• 16:31
  Speaker 2: were wrong to be excited today.
• 16:34
  Speaker 3: It will be that the nursery is crowded. Giants start
• 16:37
  Speaker 3: early in many houses.
• 16:39
  Speaker 2: That would be a quieter headline and a deeper truth.
• 16:42
  Speaker 3: For tonight, the headline is one world, one gap, one
• 16:46
  Speaker 3: clock that runs hot.
• 16:48
  Speaker 2: Elias 224b is still gathering itself together while we talk.
• 16:53
  Speaker 3: By the time this episode reaches someone, a little more
• 16:56
  Speaker 3: gas will have fallen in.
• 16:58
  Speaker 2: Not enough to notice, enough to remember that planets are processes.
• 17:03
  Speaker 3: We will leave it there, a baby giant in a
• 17:06
  Speaker 3: dusty lane, rewriting how fast a world can appear.
• 17:10
  Speaker 2: Look up when you can. The construction never paused for us.
• 17:13
  Speaker 2: One last thread before we close. What this does to
• 17:17
  Speaker 2: the idea of a typical planet.
• 17:19
  Speaker 3: Typical used to mean old, isolated, and done growing.
• 17:23
  Speaker 2: Now typical might include a long, messy youth we simply
• 17:26
  Speaker 2: could not see before.
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  Speaker 3: Our own Jupiter finished that youth four and a half
• 17:31
  Speaker 3: billion years ago.
• 17:33
  Speaker 2: We inherited the quiet ending and mistook it for the
• 17:36
  Speaker 2: whole plot.
• 17:36
  Speaker 3: Other stars still run the opening act in public.
• 17:40
  Speaker 2: That is why archive work matters. The opening act was
• 17:44
  Speaker 2: already filmed.
• 17:45
  Speaker 3: We just needed someone to press play on the right frames.
• 17:49
  Speaker 2: If you teach this tomorrow, start with the gap, then
• 17:52
  Speaker 2: the motion, then the age.
• 17:54
  Speaker 3: Gap first, because the disc pointed at the crime scene.
• 17:58
  Speaker 2: Motion second, because coincidence had to die.
• 18:01
  Speaker 3: Age last. because that is the part that breaks the
• 18:04
  Speaker 3: old clock.
• 18:06
  Speaker 2: Students will ask if we might be wrong, say yes,
• 18:09
  Speaker 2: then show why the wrong answers are fewer now.
• 18:12
  Speaker 3: Background star is weaker. Brown dwarf is less likely. Empty
• 18:17
  Speaker 3: gap is gone.
• 18:18
  Speaker 2: What remains is a young giant that formed too far,
• 18:22
  Speaker 2: too soon, and is still eating.
• 18:24
  Speaker 3: That remaining story is enough. It does not need extra drama.
• 18:29
  Speaker 2: The sky provided the drama by being faster than our patience.
• 18:33
  Speaker 3: We will check back when new optics land. The lane
• 18:36
  Speaker 3: will still be there.
• 18:37
  Speaker 2: And if a fainter sibling hides closer in, that is
• 18:41
  Speaker 2: the next sentence of the same chapter.
• 18:43
  Speaker 3: A family of worlds assembling while the dust has not
• 18:46
  Speaker 3: even cleared.
• 18:47
  Speaker 2: Hold that picture. A star not yet settled. A giant
• 18:51
  Speaker 2: not yet finished. A gap like a signature.
• 18:54
  Speaker 3: That is the last observer kind of story. Quiet evidence,
• 18:58
  Speaker 3: loud implications.
• 19:00
  Speaker 2: Thanks for staying with the details all the way through.
• 19:03
  Speaker 3: The planet will keep growing after we stop talking. That
• 19:07
  Speaker 3: feels like the right ending.