0:00 In July of 2076, humanity gets a once-in-a-lifetime appointment with a visitor from the dawn of the solar system.0:08 And if we miss it, our next chance is more than eleven THOUSAND years away.0:14 Last time we talked about the bizarre dancing plague of 1518, a mystery that unfolded on a human scale.0:21 This is a story that unfolds on a scale that breaks the human mind.0:26 The visitor is a dwarf planet named Sedna.0:29 And calling its journey around the sun an "orbit" feels like an insult to the word.0:36 Earth's orbit is a tidy, nearly circular path we complete every 365 days.0:41 Predictable.0:42 Sedna’s orbit is a deranged, wildly stretched-out ellipse.0:46 At its closest, it’s still way, way beyond Pluto.0:50 At its farthest...0:51 it’s nearly a thousand times the distance from the Earth to the Sun.0:57 It takes Sedna about eleven thousand, four hundred years to make ONE trip.1:02 When it was last in this part of the solar system, humans were just starting to figure out agriculture.1:10 The pyramids hadn't been built.1:12 Rome wasn't even a rumor.1:14 It moves so slowly out there in the dark, at about three percent of Earth's orbital speed, that its discoverers almost missed it.1:24 They were looking for tiny movements against the background of fixed stars, and Sedna...1:30 barely moved.1:31 It was like trying to spot a glacier moving in real time.1:36 So why should you care about this frozen, reddish rock crawling through the abyss?1:42 Because of what its journey tells us.1:44 Michael Brown, the astronomer who co-discovered it, called Sedna a FOSSIL RECORD of the earliest solar system.1:53 Here's the thing.1:54 Most of the planets and asteroids in our neighborhood have been smashed around, cooked by the sun, and gravitationally bullied for four and a half billion years.2:06 They’re like weathered ruins.2:08 But Sedna lives so far out, in such a stable, cold, lonely orbit, that it’s almost perfectly preserved.2:16 It’s a pristine artifact from the sun’s nursery.2:20 It's like finding a perfectly preserved mosquito in amber, except the mosquito is the size of Alaska and the amber is the cold, dark void at the edge of everything we know.2:32 Its bizarre orbit suggests something threw it out there.2:37 Maybe a passing star grazed our solar system billions of years ago and flung Sedna into its strange path.2:45 Or—and this is the wild part—maybe it was nudged by a ghost.2:49 A giant, unseen planet lurking in the darkness far beyond Neptune, a hypothetical Planet Nine.2:56 Sedna’s weird path is one of the biggest pieces of evidence we have that this hidden world might actually exist.3:04 Its orbit is a clue to a mystery we haven't even solved yet.3:09 And you've seen this pattern before.3:12 The discovery of one strange outlier that forces everyone to redraw the map.3:17 When astronomers found Sedna, and other objects like it, they had to have a serious talk.3:24 It led directly to that 2006 decision by the International Astronomical Union, the one that re-defined what a "planet" is and famously reclassified Pluto.3:36 This one weird, red rock broke our model of the solar system.3:40 Which brings us back to 2076.3:42 That's when Sedna reaches perihelion—its closest point to the sun.3:47 "Closest" is relative, of course.3:50 It'll still be 76 times farther from the sun than Earth is.3:54 But for the first time in over eleven millennia, it will be within reach of a potential robotic mission.4:02 This isn't like going to Mars, where if one mission fails, we can just send another one in a couple of years.4:10 This is a one-shot deal.4:12 A singular opportunity for our generation, and dozens of generations to come.4:18 Miss this window, and Sedna swings back out into the darkness for another eleven thousand years, taking its secrets with it.4:27 It's a reminder that the universe operates on timelines that are completely indifferent to us.4:34 We’re living through the one moment, the only moment, when this ancient messenger comes close enough to say hello.4:43 It's a cosmic time capsule, floating in the dark, and the key is about to turn.
