00:00Well, I hate to break it to you, but I'm told that our Earth might not be so special after
00:06all.
00:07Scientists say it could just be the last planet in our solar system that hasn't moved on yet.
00:12Yep, the worrying part is that it looks like planets don't stay Earth-like forever.
00:17They pass through it.
00:19Atmosphere, liquid water, internal heat, magnetic shields,
00:23all that lines up for a while and then, slowly, it unravels.
00:27Now, for a long time, scientists treated Earth-like planets as cosmic unicorns,
00:32one-in-a-hundred star kind of rare.
00:35But when they ran updated models with better physics and geology,
00:39researchers realized that if the conditions line up,
00:43Earth-like planets with liquid water could exist around almost every star,
00:47not one-in-a-hundred, potentially one per star.
00:51That's a hundred times more common than they thought.
00:54Our Milky Way alone has at least 100 billion stars.
00:58Hey, suddenly the universe doesn't feel empty at all,
01:01and planets don't even need oceans splashing on the surface to count.
01:05Many worlds that look frozen on the outside could be hiding liquid water deep below their crusts,
01:11quietly warm and stable.
01:13It's already happening in our own backyard.
01:16Moons like Europa and Ganymede around Jupiter,
01:19and Enceladus around Saturn look like icy balls from space.
01:23But underneath their cracked shells, there are global saltwater oceans.
01:28Even dwarf planets like Pluto and Ceres show signs of buried water.
01:32The secret sauce is heat.
01:35Radioactive elements inside a planet slowly release energy,
01:39like a tiny heater that never shuts off.
01:41Plus, gravity from nearby giant planets stretches and squeezes these worlds
01:46and creates friction heat.
01:48So, it seems pretty easy for Earth-like planets to form.
01:52And if you look at modern planet formation models,
01:55you'll see rocky planets like ours pop up all the time.
01:58It's possible that the early solar system didn't just make one Earth.
02:02It made several attempts.
02:04Mercury, Venus, Earth, and Mars all form from the same neighborhood,
02:08same materials, same chaos.
02:10Exploding stars nearby called supernovae sprayed heavy elements like iron and nickel
02:16into the cloud that became our planets.
02:18That gave them solid cores, internal heat, and the potential for magnetic fields.
02:24That's the starter kit for an Earth-like world.
02:27So, instead of Earth being a miracle,
02:29it starts to look like the survivor of a group project where everyone else dropped out.
02:36Now, Mars is the first planet in this dropout group that has been actively giving away clues
02:41that it wasn't always the dry, rusty place we see today.
02:46Scientists have spotted river deltas, minerals that only form in water,
02:50and landscapes that look carved rather than blasted.
02:53All signs point to the same thing.
02:55Mars used to be wet.
02:58The big question was never if there was water, but what kind of world it created.
03:02Was Mars frozen with bursts of melting ice, or was it warm enough to hold long-lasting oceans?
03:09New evidence tips the scale towards something huge.
03:13Around 3 billion years ago, Mars likely had a massive ocean covering most of its northern hemisphere.
03:19It was not a patchwork of lakes, but one connected body of water.
03:23That idea comes from studying the biggest canyon system in the solar system.
03:27It stretches about 2,500 miles long and up to 120 miles wide,
03:33dwarfing Earth's Grand Canyon by comparison.
03:36There is an area inside the canyon where signs point to a deep ancient lake.
03:42Scientists found special layered deposits along the canyon walls
03:45that show rivers once flowed into the canyon.
03:49Even stranger, all these deposits sit at almost exactly the same height.
03:54That tells us the water level stayed stable for a long time,
03:58and depths reached nearly 3,300 feet in some places.
04:02The canyon floor sits higher than Mars' northern lowlands.
04:06If water filled the canyon that deeply, it had to spill outward,
04:10flooding the entire northern half of the planet.
04:13In other words, Mars wasn't just wet, it was blue.
04:17This discovery comes with a warning.
04:19Mars shows how precious water really is, and how easily a planet can lose it.
04:25It looks like Mars didn't fail because it was weird or flawed.
04:30Studies now show its core stayed hot and solid for a long time.
04:35Very Earth-like in structure.
04:37The difference is in size.
04:39Mars is smaller, so it cooled faster.
04:42Once the core slowed, the magnetic field weakened.
04:45Once the field weakened, the atmosphere started leaking into space.
04:50It's like trying to hold water in a bucket full of tiny holes.
04:53Eventually, gravity loses the fight.
04:56Alright, and what about Venus and its potential for life?
05:00It has always looked like Earth's evil twin.
05:03Poisonous air, crushing pressure, surface hot enough to melt lead.
05:07But NASA's Magellan mission back in the early 1990s
05:11collected some data that tells a completely different story.
05:14One where Venus might still be alive on the inside.
05:18Magellan arrived at Venus and did something no spacecraft had done before.
05:23It mapped the entire planet's surface and gravity field in detail.
05:27At the time, scientists mostly used the images to catalog craters and strange landforms.
05:33But now, with better models and computing power,
05:36researchers are re-reading that data and realizing
05:40Venus may be far more geologically active than anyone assumed.
05:45The biggest clue comes from massive features called coronae.
05:49These are large, almost circular formations that can stretch dozens to hundreds of miles across.
05:54It's like a giant blister in the planet's crust.
05:57Venus doesn't have moving tectonic plates like Earth,
06:01but that doesn't mean nothing moves.
06:04Hot, buoyant material from deep inside the planet, the mantle,
06:07can push upward, warping and cracking the surface from below.
06:11When they combined Magellan's gravity data with its topography maps,
06:16scientists managed to peak beneath Venus's crust.
06:19They noticed hidden mantle plumes, rising columns of hot rock,
06:23that don't always show up in surface images alone.
06:26Around some coronae, researchers even found signs of subduction,
06:31where one section of crust sinks beneath another.
06:34Plus, something called lithospheric dripping,
06:37where dense surface material slowly sinks back into the mantle like cooling wax.
06:43Now, all this sounds cool,
06:45but it starts feeling way more personal when you find out Earth may have looked like this once.
06:51Coronae don't exist on modern Earth,
06:53but they might have formed billions of years ago,
06:55before plate tectonics fully took over.
06:58Studying Venus today could be like looking at a snapshot of Earth's deep past.
07:03And this is just a warm-up.
07:05NASA's Veritas mission will return to Venus with modern radar,
07:09build 3D global maps,
07:11analyze surface chemistry,
07:13and measure the planet's gravity field in far greater detail,
07:16up to four times sharper than Magellan.
07:19If Venus is still shifting, dripping, and churning inside,
07:23Veritas will catch it in the act.
07:26Now, Venus isn't the only planet getting a second look,
07:29thanks to dusty old data files.
07:31Back in 1986,
07:33Voyager 2 flew past Uranus
07:35and sent back a snapshot that confused everyone.
07:39Uranus looked like a cold, tilted, icy giant,
07:42wrapped in one of the strangest magnetic bubbles ever seen.
07:46Its magnetosphere,
07:47the invisible magnetic shield around the planet,
07:50made no sense.
07:51It was tilted by about 59 degrees,
07:54shoved off-center inside the planet,
07:57and paired with a planet already lying on its side
07:59at a 98-degree tilt.
08:02Even weirder,
08:03Voyager 2 found that Uranus' magnetosphere
08:06was almost empty.
08:07Very little plasma hung around inside it.
08:10Instead, scientists saw dense belts of high-energy electrons,
08:15packed way tighter than expected.
08:17For decades,
08:18researchers assumed this was just how Uranus worked,
08:21a permanently broken magnetic system.
08:24But now,
08:25they reanalyze Voyager 2's data with modern tools
08:28and decades of new knowledge about space weather.
08:30And it looks like Voyager 2 didn't catch Uranus
08:34in its normal state at all.
08:36It caught it when a solar storm was passing Uranus.
08:39So, Uranus might not be permanently weird.
08:42And since our entire understanding of Uranus
08:45is based on a single flyby during a cosmic storm,
08:48it could be hiding plenty of secrets.
08:51Put all this together,
08:52and the solar system starts to look less like a tidy family
08:55and more like a graveyard of transformed former Earths.
08:59And when scientists say Earth isn't a planet type,
09:02but a phase,
09:03they're not just being dramatic.
09:05Earth just happens to be the last one in the solar system
09:08still holding the line.
09:13That's it for today.
09:14So hey, if you pacified your curiosity,
09:17then give the video a like and share it with your friends.
09:19Or if you want more,
09:20just click on these videos and stay on the bright side!
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