00:00In 2017, a strange object was spotted in our Solar System.
00:06It had the shape of a long tube, similar to a pancake.
00:10No known asteroid or comet we've seen looks like that.
00:13Its exterior was also peculiar.
00:16It was at least 10 times more reflective than the average stuff that flies through space,
00:20with some saying it had a surface similar to polished metal.
00:24When it went past the Sun and left our reach, it accelerated faster than what our gravity
00:29could account for.
00:31At first glance, it was like this thing had a rocket strapped to its back.
00:35This unusual visitor even got a special name – Amuamua.
00:39It comes from Hawaiian and translates to scout or visitor from a faraway land.
00:45And because of its characteristics, scientists soon began to wonder if this was, at last,
00:50a visit from otherworldly creatures.
00:55So they went full on with the science fiction suppositions.
00:59Astronomers gathered the information they were sure about.
01:02Starting with the fact that Amuamua must've come from another Solar System.
01:06There must've been some unfortunate event in its home system that led to its ejection.
01:11What they didn't know was that this was a comet or asteroid.
01:15They're both celestial objects orbiting the Sun, but they have distinct compositions
01:19and behaviors.
01:21Comets are composed primarily of ice, dust, and rocky material, often referred to as dirty
01:26snowballs.
01:27When a comet approaches the Sun, the heat causes the ice to vaporize, releasing gas
01:32and dust particles into space.
01:35This creates a bright glowing tail that can extend for millions of miles.
01:40Comets generally have elliptical orbits, often taking them from the distant reaches of our
01:44Solar System closer to the Sun.
01:49Comets, however, are mostly made of rock and metal.
01:52In our neighborhood, they are remnants of the early formation of the Solar System and
01:57are typically found in the asteroid belt between Mars and Jupiter.
02:01Unlike comets, asteroids do not develop tails when they approach the Sun, as they have no
02:06ice.
02:07Their orbits generally follow more circular paths compared to comets.
02:12By all accounts, Amuamua should be a comet, because it seems to come from a different
02:17location in the Universe.
02:20But it doesn't exhibit the typical signs of cometary activity.
02:24Amuamua lacks a tail and does not spew out gas as it passes by, not like me.
02:30Even though it behaves like a comet, it looks more like an asteroid.
02:36Another big question is how scientists even managed to spot Amuamua in the first place.
02:42Considering the vastness of space and time in the galaxy, it's remarkable.
02:46Stars have lifetimes spanning millions or billions of years.
02:50And the formation of a solar system takes hundreds of millions of years.
02:54Even the fastest objects take tens of thousands of years to travel from one star to another.
03:00In contrast, humans have only been observing the skies with telescopes for around 400 years,
03:06a tiny fraction of cosmic time.
03:09And it's only in recent decades, even years, that we've had the technology to detect
03:14and track fast-moving, dim objects.
03:17Either rocks like these are abundant, or we've been incredibly lucky with our detections.
03:22Or it simply wanted to be seen.
03:27Another question that was asked was where such objects could come from.
03:31It's highly unlikely that Amuamua came from a mature, stable solar system.
03:36That's because such systems don't eject enough material to fill up the galaxy.
03:41Occasionally, a random rock might get flung out, but it can rarely travel so far.
03:47Young systems, however, act differently.
03:50In these chaotic environments, collisions, mergers, and migrations are happening everywhere.
03:56Plenty of tiny rocks roam around, perfect candidates for ejection.
04:00The solar system that kicked Amuamua out must've had a planet similar to Jupiter.
04:06Its massive size and gravity could influence other objects in the system, causing potentially
04:11ejections.
04:12But not all solar systems develop Jupiter-sized planets.
04:16Often massive planets end up close to their stars, becoming hotter versions of Jupiter.
04:22These planets, snugly orbiting the Sun, are less likely to eject debris.
04:27Now Neptune-like planets may play a role too.
04:30While not as massive as Jupiter, they tend to call the outer regions of solar systems
04:34their home.
04:36Our solar system has the Kuiper Belt, a reservoir of comets in its outer reaches.
04:41During a solar system's early stages, interactions between Neptune-like planets and debris are
04:46common.
04:47Finding Neptune-like planets in other systems has been challenging though.
04:52Our methods for detecting exoplanets work better for massive objects close to their
04:56stars, making it difficult to spot Neptune counterparts farther out.
05:04Amuamua was also linked to a peculiar theory about how life came to be in the universe
05:09– panspermia.
05:12That's a hypothesis that suggests that life exists throughout the universe and can be
05:16distributed between planets by various means, such as asteroids, comets, or even spacecraft.
05:23It says that life must have originated in one location in the universe and then spread
05:28to other celestial bodies.
05:30Fans of the panspermia theory have suggested that such interstellar objects could potentially
05:35carry tiny microbes – those building blocks of life between star systems.
05:41If such objects were to impact a planet or a moon, they could transfer these materials
05:46and seed the celestial body with life.
05:49For now, there is no evidence to support the theory that this comet in particular has transported
05:54life between star systems.
05:59After years of research, the overall consensus became that Amuamua was indeed a comet.
06:05The reason why it moved so strangely is because it might have frozen hydrogen on its surface
06:10that reacts when touched by sunlight.
06:13The closer it got to our Sun, the faster it became, releasing that hydrogen and also changing
06:18its path through our solar system.
06:21Its color also supports this theory – it's red, which might mean it's been hit by cosmic
06:26rays for a long time.
06:28The longer it was touched by those rays, the more hydrogen it gathered in the process.
06:33But since they can't be completely sure, astronomers have a plan to follow this visitor.
06:39One idea is to send a mission to check it out.
06:42It's already far away from us, but it may not be too late just yet.
06:47We may be able to send a probe fast enough to catch up with the comet.
06:51The plan was named Project Lyra, and aims to use the Earth's orbit and that of Jupiter
06:56to bounce out a probe far enough to reach Amuamua.
07:00If it works, it will be the fastest space device we've sent out in the Universe.
07:05One potential trajectory of the space probe involves the gravitational pull of our planet
07:10and that of Jupiter as a lasso effect, but not Ted Lasso.
07:15The probe will leave our planet and reenter Earth's orbit before sending it to meet
07:19with Jupiter's pull.
07:20It will be sent back near our planet a second time, where it will be ejected with enough
07:25force to reach the comet.
07:30Project Lyra also aims to follow a second faraway visitor, named Borisov.
07:35This one was discovered by an amateur astronomer and now bears his name.
07:39What's interesting about it is that it's, well, spotless.
07:44Similar to our experience with Amuamua, we haven't seen anything like Borisov before
07:48either.
07:50Studies of the light coming from its cloud of dust and gas show it's very clean compared
07:54to other space objects.
07:56After it was first noticed in August 2019, astronomers studied its path through our solar
08:02system and concluded it came from another star too.
08:06But Borisov gave us more time to study it because we spotted it earlier in its journey
08:10through our neighborhood.
08:13Researchers used advanced telescopes to look at the dust coming off Borisov.
08:17They found it's throwing off over 400 pounds of dust every second.
08:22They also found Borisov has more carbon monoxide than comets from our solar system usually
08:27do.
08:28But the amount isn't the same everywhere on the comet.
08:31This tells us the space object probably started forming near its home star before moving away,
08:37maybe because of larger planets in its system.
08:40The light from Borisov is way more polarized than light from other comets we've seen,
08:45and its cloud is super smooth.
08:47This tells us Borisov has never interacted with another star.
08:57That's it for today, so hey, if you pacified your curiosity, then give the video a like
09:01and share it with your friends.
09:03Or if you want more, just click on these videos and stay on the Bright Side!
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