Did We Just Discover a Planet That's BETTER Than Earth? | Unveiled - video Dailymotion

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00:00 Planet Earth has been home to life for an estimated 3.7 billion years, and now hosts

00:05 8.7 million species of animals and plants.

00:09 Naturally, we have long wondered if other planets in the universe could similarly harbour

00:13 life.

00:14 In the search for such planets, researchers strive to find the ones most similar to Earth…

00:19 but some wonder if our little blue dot isn't the best there is, and theorise that we could

00:24 soon find something even better.

00:27 This is Unveiled, and today we're answering the extraordinary question; did scientists

00:31 just find planets that are better than Earth for life?

00:35 Do you need the big questions answered?

00:37 Are you constantly curious?

00:38 Then why not subscribe to Unveiled for more clips like this one?

00:41 And ring the bell for more thought-provoking content!

00:44 There's only one planet that we're certain has life, and that's our home, Earth.

00:49 Since at least the era of classical antiquity over two millennia ago, humans have pondered

00:54 the possibility of life on other worlds.

00:57 The famed Greek philosophers Democritus and Epicurus, who held that everything was composed

01:02 of infinite atoms in an infinite void, believe there must be other, similar worlds out there.

01:08 According to Epicurus' disciple, Metrodorus of Chios, if our world was the only one, it

01:14 would be like a single ear of wheat growing on a vast plain.

01:19 Of course, this was long before the invention of the telescope, making the idea quite abstract

01:24 for the time.

01:25 It came at a time when the dominant view was still geocentric, putting the Earth at the

01:29 centre of the universe.

01:30 Now we're closer to finding extraterrestrial life than ever before.

01:34 The international search effort has been well underway since the 1980s, utilising a plethora

01:40 of advanced tools, from radio telescopes to infrared instruments on satellites.

01:45 We have currently over 5,500 confirmed discoveries of exoplanets.

01:51 Most of these were discovered by the Kepler Space Telescope, and are all compiled in NASA's

01:56 Exoplanet Archive.

01:57 Once catalogued, they are assessed for habitability, and if there's potential, they're added

02:02 to the Habitable Exoplanets catalogue.

02:04 This work is carried out primarily by the Planetary Habitability Laboratory at the University

02:09 of Puerto Rico in Arecibo.

02:12 What they look for first is if the exoplanet has the conditions needed for liquid water

02:16 on the surface.

02:18 The range around a star where planetary orbits are ideal for liquid water is called the "habitable

02:23 zone", or the "Goldilocks zone".

02:26 This is thought of as the most important requirement, since on Earth, where there is water, there

02:31 is life.

02:32 It's assumed that if a world can support liquid water, life won't be too far away.

02:37 There are numerous other factors that need accounting for, however, such as radiation

02:41 from the host star, and atmospheric composition, alongside various geophysical factors.

02:48 All exoplanets on the catalogue are assigned an Earth Similarity Index, or ESI.

02:53 This number ranges from zero to one, with zero meaning no similarities and one being

02:59 identical.

03:00 The rationale for this is that Earth is the only place we know life exists.

03:04 Thus, researchers think that the closer an exoplanet is to our home, the stronger the

03:08 chance of life.

03:10 Not all astronomers are in agreement on this, however, and in the past decade some have

03:14 argued that the assumption is misguided.

03:17 While Earth is indeed a hotspot for life, we can't be certain that it is the most ideal

03:21 home for life.

03:22 It's often said by astronomers that the more you learn about Earth, the more you realise

03:26 just how lucky we are to be here.

03:29 It's not just liquid water that makes our planet a paradise; there are also an abundance

03:33 of other factors.

03:35 For example, the magnetic field that absorbs most of the sun's harmful ultraviolet radiation,

03:40 or the tectonic plates that form continents and bring heat to the surface.

03:44 We also can't forget Jupiter, whose gravity may capture asteroids and comets hazardous

03:50 to life.

03:51 So, there are good reasons to describe our home as perfect for life.

03:55 However, in 2014, physics professor John Armstrong and astrophysicist Renee Heller challenged

04:01 this claim.

04:02 They proposed that certain kinds of planets with characteristics very different to Earth

04:07 could be even more habitable.

04:09 In fact, could be what they call "superhabitable".

04:12 They define "superhabitable" as a planet that can sustain a more diverse selection

04:17 of plants and animals.

04:18 The researchers still assume that life needs water, but believe that there could be planets

04:23 better optimised than Earth for biodiversity.

04:26 They reject the idea that the Goldilocks Zone is a good indicator of habitability.

04:31 A lot of Rocky World's inhabitable zones aren't habitable.

04:35 And geothermal processes can make planets outside of the zone habitable.

04:40 One such example is Jupiter's icy moon, Europa.

04:43 While its surface is covered in ice, scientists believe that a subsurface ocean is hiding

04:48 below, kept warm by tidal heating.

04:51 According to Heller and Armstrong, the search for extraterrestrial life should be less human-centric

04:57 and more biocentric.

04:59 Biodiversity criteria should include a planet's age, mass, location in its system, host star's

05:05 spectral type, and a few other features.

05:08 The concept isn't limited to just exoplanets, but also includes exomoons.

05:13 Superhabitable planets, the researchers suggest, are likely slightly larger, more massive,

05:18 and older than Earth.

05:20 A larger surface area would allow for more shallow seas, which warm more easily than

05:25 deep oceans, making them comfortable habitats.

05:28 In terms of mass, the ideal would be roughly twice Earth's - optimal for plate tectonics,

05:33 a strong magnetic field, and a thick atmosphere.

05:37 Created by the rotation of a liquid outer core, Earth's magnetic field shields us

05:41 from cosmic radiation.

05:43 Theoretically, a more massive world could have a stronger magnetosphere, a thicker atmosphere

05:48 would make the surface warmer, and historically, warmer epochs on Earth have encouraged biological

05:54 diversity.

05:55 Ideally, a superhabitable planet should orbit a different kind of star to the sun.

06:00 The sun is a yellow dwarf, but orange dwarfs, which have lower luminosities and are less

06:05 massive, have significantly longer lifespans.

06:09 Called K-type main-sequence stars, orange dwarfs remain stable for 17 to 70 billion

06:15 years - far longer than our sun's 10 billion year shelf life.

06:19 This would allow more time for life to originate and evolve.

06:23 As a bonus, they emit much less UV radiation, too.

06:26 Currently, there are 24 exoplanets deemed potentially superhabitable, although only

06:31 two of these are validated planets.

06:34 However, it's thought that there might also be other contenders already catalogued and

06:39 overlooked.

06:40 This leads us to ask the exciting question, what would life be like on such a planet?

06:45 Of course, we can only speculate about the specifics, but rainfall would likely be more

06:49 common… and native flora very different.

06:52 With a denser atmosphere and higher mass, life might be larger and more common.

06:57 Plants might follow different processes of photosynthesis, due to the different spectral

07:02 output of other host stars.

07:04 Orange dwarfs are cooler and redder than the sun, and plants might evolve pigments optimized

07:10 to absorb those wavelengths.

07:12 Their leaves might be blue, or some other color, rather than green.

07:16 If we managed to discover a superhabitable planet, it would have major implications.

07:21 After one thing, it could provide invaluable insight into the hypothetical "Great Filter".

07:26 This is the theory that life is rare in the universe, because there's some unknown barrier

07:30 between the earliest stages and the highest levels of development.

07:34 Perhaps, for example, life tends to destroy itself.

07:37 Or, the universe, with its asteroids and rogue black holes, is far more dangerous than we

07:42 think.

07:43 We're currently unsure whether such a Great Filter exists at all, and whether it's behind

07:47 or ahead of us.

07:49 Life on a superhabitable world could shed some light on this topic.

07:53 If we find that life tends to get stuck in its simplest form, that barrier might be behind

07:58 us.

07:59 If, on the other hand, we find a planet teeming with complex life, having comfortably survived

08:04 for billions of years, well, maybe we should figure out how they did it.

08:08 Perhaps, they had no desire to leave their homeworld, and avoided some risk of collapse

08:12 inherent in interplanetary expansion.

08:15 Alternatively, we might find the ruins of a once-great extraterrestrial civilization,

08:20 which could also suggest some answers.

08:23 Both scenarios would put the barrier ahead of us, and give us some idea of what to watch

08:27 out for.

08:28 What do you think?

08:29 Is there anything we missed?

08:30 Let us know in the comments, check out these other clips from Unveiled, and make sure you

08:34 subscribe and ring the bell for our latest content.

Did We Just Discover a Planet That's BETTER Than Earth? | Unveiled

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