The Best Earth-like Exoplanet Has 4 Major Problems

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As telescopes like the James Webb look out  across the Milky Way, you might have heard   the growing buzz around newly discovered  exoplanets. It wasn’t that long ago – only   1992 – that we found the first planet outside  our solar system, but since then over 5,500   have been confirmed in the relatively small area  of space, only a few thousand light-years across,   that we reside in. When the Milky Way  itself is 105,700 light years in diameter,   this offers us a tantalising promise of  billions to trillions more across the rest   of our galaxy. Every star on average likely has  at least one planet, and perhaps has several. With all these exoplanets out there just waiting  to be found, it’s only natural we would want to   turn our thoughts towards goldilocks zones  , and planet habitability. After all,   humanity has its eye on colonising the stars, and  an Earth 2.0 is surely waiting for us out there,   mathematically speaking. In fact, you might  have already heard that phrase “Earth 2.0”   being delivered in headlines of articles  or videos, claiming that a new planet has   been discovered that would be ideal  for human life and colonisation. However, don’t believe the hype. All the  planets we’ve found so far have - to put   it scientifically - sucked. And once  you hear what I’m about to tell you,   you’ll agree that moving to any of them will be  the last thing any sane person would want to do.  I’m Alex McColgan, and you’re watching Astrum.  Join with me today as I give you the grand   real-estate tour on the potential  Earth 2.0’s we’ve discovered so far,   and explain why right now is the wrong time  to get onto the planetary property ladder.  When choosing an Earth 2.0, just like with  buying a house, it’s a good idea to start   by establishing your non-negotiables. Some of  this is fairly simple to consider: for instance,   temperature. You want a nice, temperate  climate, somewhere that’s not too warm,   and not too hot. Given that temperature  drops the further you are from the Sun,   every planetary system has a sweet spot where  the temperature of a planet is likely “just   right” – not too hot, and not too cold – similar  to Goldilocks and her bowls of stolen porridge.   As a rough rule of thumb if a planet is at the  right distance from a star, it may well have   a suitable temperature for us to set up shop. Of course, this is in no way a guarantee. After   all, Venus - a planet residing in this zone -  in theory should be perfect, but its choking   atmosphere makes it the hottest planet in our  solar system in spite of its relative distance   from the Sun compared with Mercury. So it's  clear atmosphere also plays a part in all this Speaking of atmosphere, that’s also something  you’ll want to look for on Earth 2.0 – ideally   something with oxygen and water vapour,  and without anything that would poison us,   but at least something that could trap heat in,  and offer some protection from space radiation. However, sometimes a non-negotiable is simply  the neighbours that live close by. So, let’s   consider the first major reason why the galaxy’s  exoplanets fall short – their neighbouring stars. Our own star is known as a G-type yellow dwarf, a  relatively fast-burning, short-lived sort of star,   at least compared to some of the other options  out there. Stars like our Sun tend to live for   10 billion years before their cores collapse and  they transform into a red giant. It is stable,   and that stability has been useful for the  life that eventually flourished here . However,   yellow dwarfs are far from common in the Milky Way  – they represent only 10% of the total stars. Far   more common in occurrence are the longer-lived  red dwarfs, which make up 75% of the stars in   our galaxy, and can live for around 14 trillion  years, longer than our universe has existed.   And unfortunately for the planets orbiting  them, red dwarfs come with numerous drawbacks. For starters, red dwarfs have a much  closer goldilocks zone compared to their   yellow cousins. They burn less brightly – with  luminosities between 10% and a measly 0.0125%   that of our Sun’s – so unless you want to live  on a world shrouded in perpetual night (which   sounds cold and depressing to me, and will  make growing plants a bit of a challenge),   you’d want an Earth 2.0 to be a lot  nearer to its red dwarf to compensate.  This wouldn’t be in and of itself a  problem, if it weren’t for the second   characteristic of red dwarfs that make them  very unpleasant neighbours – their instability. Our Sun is the main source of our space weather.  It shoots out a frequent stream of solar winds,   flares, and coronal mass ejections. However,  this doesn’t compare to the amount of space   weather created by red dwarfs. Flares from red  dwarfs can be 100 to 1000 times more powerful   than those emitted by our Sun. The frequent  bursts of plasma and radiation coming from   red dwarfs are powerful and dangerous  enough to strip away the atmosphere,   and even boil liquid water on planets  in the habitable zone. And given how   much closer planets are to their star in a  red dwarf system, the odds of life getting   enough time to arise before being hit with  a life-sanitising dose of x-rays is pretty   slim. If you want to live on a planet around a red  dwarf, you’ll likely need some serious sun-cream . This rules out many exoplanets, such as  astronomer favourite Kepler 186 f, which   some scientists hoped might be habitable.  While it may be possible to live for a   time in quite uncomfortable conditions in  a deep underground bunker on such a planet,   the experience would hardly be pleasant. But even  during periods between harsh solar weather events,   there’s another problem with planets around red  dwarfs – their tendency to be tidally locked. Being tidally locked means that the same side of  the planet always faces the star as it orbits.   There is no rotation between day and night –  one side of the planet is in perpetual heat,   and the other side is in permanent shadow.  Due to gravitational constraints, planets   near their sun have a tendency towards being  tidally locked – just take a look at Mercury,   with its days that last 176 Earth-days,  or 2 Mercurian years. This lack of   rotation could render most of the planet  uninhabitable – you’d either face scorching,   desert-creating heat on the day side,  or freezing ice on the night side. Even if humans tried to live in the narrow band of  twilight that would ring a tidally locked planet,   liquid water might prove difficult to find.  Any moisture in the air that found its way   to the night side of the planet would get  locked there, solidified as ice. Overall,   the planet would be very dry; and even in  the twilight zone, there would be no rain. And that’s not to mention the low power of a  magnetic field that would likely be found on   a tidally locked planet. The dynamo effect  that powers the magnetic field on Earth is   thought to be influenced by the Coriolis effect  – the rotation of the Earth imparting momentum   to rising and falling liquid metal  in its core. Without this rotation,   such a magnetic field would be inevitably weaker. So, I’m sorry to say that this rules out planets  such as Proxima Centauri b, our closest exoplanet.   Proxima Centauri b is otherwise an interesting  candidate – its closeness makes it one of the   easiest planets to get to for us, situated only  4.2 light years away. It’s thought to be a rocky,   Earth-like planet, which is convenient, as  living on a gas giant could be challenging   to anyone with a fondness for solid floors  beneath their feet. And most compelling,   its mass and radius are very similar to  Earth’s, meaning it has a similar gravity. Why is this important? Let’s compare  it with another Earth 2.0 contender,   Kepler 452-b. The first planet to  ever be referred to by that title,   and the planet described by a NASA scientist  as “the closest twin to Earth”. Kepler 452-b   has much to recommend it. It is orbiting around  a yellow dwarf, like us, at a similar distance.   This means it’s in the goldilocks zone that makes  liquid water on the surface possible. However,   it is a Super-Earth. This means it has  a mass and radius combination that makes   its gravity about twice that of Earth’s. When it comes to gravity, how much is too   much? Some scientists researching the question  put the figure at 4 times Earth’s gravity,   this being about the limit of what a human could  survive. However, even living in just twice   Earth’s gravity could get rather uncomfortable. To  properly visualise this, or at least get a rough   approximation of it, imagine lying down, but then  imagine a second person lying down on top of you,   putting all their weight onto you. This is your  night, every night. Every breath being fought   for . Come daybreak, you must lift that extra  person up, haul them onto your back, and then   carry them with you everywhere you go. Everywhere.  And be careful not to fall, as suddenly it’s much   easier to break a bone. Falling down stairs  is no longer painful, it’s likely lethal. Everyone must do this. The  elderly. The infirm. Small infants,   trying to take their first, wobbling step. Keeping this in mind, it’s easy to grasp  just how exhausting life in double gravity   might end up being. If you’re a body-builder  or athlete you will likely be all right. But   for most people on Earth, it would be a slow  torture. Your heart furiously beating to move   your blood around, making it feel like  you’re running even when standing still. And if you want to triple the gravity?  Add an additional person on top of that. And things don’t get much better going the other  way. Sure, everything is suddenly much easier,   as that weight is lifted. However, living under  reduced gravity comes with a host of health risks   that we can see from astronauts who’ve spent  just a few months on the International Space   Station. Over time, the calcium bleeds out of  your bones , causing them to become brittle. Your   muscles atrophy. Your heart develops issues. Your  immune system suffers. All told, even if you’re   exercising every day, your long-term prospects  aren’t looking good in a low-gravity environment   – a fact that is challenging NASA scientists  as they try to figure out how to set up human   outposts on places like the Moon, or Mars, where  astronauts might go to live for just a few years. Humans have spent millions of years adapting to  life on our planet. We’re very used to how things   are here. We’re just not suited to anywhere else  – we’ve not evolved to face such conditions. In   some respects it’s a testament to how well we’ve  acclimatised to the environment we were born in,   but it’s a big obstacle if we  ever want to live anywhere else. And so, the hunt for Earth 2.0 goes on. As  I mentioned, there are likely billions of   undiscovered planets in our Milky Way galaxy.  The odds of at least one being out there that   meets our criteria for gravity, temperature, lack  of life-threatening radiation, and presence of   atmosphere and water, are high enough to be a  certainty. Actually finding one that meets the   criteria is a more challenging task, particularly  when most planets are still invisible to even our   strongest telescopes, except for a brief moment  when they pass in front of a convenient star   and block out its light. If someone tells  you that they’ve already found Earth 2.0,   I’d take it with a pinch of salt. We won’t  ever really know that a planet is actually   suitable for human life until we somehow cross the  gulf of space and go there to see it in person.  Of course, until we discover how to do that,  it’s all a bit of a moot question anyway. life has developed on this Earth for millions  of years but we sometimes forget the personal   connection we have to those who've gone on  before have you ever wanted to know their   stories you can thanks to my partner for  today's video my Heritage I have a Canadian   great great grandfather who was born at Sea  and died there he and a boy went fishing one   day and were never seen again although the  boat was later found with giant bite marks   taken out of the side I'd never heard this  story before but I found it as I started to   delve into my family history using my Heritage my  heritage's world leading online service gives you   access to over 19 million historical records  helping you learn about your ancestors and   even discover living relatives you never knew  you had its AI tools like instant discoveries   can help you connect whole branches of your  family tree with just one click and his photo   enhancing tools can repair colorize and even  animate your old images really bringing them   to life if you use my QR code here or Link in  the description below to sign up today you'll   get a 14-day free trial on my Heritage and 50%  off your continuing subscription go on give it a try thanks for watching want to learn more  about how we disc discover exoplanets check   out this video here a big thanks to my patrons and  members if you want your name proudly displayed   at the end of each astram video check out the  links below all the best and see you next time
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Channel: Astrum
Views: 1,500,528
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Keywords: astonomy, Kepler-186f, astrum, super earth, earth 2.0, exoplanet, exoplanets, space tourism, space travel, terraforming, space technology, cosmology, astrophysics, james webb, goldilocks zone, red dwarf, solar flares, space weather, habitable zone, tidally locked, Proxima Centauri b, Kepler 452-b, nasa, gravity, alien life, JWST, james webb space telescope, exoplanet kepler, superhabitable exoplanets, habitable exoplanets, astrumspace, transit method exoplanets, hypothetical scenario
Id: keUZLShfWCY
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Length: 15min 42sec (942 seconds)
Published: Sun Nov 19 2023
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