Better Than Earth? Are There Superhabitable Worlds In The Milky Way?

I've said many times in the past that the earth is the best planet in the universe no matter where we go we'll never find a planet that's a better home to earth life than Earth of course that's because we and all other earth life evolved in this environment evolution adapted us to this planet and it's unlikely we could ever find another planet this good for us however is it the best planet are the places in the universe which might have the conditions for more diversity of life the fact that we have life on Earth at all is pretty amazing we're located in the habitable zone of a main-sequence star that doesn't produce too many killer solar flares we've got a thick atmosphere filled with oxygen and nitrogen that we can breathe the planet is large enough so that it's still molten in its core with a rotating ball of iron that maintains a planetary magnetic field this combined with a thick atmosphere protects the surface of the planet from cosmic rays the worst of ultraviolet radiation from the Sun and deadly solar storms we have plate tectonics that constantly recycle material on the surface of the planet bringing fresh chemicals up from its interior we have a relatively large moon which probably keeps our planet more stable in its axial tilt with tides that helped early life-forms transition from the oceans to the land but not too big a moon we have huge oceans that help regulate the climate of the planet moving warm waters to cooler regions to make them more diverse and habitable the list goes on and I'm sure there are factors that we haven't even discovered yet when it comes to earth life has thrived finding its way into every possible ecological niche adapting itself through evolution to handle bitter cold intense heat the intense pressures at the bottoms of the ocean even cities living right next to human beings but could earth be better it's good to be planets which are super habitable if there's one thing the field of astronomy has taught us it's that we're not special we're not the center of the solar system this isn't a special place or time in the universe and that probably means Earth isn't the best place for life it's the best for humans but not for life according to a paper in 2013 Penn State astrobiologists ravi kumar cooper abu and others calculated where the edges of a star's habitable zone should truly be based on modern climate data they calculated that habitable zone around a sun-like star should be between 0.99 and 1.7 times the distance from the earth to the Sun which means that the earth is actually right on the inner edge of the sun's habitable zone like just barely it was any closer to the Sun we'd experience a runaway greenhouse effect like Venus you probably want to be closer to the middle of the habitable zone where orbital variations won't push your planet into extremes the earth is relatively young considering the fact that the planet has only been around for 4.5 billion years now and figured out multicellular life in the last few hundred million years the Sun is heating up and since we're so close we've actually only got a few hundred million years of billion years of the most before temperatures rise and the oceans evaporate but what if life could have gotten billions of years more evolution to work out new more diverse forms of life you think a platypus is unusual just imagine what you get with 2 billion more years of evolution or 20 billion in a 2016 paper called super habitable worlds Rene Heller and John Armstrong run through the conditions that might make the most habitable possible world and this is a very readable paper with lots of cool ideas so if you're a science fiction writer looking for some world building ideas definitely check it out I'll put a link in the show notes they propose that stars with less mass than the Sun classified as K stars are probably the best candidates for diversity since they're long-lived and relatively stable a K type star will have a lifetime of 20 to 70 billion years without those pesky red dwarf mega flares you'd want other planets in the star system capable of redirecting asteroids and comets with their gravity to deliver water and other chemicals needed for life so thanks for that Jupiter and ideally you want multiple habitable planets in the same system capable of sending life back and forth a process known as panspermia make your habitable planet the moon of a gas giant to get powerful tidal forces that will keep fresh volcanic material erupting to the surface better yet have a binary planet where two worlds orbit one another delivering tidal forces and exchanging life forms back and forth and we're just getting started make the planet bigger and you'll get more surface area for water to circulate temperatures more on that in a second but also more surface area for life-forms to exploit in various niches so we're talking about a bigger more massive planet once you get to about twice the mass of the earth plate tectonics start to shut down so try to stay under that amount you'll toe on a world that's big enough and hot enough in its interior for the movement of iron alloys in its core to maintain a planet-wide magneto sphere you're probably worried about surface gravity but a planet with double the mass of the earth needs only to be about 40 percent larger to have the same surface gravity but it turns out the biggest indicator of a planet's habitability or super habitability might be decided by its oceans and we'll get to that in a second but first I'd like to thank tomislav applause onic jorge fernandez jason Brinkerhoff john keys truck captain stumpy and the rest of our 820 patrons for their generous support educational content should be freely available to anyone in the world and the patrons make this possible join our community at patreon.com slash universe today and get in on the action at a recent conference in Barcelona dr. Stephanie Olson from the University of Chicago presented the work they had done in searching for the environments that would best support life on exoplanets they used a tool from NASA called the rock 3d general circulation model this is a really amazing tool that's freely available to the public you can go to the website and then see what conditions would be like on different worlds from ancient Venus to planets orbitting Proxima Centauri you can simulate their air temperatures rainfall soil conditions and more let me show you some examples here's pre-industrial earth with air temperatures ranging from around 35 degrees Celsius near the equator to colder than minus 60 C at the poles but you can replace the earth with ancient Venus the way the planet looked 2.9 billion years ago when the Sun was 20 percent dimmer than it is today it still rotated once every 243 days though and probably had a shallow ocean that reached a depth of 310 meters across its lowlands here's a planet orbiting the red dwarf star Proxima Centauri the closest star to the Sun because it orbits so closely to the star the planet is probably tidally locked and this has a dramatic impact on the air temperature with one side facing the star and one side facing away but if the planet does have a resonance rotation where it turns three times on its axis for every two orbits and if it has an atmosphere that roughly matches the nitrogen and oxygen atmosphere of Earth then you end up with a world that looks much more comfortable to live on Olson and her team used this software to simulate the climates and ocean habitats of different kinds of exoplanets here on earth the diversity of life depends on the upwelling of material from deep down in the oceans returning it to the surface where life can use it more upwelling means more biological activity more diversity in other words to find the planets with the most diversity of life you want to find the worlds which have strong amounts of ocean circulation so is there anything better than Earth according to Olson if a planet is rotating slowly and has a higher atmospheric density and his countenance you can increase the amount of ocean circulation and this gives us an idea for what astronomers will be looking for as they examine extrasolar world when NASA's levar Havoc's missions fly in the 2030s they'll be able to directly image the surfaces of exoplanets they'll measure the chemicals in their atmosphere detect water and even determine how much of the planet is covered in continents we really shouldn't be surprised if we do find super habitable worlds out there in the Milky Way world's which are clearly more habitable than the earth once again it turns out we're not special that's fine at least we'll have company what do you think let me know your thoughts in the comments here are the names of the patrons who support us at the $10 level and more want to see your name here support the work we do go to patreon.com/scishow universe today once a week I gather up all my space news into a single email newsletter and send it out it's got pictures brief highlights about the story and links you can find out more go to universe today dot-com such newsletter to sign up and did you know that all of my videos are also available in a handy audio podcast format so you could have the latest episodes as well as special bonus material like interviews with me show up right on your audio device go to universe today to calm such audio or search for Universe Today on iTunes Spotify or wherever get your podcasts I'll put a link in the show notes I briefly mentioned the Louvre are and have exhibitions want to know more about these incredible space observatories and what they'll be capable of watch this video next

Channel: Fraser Cain

Views: 73,985

Rating: 4.8764758 out of 5

Keywords: universe today, fraser cain, space, astronomy, earth, planet earth, habitability of earth, atmosphere, superhabitable, the moon, the planets, exoplanets, the Universe, solar heating, age of the earth, multicellular life, habitable planets, panspermia, binary planets, magnetosphere, plate tectonics, circulation model

Id: 7PIxA2-D900

Length: 10min 26sec (626 seconds)

Published: Fri Sep 20 2019