Podcaster: Tony Darnell
Title: Deep Astronomy – Exoplanet Radio – Ep. 42: How Long Will Life on Earth Last?
Organization: Deep Astronomy
Link : https://deepastronomy.space
Twitter @DeepAstronomy, https://facebook.com/DeepAstronomy
YouTube: https://www.youtube.com/deepastronomy
Description: From Oct 9, 2023.
How long before the Earth becomes uninhabitable for all life? This is a reasonable question to ask in the context of our search for life elsewhere because it gives us a framework within which we might expect to discover life on exoplanets. Nothing lasts forever, stars live and die over the course of hundreds of millions to billions, and in the case of red dwarf stars, trillions of years. Planets are born from the remnants of their parent stars and die over a shorter timescale. Life on those planets, if it exists, is presumed to be shorter still, governed entirely by the environments provided by the combination of the star and planetary characteristics. How long life lasts there ultimately depends on how long the star lives and how it dies.
Using our solar system as an example, since we know life arose here, how long will it last? Astronomers think they have an answer.
Bio: Tony Darnell is the owner of Deep Astronomy website and a host for the same hangout channel in Youtube. He has worked in the field of astronomy all my life, his first job was at a school district planetarium in Boulder, Colorado. With the exception of a stint in the Army in the 1980’s he has worked in many aspects of astronomical research.
Most of his time has been spent writing software to retrieve, process and analyze data taken from telescopes. He has worked with data from some of the world’s largest ground-based and space-based telescopes: from the four meter Blanco telescope in Chile to the Hubble Space Telescope.
Astronomy education has always been his passion and he has written articles for DeepAstronomy.space website and produce astronomy videos for YouTube on the DeepAstronomy channel.
Today’s sponsor: Big thanks to our Patreon supporters this month: Paul M. Sutter, Chris Nealen, Frank Frankovic, Frank Tippin, Jako Danar, Michael Freedman, Nik Whitehead, Rani Bush, Ron Diehl, Steven Emert, Brett Duane, Don Swartwout, Vladimir Bogdanov, Steven Kluth, Steve Nerlich, Phyllis Foster, Michael W, James K Wood, Katrina Ince, Cherry Wood.
Please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.
Or please visit our Patreon page: https://www.patreon.com/365DaysOfAstronomy
Transcript:
This is Exoplanet Radio. I’m Tony Darnell.
How long before the Earth becomes uninhabitable for all life? This is a reasonable question to ask in the context of our search for life elsewhere, because it gives us a framework within which we might expect to discover life on exoplanets. Nothing lasts forever.
Stars live and die over the course of hundreds of millions to billions, and in the case of red dwarf stars, trillions of years. Planets are born from the remnants of their parent stars and die over a shorter timescale. Life on those planets, if it exists, is presumed to be shorter still, governed entirely by the environments provided by the combination of the star and planetary characteristics.
How long life lasts there ultimately depends on how long the star lives and how it dies. Using our solar system as an example, since we know life arose here, how long will it last? Astronomers think they have an answer, and it’s not what you think.
Our Sun is a star, and like all stars, it has a lifespan. The Sun is currently in its middle age, but it will eventually get old and die. In about 5 billion years, the Sun will run out of hydrogen in its core and will begin to fuse helium into carbon.
This process will cause the Sun to expand into a red giant star. As the Sun expands, it will engulf Mercury and Venus. It may even reach Earth’s orbit, but it’s not clear whether it will swallow Earth or not.
But well before the Sun reaches this stage, astronomers believe things will get bad for life, probably billions of years before the Sun even reaches the red giant stage. According to some new modeling done by astronomers, in the later phase of the Sun’s life, over the next couple billion years or so, the increasing amounts of energy Earth will receive from the aging Sun will warm its atmosphere. The hotter the atmosphere, the more water vapor it will trap as water evaporates from the Earth’s surface.
The Sun’s ultraviolet rays will break this water vapor down into oxygen and hydrogen, and hydrogen is a gas light enough to escape the atmosphere. With water escaping into space, the oceans will dry up and the crust will dry out, leaving a desolate, uninhabitable world. Astronomers believe that life on Earth will end at least a billion years before the Sun expands into a red giant.
As volcanoes continue throwing carbon dioxide into the atmosphere, there will be no oceans to absorb it or life forms to store it. This buildup of carbon dioxide causes what is called a runaway greenhouse effect, turning the Earth into a hot, dry world like Venus. In fact, Venus may have once hosted a shallow liquid water ocean and temperatures conducive to life before runaway greenhouse processes made its environment unbearable when it was only 2 billion years old.
So in the context of life on other worlds, we need to remember that even though a star might have planets that harbor life, any life that existed there might be long gone, even though the star is still relatively young and has a few billion years left to go. The good news for Earth is that we still have a few billion years before this happens to us. Who knows, humanity might even manage to become a star-traveling civilization capable of stupendous technological marvels that would protect us from a dying Sun.
A billion years is a long time for human beings, even if it is a blink of an eye in a star’s lifetime. Plenty of time to think and plan and dream. Exoplanet Radio is produced by Deep Astronomy.
The music is by Geodesium and available at LochNessProductions.com. Get all episodes at ExoplanetRadio.com or anywhere you get podcasts.
End of podcast:
365 Days of Astronomy
=====================
The 365 Days of Astronomy Podcast is produced by Planetary Science Institute. Audio post production by me, Richard Drumm, project management by Avivah Yamani, and hosting donated by libsyn.com. This content is released under a creative commons Attribution-NonCommercial 4.0 International license. Please share what you love but don’t sell what’s free.
This show is made possible thanks to the generous donations of people like you! Please consider supporting our show on Patreon.com/CosmoQuestX and get access to bonus content. Without your passion and contribution, we won’t be able to share the stories and inspire the worlds. We invite you to join our community of storytellers and share your voice with listeners worldwide.
As we wrap up today’s episode, we are looking forward to unravel more stories from the Universe. With every new discovery from ground-based and space-based observatories, and each milestone in space exploration, we come closer to understanding the cosmos and our place within it.
Until next time let the stars guide your curiosity