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Extreme environments full of life on Earth have led researchers to expand the definition of habitability to something that includes many more planets, potentially leading us to evidence of living things in a dramatically shorter time! And, in other news, it’s likely that hungry sun-stars have been gobbling planets throughout their lifetimes!

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Sources:
https://www.sciencedaily.com/releases/2021/06/210623113820.htm
https://iopscience.iop.org/article/10.3847/1538-4357/abfd9c
https://www.eurekalert.org/news-releases/926030
https://www.sciencedaily.com/releases/2019/11/191104112437.htm
https://www.nasa.gov/feature/goddard/2021/nasa-s-james-webb-space-telescope-has-completed-testing
https://doi.org/10.1038/s41550-021-01451-8

Image Sources:
https://commons.wikimedia.org/wiki/File:Hubble_Views_a_Dazzling_‘Fireworks_Galaxy’_-_Flickr_-_NASA_Goddard_Photo_and_Video.jpg
https://commons.wikimedia.org/wiki/File:Earth_and_Universe.jpg
https://www.istockphoto.com/photo/blue-red-galaxy-gm606233184-103974849
https://www.eurekalert.org/multimedia/797133
https://commons.wikimedia.org/wiki/File:Neptune,_Earth_size_comparison_2b.jpg
https://commons.wikimedia.org/wiki/File:Oceanplanet_lucianomendez.JPG
https://solarsystem.nasa.gov/resources/17647/earth-undersea-seeps-vents-and-volcanoes/
https://commons.wikimedia.org/wiki/File:Sky_Clouds_and_Atmosphere.jpg
https://commons.wikimedia.org/wiki/File:James_Webb_Space_Telescope_2009_top.jpg
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https://www.nasa.gov/feature/goddard/2021/nasa-model-describes-nearby-star-which-resembles-ours-in-its-youth
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This episode is sponsored by Fabulous, an app  that helps you form healthy habits that stick.

Click the link in the description  to get a free week trial and 25% off a Fabulous premium subscription! [♪ INTRO]. The search for life in the universe  is one of the great quests of science.

But for all the decades we’ve spent searching,  astronomers still don’t really know where to look, or what exactly they should be looking for. After all, Earth is the only place in the cosmos  that we know for certain can sustain life. Hunting for Earth-like planets  is the obvious place to start, but they seem relatively  rare in the nearby universe.

So, in a new paper published last  week in The Astrophysical Journal, researchers from the University of  Cambridge proposed a new approach. They suggested that astronomers expand  their definition of habitability to include planets that are  vastly different from Earth, but that share traits with our  planet’s most extreme environments. The researchers call these planets Hycean  worlds, and they claim that including them in the search for life could lead us to evidence  of living things in a dramatically shorter time.

Hycean planets are larger and  more extreme than Earth-like ones. While Earth and similar planets have a  large, solid core and a moderate temperature, and an atmosphere of nitrogen,  oxygen, and other gases,. Hycean planets don’t have any of that.

They’re closer in size to Neptune, and they trade  our solid surface for one dominated by water and surrounded by an atmosphere of hydrogen. They also have pressures up to a thousand  times higher than our pressure at sea level, and temperatures as hot as 122 degrees Celsius. Their atmospheres can even be  nearly 80 degrees warmer than that.

These conditions might seem extreme, and  sure, they’re not likely to support trees, dogs, and other macroscopic  forms of life as we know it. But we already know that some forms of  life on Earth survive similar conditions, at hydrothermal vents in the Earth’s oceans. These vents are places where seawater  collides with magma from Earth’s mantle, superheating it and creating chemical reactions  that can sustain life far from any sunlight.

In fact, some scientists even believe that life  on Earth actually started in hydrothermal vents. And now, the study’s authors  believe life could potentially arise in similar environments on Hycean planets. Now the advantage of looking for  life on these planets is that sub-Neptune-sized planets seem to  be the most abundant in the galaxy.

With bigger, brighter atmospheres,  they’ll also be easier to probe for the chemical markers of  life, called biosignatures. The biosignatures visible in a hydrogen-rich  atmosphere will be different from those visible on more Earth-like planets,  but the authors found that several signatures should be easily detectable. In fact, one tool capable of  finding that evidence of life,.

NASA’s James Webb Space Telescope,  is slated for launch later this year. So, it’s possible that our first real evidence  of life in the universe is closer than we think. It just probably won’t be  calling us up to say “hello.” While we wait for James Webb to get  underway, let’s unpack a surprising, maybe even disturbing, new discovery: It’s  likely that more than a quarter of Sun-like stars have swallowed at least one  planet in their lifetime.

That’s the conclusion drawn by a new  paper published this week in the journal. Nature Astronomy, and it could  have serious implications for the study of both stars and  the planets that orbit them. Now, one of the basic principles of modern  astrophysics is that the composition of a star records a snapshot of the  environment where it formed.

So, basically, if two stars  formed from the same cloud of gas, they should have virtually  identical chemical compositions. Yet, as telescopes have gotten more sensitive, astronomers have started to notice  that this isn’t always the case. Instead, they’re finding pairs of stars orbiting  each other with distinctly different make-ups.

To take a closer look at this  phenomenon, the authors of this new study examined a sample of 107 pairs of  binary stars with Sun-like properties. In just that one small sample, they identified  33 pairs containing different amounts of iron. Now, without knowing anything else, astronomers  might imagine that those pairs simply formed from clouds of gas that didn’t  have their elements fully mixed.

Like, maybe one star formed out of a clump  that had more or less iron than the other one. But the authors also noticed another clue:. The stars with differing  compositions came almost entirely from the hotter end of the  temperature range in their sample.

And that suggested to them that  something different was going on. See, as a planet approaches its star,  the star’s gravity will tear it apart, sprinkling those planetary  guts all across its surface. But, the cooler a star is, the more efficiently  it recycles material into its interior, where it can’t be seen from Earth.

Basically, cooler stars are better at  hiding the evidence than the hotter ones, so if stars are eating planets,  you would expect to see more evidence of that among the hotter ones. And that’s exactly what researchers  were seeing in their sample. In fact, based on their data, the authors  estimated that around a quarter, or maybe even a third, of Sun-like stars have swallowed  one or more planets in their lifetime.

A fraction that high really challenges  the idea that astronomers can uniquely tie stars to their place  of birth based on their composition. But it also brings us back to the search for life. A star system where planets are being  devoured is probably a pretty chaotic place, which maybe isn’t the best  environment for birthing life.

So, identifying these systems could help  astronomers focus their limited resources on places where living things had a better  chance at avoiding a fiery plunge to their death. And with a challenge as important and  difficult as finding life in the universe, we could use all the help we can get. And finding alien life can be quite a challenge, but it all starts with small steps like creating  habits which Fabulous can help you with!

Fabulous is a self-care and habit-forming  app developed by folks at Duke University’s. Center for Advanced Hindsight  to help support your goals, including making sure you eat your breakfast  before looking for life on other planets! The app is fully customizable, so how  you build your habits is up to you!

It breaks your goals into  very small tasks that you can easily achieve every single  day and at your own pace. With a Fabulous premium subscription,  you can unlock all of their content including daily coach sessions and Journeys. The first 100 people to click on  the link will get a free week trial and 25% off a premium Fabulous subscription!

Which also helps us, so thank you. [♪ OUTRO].