Scientists identify 24 planets potentially better suited for life than Earth
The study identified superhabitable planets outside of our solar system.
07 October, 2020
Credit: sdecoret on Adobe Stock
- The odds are that if Earth had the right conditions for the development of life, other places probably do, too.
- Scientists have identified two dozen planets that match some items on the list of desirable traits.
- All of these planets are too far away to reach with current tech, but may be valuable research targets.
<p>It's called the "<a href="https://bigthink.com/experts-corner/seeing-earth-from-space-how-true-awe-changes-you" target="_self">overview effect</a>." You know, the renewed appreciation and protectiveness that astronauts orbiting the globe come to feel looking down on our precious Earth. The sense of profound awe and gratitude that we find ourselves in a place so special among the cold, vast emptiness of space. Now a study from Washington State University (WSU) says there are lots of planets out there better than this one.</p>
Superhabitable
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ3MzYwNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMjYwOTE5NX0.7WH5907n-K3Ew9QP96D1ohm_yUDEcwH_XjnDwnICYQM/img.jpg?width=980" id="206f9" class="rm-shortcode" data-rm-shortcode-id="ef375f57087011a2324d7f086e3b96c1" data-rm-shortcode-name="rebelmouse-image" />The 24 candidates in their habitable zone near K dwarf stars
Credit: Schulze-Makuch, et al./Astrobiology
<p>On the other hand, all that desirable real estate is pretty far away — none of these 24 "superhabitable" planets are less than 100 million light years from Earth. They were identified in a study led by geologist <a href="https://news.wsu.edu/tag/dirk-schulze-makuch/" target="_blank" rel="noopener noreferrer">Dirk Schulze-Makuch</a> of WSU and Technical University in Berlin, Germany. He was joined in the research by astrophysicists <a href="https://www2.mps.mpg.de/homes/heller/" target="_blank">René Heller</a> of the Max Planck Institute for Solar System Research in Germany and <a href="https://www1.villanova.edu/villanova/artsci/astronomy/meet_us.html?mail=edward.guinan@villanova.edu&xsl=bio_long" target="_blank">Edward Guinan</a> of Villanova University.</p><p>The open-access study is published in the journal <a href="https://www.liebertpub.com/doi/10.1089/ast.2019.2161" target="_blank">Astrobiology</a>.</p><p>Ignoring the possibility that other planets might be even more likely to support life than ours is, after all, like someone insisting they live in the best country in the world without having visited any others. The study puts it this way: "Neglecting this possible class of 'superhabitable' planets, however, could be considered anthropocentric and geocentric biases."</p><p>In searching for superhabitable planets among the 4,500 known candidates, the scientists were not so much looking for somewhere for us to escape to as they were spotting planets that were most likely to be populated by intelligent life. Their hope is to offer up interesting targets for future investigation by instruments such as the European Space Agency's <a href="https://sci.esa.int/web/plato" target="_blank" rel="noopener noreferrer">PLATO space telescope</a>, as well as NASA's <a href="https://www.jwst.nasa.gov" target="_blank">James Webb Space Telescope</a> and <a href="https://asd.gsfc.nasa.gov/luvoir/" target="_blank" rel="noopener noreferrer">LUVOIR space observatory</a>.</p><p>Schulze-Makuch tells <a href="https://news.wsu.edu/2020/10/05/planets-may-better-life-earth/" target="_blank">WSU Insider</a>:</p><p style="margin-left: 20px;">"With the next space telescopes coming up, we will get more information, so it is important to select some targets. We have to focus on certain planets that have the most promising conditions for complex life. However, we have to be careful to not get stuck looking for a second Earth because there could be planets that might be more suitable for life than ours."</p><p>Before one can go searching for superhabitable planets, once must figure out what that word means.</p>Blame it on the sun
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ3MzYxNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2NjAwNDUyNn0.bv9FioVLoHPE7IxjWnmRzfNKkeGI6UOioEorxSqMapU/img.jpg?width=980" id="7f28c" class="rm-shortcode" data-rm-shortcode-id="5613866aa3c976f165e51f4565517e90" data-rm-shortcode-name="rebelmouse-image" />Credit: Tungdil Preston/Unsplash
<p>The scientists first had to work out the type of sun a superhabitable planet would be most likely to orbit. Interestingly, they decided against dwarf type G stars — also known as "dG stars" — similar to our own sun. After all, they write, "Since it took about 3.5 billion years on Earth until complex macroscopic life appeared, and about 4 billion years for technologically advanced life (us), life on many planets orbiting dG stars may simply run out of time."</p><p>Another issue is that young dG stars spin 10 times as fast as our mature Sun now does, producing "high levels of magnetic dynamo-driven activity and very intense coronal X-ray and chromospheric FUV emissions, which makes the origin and early evolution of life challenging."</p><p>The study settles on planets orbiting type K stars. These stars are a bit cooler than ours and less luminous, but they live a long time, longer than the Sun, from 20 to 70 billion years. This would give their planets more time to get life going.</p>Size matters
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ3MzYxNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNjkxMzg4Nn0.x8YqDvGmdmooMUSRu7oJCGTKiwg5VPrqZaoboVOa5fQ/img.jpg?width=980" id="f48b4" class="rm-shortcode" data-rm-shortcode-id="372b444990b8ca7a2520d3bca8124851" data-rm-shortcode-name="rebelmouse-image" />Credit: AleksandrMorrisovich/Shutterstock
<p>Planets with a greater mass than ours were deemed desirable for a few reasons, so long as they were not so big as to become gas giants and so on. These planets would have robust, thick atmospheres, slightly higher temperatures for nurturing life, and lots of elbow room: "This would have advantages for the distribution of species and settlements of islands and continents."</p>Environmental requirements
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ3MzYyNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MjQ4NzM5Mn0.9dDvWvYfJY63wX2QbZ0SnITCtsSAMzAoK0H4pfG7D8Q/img.jpg?width=980" id="d973e" class="rm-shortcode" data-rm-shortcode-id="b2e925bc9949378ce37bbc318ff35493" data-rm-shortcode-name="rebelmouse-image" />Credit: BeeBright/Shutterstock
<p>The researchers also settled on an environmental checklist for superhabitable planets. Based on the conditions that allowed life to form on Earth, a planet would have to have the following life-supporting conditions as explained in the study:</p><ul><li><em>T</em><em>emperatures</em> —"Submarine hydrothermal systems, geothermal hot springs, brine pockets in sea ice at about −30°C, deep continental areas"</li><li><em>pH</em> — "Acid mine drainage, geothermal sulfurous sites (e.g., Yellowstone) Soda lakes, peridotite-hosted hydrothermal systems (e.g., Lost City vent)"</li><li><em>Water activity</em> — "Deep-sea brines, soda lakes, evaporate ponds, dry soils and rocks, food with high solute content"</li><li><em>Lower O2 content </em>— "Anoxic marine or lacustrine sediments, intestinal organs, early Earth environments"</li><li><em>Pressure</em> — "Deep oceanic trenches such as the 11,100 m deep Marianas Trench, Martian surface conditions (based on laboratory experiments)"</li><li><em>Radiation</em> — "No natural source of radiation on Earth at levels tolerated by D. radiodurans"</li><li><em>Chemical extremes</em> — "Submarine hydrothermal vent fluids and sulfides; some high-metal containing lakes"</li></ul>We have some winners. Sort of.
<p>Of the superhabitable candidates the study detected, none totally meet the researchers' criteria, though one has four of them, meaning it may be more likely to have life on it than Earth did, and it might be a place we could consider quite comfy.</p><p>Concludes Schulze-Makuch, "It's sometimes difficult to convey this principle of superhabitable planets because we think we have the best planet. We have a great number of complex and diverse lifeforms, and many that can survive in extreme environments. It is good to have adaptable life, but that doesn't mean that we have the best of everything."</p>
Keep reading
Show less
Venus' clouds may harbor 'aerial' aliens, MIT scientists say
Scientists have detected within the Venusian atmosphere a chemical known to be a byproduct of life.
14 September, 2020
NASA
- A team of researchers has detected significant amounts of phosphine within the cloud deck of Venus.
- Computer simulations suggest that the amount of phosphine in the Venusian atmosphere couldn't have been produced by known inorganic processes.
- The findings aren't conclusive evidence of alien life, but they do suggest Venus shouldn't be overlooked in the search for alien life.
<p>The skies of Venus may contain signatures of alien life, according to scientists at the Massachusetts Institute of Technology.</p><p>In the search for alien life, the second planet from our Sun has long been ignored. It's easy to see why: the Venusian surface reaches temperatures exceeding 800 degrees Fahrenheit; its dense atmosphere applies nearly 100 times more pressure to objects than Earth's atmosphere; and the planet rains sulfuric acid, a corrosive chemical that causes severe burns to humans. </p><p>As such, most scientists have focused on finding signs of ancient alien life on Mars, or current life on moons like Europa or Enceladus. But Earth's closest neighbor might have been the place to look all along.</p><p>A new paper published in <a href="https://www.nature.com/articles/s41550-020-1174-4" target="_blank">Nature Astronomy</a> shows that the Venusian atmosphere seems to contain significant amounts of phosphine, a chemical that's known to be a byproduct of life. </p>
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDIzMzMxNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxODM5MjI2OH0.CWvof-T-U8AzPU4dY_mwbzjXuwvrrRTdtGMy_m8FMtc/img.jpg?width=980" id="91622" class="rm-shortcode" data-rm-shortcode-id="446bd597fa886729323e612f09844141" data-rm-shortcode-name="rebelmouse-image" alt="Pioneer Venus orbiter" />
Pioneer Venus orbiter illustration
NASA
<p>It's not conclusive evidence of life: Phosphine (PH3) can be produced through inorganic processes, like interactions involving sunlight, surface minerals, volcanic activity, and lightning. </p><p>But the study authors considered these and other potential sources, and they created computer models to test whether they could simulate the production of phosphine on Venus. The results produced small amounts of the chemical, but not nearly as much as multiple observatories have detected within the cloud decks of Venus.</p><p>So, for now, scientists don't know what's producing the phosphine. Alien life remains a plausible explanation.</p><p style="margin-left: 20px;">"Technically, biomolecules have been found in Venus' atmosphere before, but these molecules are also associated with a thousand things other than life," study co-author Clara Sousa-Silva told <a href="https://news.mit.edu/2020/life-venus-phosphine-0914" target="_blank">MIT News</a>. "The reason phosphine is special is, without life it is very difficult to make phosphine on rocky planets. Earth has been the only terrestrial planet where we have found phosphine, because there is life here. Until now."</p><span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="9e6f888282e9013b4886a9c13b893e57"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/X57ebvnkwxQ?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>If life really is producing the chemical, it's likely anaerobic life, which are organisms that don't require oxygen. Interestingly, such lifeforms would probably be "aerial" aliens, floating within a relatively thin slice of habitable atmosphere, surrounded by otherwise hellish conditions. </p><p>How would those lifeforms have gotten there? Sousa-Silva explained:</p><p style="margin-left: 20px;">"A long time ago, Venus is thought to have oceans, and was probably habitable like Earth," Sousa-Silva told MIT News. "As Venus became less hospitable, life would have had to adapt, and they could now be in this narrow envelope of the atmosphere where they can still survive. This could show that even a planet at the edge of the habitable zone could have an atmosphere with a local aerial habitable envelope."</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="d633dd0ed7bf23aecb6d87a734db2f79"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/4Z9rM8ChTjY?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>The researchers emphasized that the detection of phosphine in the Venusian atmosphere isn't necessarily evidence of life, but rather of "anomalous and unexplained chemistry." Still, they hope to confirm their findings with additional observations, including a potential probe mission, which would be NASA's first since <a href="https://en.wikipedia.org/wiki/Pioneer_Venus_Multiprobe" target="_blank" rel="noopener noreferrer">Pioneer Venus 2</a> entered the Venusian atmosphere in 1978.</p>
Keep reading
Show less
NASA scientists propose sending a submarine to explore Titan's seas
The mission could launch as soon as the 2030s, the researchers said.
28 August, 2020
- A team of scientists have been developing a proposal that would send a semi-autonomous submarine to explore the seas of Titan, Saturn's largest moon.
- Titan is the only body in our solar system that has large bodies of liquid on its surface.
- It's also a top candidate in the search for alien life.
<p>What lies in the alien seas of Titan, Saturn's largest moon?</p><p>To find out, a team of researchers has spent years developing a plan that would send a submarine to explore the moon's extremely inhospitable lakes and seas, potentially as soon as the 2030s. NASA hasn't approved the mission, but the agency has granted the researchers two rounds of funding through the Innovative Advanced Concepts (NIAC) program. </p><p>If approved, the mission would be a massive undertaking, requiring the transport of a semi-autonomous, nuclear-powered submarine that's 20 feet long and 3,300 pounds on a seven-year journey to Saturn. </p><p>In a NASA blog <a href="https://www.nasa.gov/content/titan-submarine-exploring-the-depths-of-kraken/" target="_blank" rel="noopener noreferrer">post</a>, Steven Oleson of NASA's Glenn Research Center wrote:</p><p style="margin-left: 20px;">"The mission concept we propose to study will investigate a full spectrum of oceanographic phenomena: chemical composition of the liquid, surface and subsurface currents, mixing and layering in the 'water' column, tides, wind and waves, bathymetry, and bottom features and composition."</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="bdd49b8d4757a9ff3f7601542091ac27"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/NnKxbdpLP5E?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>Later in the post, Oleson added that the mission could help scientists better understand how life evolved on Earth, and potentially on Titan. In a presentation with NASA's Future In-Space Operations working group earlier this month, Oelson <a href="https://www.space.com/26444-saturn-moon-titan-salty-ocean.html" target="_blank" rel="noopener noreferrer">said</a>:</p><p style="margin-left: 20px;">"We feel that the Titan submarine is kind of a first step before you go do a [sub mission on] <a href="https://www.space.com/15498-europa-sdcmp.html" target="_blank" rel="noopener noreferrer">Europa</a> or <a href="https://www.space.com/20543-enceladus-saturn-s-tiny-shiny-moon.html" target="_blank" rel="noopener noreferrer">Enceladus</a>."</p>
Why study Titan?
<p>Titan has long been a top candidate for space research and the search for alien life within our solar system. But scientists didn't know much about the Mercury-sized moon until 2004, when NASA's Cassini spacecraft began conducting flybys of Titan, and later landed the <em>Huygens </em>probe on the moon's surface.<br></p><p>That mission revealed that Titan is actually more like Earth than our Moon: Titan has an atmosphere with organic molecules and complex chemistry. It has rain and <a href="http://spaceref.com/saturn/violent-methane-storms-on-titan-may-explain-dune-direction.html" target="_blank">storms</a>, which help to shape the dunes on its surface. And it has maria (seas) and lacus (lakes), some larger than the Great Lakes of North America. Besides Earth, no other body in our solar system has liquid on its surface like Titan does.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzU5NDcxOC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0Mzc3NDAzMX0.VRspWmfjD3xF56JwnwhNBz_cPtZFXthXaHfXmylmthI/img.jpg?width=980" id="e62c6" class="rm-shortcode" data-rm-shortcode-id="af1fe692aa26e6e27044916ca6b702ea" data-rm-shortcode-name="rebelmouse-image" alt="Titan" />
Titan
<p>Still, it might be more accurate to think of Titan as a "deranged Earth," as Caitlin Griffith, a professor in the UA Lunar and Planetary Laboratory, put it to <a href="https://www.forbes.com/sites/jamiecartereurope/2019/04/30/welcome-to-titan-saturns-deranged-earth-like-moon-beginning-to-show-signs-of-life/#3b613d8bf1a6" target="_blank">Forbes</a>. After all, Titan's orangeish atmosphere is incredibly smoggy, made mostly of nitrogen and a bit of methane. Its surface is incredibly cold, at about -290 degrees Fahrenheit. And its frigid seas are made of ethane or methane, not water.</p><p>But the strange composition of Titan's seas might not be a bad thing: It should be relatively easy for a submarine to travel through Titan's seas, and the salty liquid wouldn't interfere with radio signals. (Depending on the mission design, those signals would be beamed directly to Earth, or to a relay orbiter outside of Titan.)</p><p>The submarine would likely explore two of Titan's largest northern seas, Kraken Mare and Ligeia Mare, which cover thousands of square miles and reach depths of 115 feet and 560 feet, respectively.</p><span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="f2a381b9eaba2079fec65fd237bc730d"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/P7rVj_XbDnU?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>It's unclear what the submarine might find. Organisms as we know them on Earth would have a tough time surviving in Titan's seas, but scientists do generally agree that it's possible the moon may harbor microbial life.</p><p>If the mission is approved, the submarine would likely need to reach Titan during the moon's spring or summer, when there's visible light. Given that each of Titan's seasons last about seven years, that means the submarine would need to launch in the 2030s, if it's going to happen in the mid-term future. </p><p>In 2026, NASA plans to launch a rotorcraft to Titan as part of a separate mission.</p><p style="margin-left: 20px;">"With the Dragonfly mission, NASA will once again do what no one else can do," <a href="https://www.nasa.gov/press-release/nasas-dragonfly-will-fly-around-titan-looking-for-origins-signs-of-life" target="_blank">said</a> NASA Administrator Jim Bridenstine. "Visiting this mysterious ocean world could revolutionize what we know about life in the universe. This cutting-edge mission would have been unthinkable even just a few years ago, but we're now ready for Dragonfly's amazing flight."</p>
Keep reading
Show less
Mars colony: Humanity's greatest quest
Just how close are we to setting up camp on another planet? It's complicated.
19 August, 2020
- We are closer than ever to actually putting human beings on Mars, but exactly how close is very much still up for debate. Getting there is one thing, and we eventually may not have a choice, but there are a number of problems that need to be solved before our species can call the Red Planet home.
- In this video, former NASA astronaut Leland Melvin, educator Bill Nye, science journalist Stephen Petranek, astronomer Michelle Thaller, and theoretical physicist Michio Kaku consider mankind's fascination with Mars and explain why the planet may be the most viable option for colonization. They also share difficult truths about what it will take for this expensive dream to become a reality.
- From finding a way to protect against radiation and adjusting to the difference in atmospheric pressure, to mining for ice and transporting food, to significantly lowering the cost of space travel, it certainly won't be easy. But that doesn't mean that it's not worth doing. As Leland Melvin says, the spirit of exploration and curiosity is in our DNA.
The biology of aliens: How much do we know?
Hollywood has created an idea of aliens that doesn't match the science.
05 July, 2020
- Ask someone what they think aliens look like and you'll probably get a description heavily informed by films and pop culture. The existence of life beyond our planet has yet to be confirmed, but there are clues as to the biology of extraterrestrials in science.
- "Don't give them claws," says biologist E.O. Wilson. "Claws are for carnivores and you've got to be an omnivore to be an E.T. There just isn't enough energy available in the next trophic level down to maintain big populations and stable populations that can evolve civilization."
- In this compilation, Wilson, theoretical physicist Michio Kaku, Bill Nye, and evolutionary biologist Jonathan B. Losos explain why aliens don't look like us and why Hollywood depictions are mostly inaccurate.
<div></div><ul class="ee-ul"></ul><div><br></div>
Keep reading
Show less
Popular
