If We Want To Find Life-Supporting Worlds, We Should Focus on Small Planets With Large Moons

A rocky planet with a large moon may have good potential to host life, given that the Moon controls essential aspects for life on Earth, including the length of the day, ocean tides, and stable climate. Image Credit: University of Rochester photo illustration by Michael Osadciw featuring Unsplash photography from Brad Fickeisen, Jaanus Jagomagi, and Engin Akyurt

There’s no perfect way of doing anything, including searching for exoplanets. Every planet-hunting method has some type of bias. We’ve found most exoplanets using the transit method, which is biased toward larger planets. Larger planets closer to their stars block more light, meaning we detect large planets transiting in front of their stars more readily than we detect small ones.

That’s a problem because some research says that life-supporting planets are more likely to be small, like Earth. It’s all because of moons and streaming instability.

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Toxic Perchlorate on Mars Could Make Life More Interesting

Credit: Joseph Heili, Tanner Hoog, and Aaron Engelhart

The search for life in the Universe has fascinated humans for centuries. Mars has of course been high on the list of potential habitats for alien existence but since the numerous spacecraft images that have come back showing a barren landscape, it seems Mars may not be so habitable after all. That is, until recently. The Martian regolith, the top layer of dust upon the surface has been found to be full of perchlorate salts.  These chemicals are poisonous to most life on Earth but a new study suggests that some extremophile protein enzymes and RNA may just be able to survive!

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Could Life Exist in Water Droplet Worlds in Venus’ Atmosphere?

Could life exist within Venus' voluminous clouds? New research says yes. Image Credit: Abreu et al. 2024.

It’s a measure of human ingenuity and curiosity that scientists debate the possibility of life on Venus. They established long ago that Venus’ surface is absolutely hostile to life. But didn’t scientists find a biomarker in the planet’s clouds? Could life exist there, never touching the planet’s sweltering surface?

It seems to depend on who you ask.

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Life Might Be Difficult to Find on a Single Planet But Obvious Across Many Worlds

This artist's illustration shows the exoplanet WASP-62B. Searching for chemical biosignatures on exoplanets is a painstaking process, weighed down by assumptions and prone to false positives. Is there a better way to find exoplanets with a chance to support life? Image Credit: CfA

If we could detect a clear, unambiguous biosignature on just one of the thousands of exoplanets we know of, it would be a huge, game-changing moment for humanity. But it’s extremely difficult. We simply aren’t in a place where we can be certain that what we’re detecting means what we think or even hope it does.

But what if we looked at many potential worlds at once?

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What Can Europa’s Surface Tell Us About the Thickness of Its Ice?

Jupiter's second Galilean moon, Europa. Its smooth surface has fewer craters than other moons, but they help us understand its icy shell. (Credit: NASA/JPL/Galileo spacecraft)
The Hubble spotted evidence of geysers coming from Jupiter's moon Europa, but nobody's been able to find them again. (Credit: NASA/JPL/Galileo spacecraft)

You can tell a lot about a planetary body just by looking at its surface, especially if it has craters. Take Europa, for example. It has a fairly young surface—somewhere between 50 and 100 million years old. That’s practically “new” when you compare it to the age of the Solar System. And, Europa’s icy crust is pretty darned smooth, with only a few craters to change the topography.

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Could Earth Life Survive on a Red Dwarf Planet?

This artist's illustration shows planets orbiting a red dwarf star. Many red dwarfs have planets in their habitable zones, but red dwarf flaring might mean those zones aren't habitable at all. New research explores the idea. Image Credit: NASA

Even though exoplanet science has advanced significantly in the last decade or two, we’re still in an unfortunate situation. Scientists can only make educated guesses about which exoplanets may be habitable. Even the closest exoplanet is four light-years away, and though four is a small integer, the distance is enormous.

That doesn’t stop scientists from trying to piece things together, though.

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Cyborg Jellyfish Could Help Explore Oceans Autonomously

A scene from a video about cyborg jellyfish created at Caltech. Courtesy Jahn Dabiri
A scene from a video about cyborg jellyfish created at Caltech. Courtesy Jahn Dabiri

Earth’s oceans are—like space—a largely unexplored frontier. Relatively few humans have explored either place, using specialized life-support equipment. Unlike space, however, the oceans also have other beings that can explore them: jellyfish. They can head to places underwater that humans can never go. That makes them interesting candidates for autonomous ocean exploration.

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Juno Measures How Much Oxygen is Being Produced by Europa

This view of Jupiter’s icy moon Europa was captured by the JunoCam imager aboard NASA’s Juno spacecraft during the mission’s close flyby on Sept. 29, 2022. Image data: NASA/JPL-Caltech/SwRI/MSSS Image processing: Kevin M. Gill CC BY 3.0

If the periodic table listed the elements in order of their importance to life, then oxygen might bully its way to the top. Without oxygen, Earth’s complex life likely would not exist. So when scientists detect oxygen on another world, they turn their attention to it.

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Cosmic Dust Could Have Helped Get Life Going on Earth

This artist’s impression shows dust forming in the environment around a supernova explosion. Credit: ESO/M. Kornmesser

Life on our planet appeared early in Earth’s history. Surprisingly early, since in its early youth our planet didn’t have much of the chemical ingredients necessary for life to evolve. Since prebiotic chemicals such as sugars and amino acids are known to appear in asteroids and comets, one idea is that Earth was seeded with the building blocks of life by early cometary and asteroid impacts. While this likely played a role, a new study shows that cosmic dust also seeded young Earth, and it may have made all the difference.

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Dying Stars Could Have Completely New Habitable Zones

As stars like our Sun age, their habitable zones shift, and they can warm planets that were once frozen. Image Credit: ESO/L. Calçada

Aging stars that become red giants increase their luminosity and can wreak havoc on planets that were once in the star’s habitable zones. When the Sun becomes a red giant and expands, its habitable zone will move further outward, meaning Earth will likely lose its atmosphere, its water, and its life. But for planets further out, their time in the habitable zone will just begin.

Is there enough time for life to arise on these newly habitable planets?

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