Category: astrobiology

10 Surprising Places In Space With The Right Raw Ingredients For Life

“Shortly after Earth first formed first formed, life quickly took hold, thriving ever since. Perhaps terrestrial life didn’t originate here, but arrived from elsewhere through natural processes. Surprisingly, the raw ingredients necessary for life exist almost everywhere astronomers look. Here are 10 locations where they’re ubiquitous.”

It’s not surprising to find that the ingredients for life are found in locations all over planet Earth. But what might be surprising is the sheer number and variety of places in the Universe, far beyond our planet, where the necessary raw ingredients are also found. I don’t just mean atoms, but complex organic molecules like ethyl formate, cyanopolyynes, fullerenes, amino acids, and even proteins. You can find them in meteorites, on Pluto, Mars, around newly forming stars, in reflection nebulae, in dark gas clouds in the galaxy, and even in the galactic center, among many other locations.

Here are 10 surprising places in space that all have the right raw ingredients for life. Perhaps, if the ingredients are all over, life in the Milky Way is, too.

Will Alien Life First Be Discovered On Europa, Exoplanets, Or From Extraterrestrials?

“If it exists on a world in our Solar System, like Mars or Europa, we’ll finally be sending space probes with the capability of finding those biosignatures. If life exists and has thrived for a long time on a nearby exoplanets, direct imaging or transit spectroscopy could reveal hints or even surefire evidence of that planetary transformation. And if intelligent aliens are trying to contact us, we’re better positioned to pick up those beacons than ever before.

For as long as humans have existed, we’ve wondered whether life on Earth is all there is and if we’re alone in the Universe, or if other life forms exist on worlds beyond our own planet. As the 2020s dawns, we have better prospects than ever for discovering life on all three possible fronts. With billions of potentially inhabited worlds in our galaxy alone, even if life is relatively rare, we’re still in great position to detect what scant life does exist. Arguably, the biggest question isn’t whether we’re alone or not, but rather how and where we’ll find our first evidence for life beyond Earth.”

It’s the start of the 2020s, and humanity still hasn’t determined whether we’re alone in the Universe or not. We’ve never found a single surefire signature of the existence of extraterrestrial life: not in our solar system, not on planets around other stars, not from intelligent, spacefaring aliens. But if there are alien life forms out there, inhabiting other planets and leaving their biological imprints on them, we have three entirely unique and complementary approaches to uncovering them.

So how will we get there first? Come explore the possibilities and see where the technology will take us this decade!

Ask Ethan: Would An Alien Civilization Classify Earth As An ‘Interesting’ Planet?

“I was thinking about the projection of light through space. My curtain was open and I saw the stars and something from a book popped into my head. It had said that the stars we see are basically reruns. The light is from so long ago, we don’t even know if the star still exists or not.

[…] Whatever signals we send out, or changes in our planet that might be observable to prove intelligent life lives here, would take billions of years to reach anything alive and capable of responding! What do you think?”

The cosmic distances separating the stars and galaxies are absolutely tremendous, and even though the speed of light is the fastest speed there is, it still takes an awfully long time to traverse the astronomical abyss of space. Humanity has only been a technologically advanced civilization for a few hundred years, and we’ve only entered the space age a few decades ago. Yet that doesn’t mean we’re off-limits to advanced aliens who might be looking for us at all. Even if they couldn’t discover our technosignatures, they could still tell, even from billions of light-years away, that Earth was an interesting, inhabited planet, using nothing more than more advanced versions of the technologies we’re using today and in the near-future to look for life on exoplanets in our cosmic backyard.

An alien civilization with more advanced technology could detect cosmically interesting things about Earth from extremely far away. Here’s where your hopes and fears meet with reality: on this week’s Ask Ethan!

What Was It Like When Venus And Mars Became Uninhabitable Planets?

“But the changes that Mars endured were rapid and sweeping. Planets are born with a fixed amount of internal heat, which radiates away over their lifetime. A planet like Mars, with half the diameter of Earth, is born with only about 10-15% the amount of internal heat as our world, and will therefore see a greater percentage of it radiate away much faster than Earth will.

Approximately 3 billion years ago, the core of Mars became cool enough that it stopped producing that protective magnetic dynamo, and the solar wind began striking the Martian atmosphere. In short order, which is to say in just tens of millions of years, the atmosphere was knocked off into interplanetary space. As a result, the oceans were unable to remain in liquid form, and either froze beneath the surface or sublimated away.”

When our Solar System first formed, it wasn’t just Earth that looked promising for life, but also Venus and Mars. All three of these planets had large, liquid water oceans, substantial atmospheres, and the ingredients for complex biochemistry and even life. Over on Venus, its close proximity to the Sun and the large presence of atmospheric water vapor led to a runaway greenhouse effect, boiling the oceans after just ~200 million years. But Mars, despite being small and distant, maintained Earth-like conditions for 1.5 billion years. Considering that life arose on Earth after just one-sixth of that duration, perhaps Mars once had life, too?

Come get the story of the Solar System’s closest version of a failed version of Earth, Mars, and learn how it ultimately lost its chance at habitability.

Aliens? Or Alien Impostors? Finding Oxygen Might Not Mean Life, After All

“This doesn’t mean that finding an Earth-like world with an oxygen-rich atmosphere won’t be incredibly interesting; it absolutely will be. It doesn’t mean that finding organic molecules coincident with the oxygen won’t be compelling; it will be a finding worth getting excited over. It doesn’t even mean that it won’t be indicative of life; a world with oxygen and organic molecules may well be overflowing with living organisms. But it does mean that we have to be careful.

Historically, when we’ve looked to the skies for evidence of life beyond Earth, we’ve been biased by hope and what we know on Earth. Theories of dinosaurs on Venus or canals on Mars still linger in our memories, and we must be careful that extraterrestial oxygen signatures don’t lead us to falsely optimistic conclusions. We now know that both abiotic processes and life-dependent ones can create an oxygen-rich atmosphere.

The hard problem, then, will be disentangling the potential causes when we actually find our first oxygen-rich, Earth-like exoplanet. Our reward, if we’re successful, will be the knowledge of whether or not we’ve actually found life around another star.”

If you were looking for life around a planet orbiting another star, how would you do it? Your first inclination might be to look for something just like Earth: an Earth-mass planet with Earth’s size and Earth’s orbital parameters around a Sun-like star. You might then go a step further and try to examine its atmospheric contents. If you found a large amount of oxygen and organic molecules in the same atmosphere, you might conclude that you’d found it: a world beyond our Solar System that was inhabited. But that’s not necessarily the case! 

Out of Dr. Sarah Hörst’s lab comes a new finding: oxygen and organics can arise through abiotic processes on exoplanets. Oxygen may not mean life, after all.

What Was It Like When The First Habitable Planets Formed?

“The galactic center, however, is a relatively difficult place for a planet to be considered habitable beyond a reasonable doubt. Wherever you have stars continuously forming, you have a spectacular slew of cosmic fireworks. Gamma ray bursts, supernovae, black hole formation, quasars, and collapsing molecular clouds make for an environment that is, at best, precarious for life to arise and sustain in.

To have an environment where we can confidently state that life arises and maintains itself, we need for this process to come to an abrupt end. We need something to put a stop to star formation, which in turn puts the kibosh on the activity that is most threatening to habitability on a world. It’s why the earliest, most sustained habitable planets might not be in a galaxy like ours, but rather in a red-and-dead galaxy that ceased forming stars billions of years ago.”

The cosmic story that created the Universe as we know it had a lot of intricate and fascinating steps along the way. The stars needed to live and die to create heavy elements; enough elements needed to form to make life and rocky planets possible; and the Universe needed to quiet down enough in the richest, locations so that life could sustain and thrive. That last step takes surprisingly long relative to the first few! While rocky planets might come into being less than half-a-billion years after the Big Bang, and life might be able to arise in under a billion years, having the right combination of planets that are habitable and continuously hospitable to life might take up to two billion years, even in the most optimistic of circumstances.

Still, that’s 7 billion years faster than it took for Earth to form! What could life in the Universe that got such a head start on us look like? Consider the possibilities as you learn what it was like when the first habitable planets formed!

We Know Almost Nothing About Proxima b, The Closest Exoplanet To Earth

“In reality, we do not even know whether this planet is Earth-like or Neptune-like. The typical border between an Earth-like world, where you have a rocky surface with a thin atmosphere, and a Neptune-like world, where you have a large gas envelope surrounding your world, is about 2 Earth masses. Proxima b has a minimum mass of about 1.3 Earths, but that’s if the alignment is perfectly edge-on. Since there’s no transit, we know the alignment cannot be exactly perfect, but how imperfect is it? That’s gloriously unknown.

If the alignment is inclined at more than about 25° from our line-of-sight, it’s likely to be a gaseous world, not a rocky, Earth-like one. But at this point, without further information, we cannot know.”

Two years ago, some amazing news came in from the astronomical world: the closest star beyond our Sun, Proxima Centauri, has a planet orbiting it. Named Proxima b, it has an orbital period of 11.2 days around a star just 0.17% as luminous as our Sun. This places it into what we call the habitable zone, as it receives approximately 65% of the energy that Earth receives from the Sun. It also has a mass that’s touted as 1.3 times the mass of Earth, but that figure is very suspect. We can claim that as the minimum mass, but can do no better than that. As far as life, water, oceans, or even an atmosphere goes, we have no idea. It could be a completely airless, barren world, or could have a thick gas envelope like Neptune.

Without more and better data, we simply cannot know. We know very little about Proxima b. Here’s how you can separate scientific fact from mere speculation.

Ask Ethan: Would Life On Earth Be Possible If We Were Anyplace Else In The Galaxy?

“[W]hat would happen if our solar system had formed a little farther up the arm of the galaxy? What would happen if we were at the tip of the arm? What if, theoretically, instead of the humongous black hole in the center of our galaxy, our solar system was there? Would there be major climate difference[s]? Would we be able to survive?”

We can all agree that what’s happened here on Earth is something that’s extremely special in the Universe. Our planet has developed and sustained life on it for over four billion years, and that life continues to thrive even at present. Our planet has been fortunate enough to have stable enough conditions and mass extinction events that have never eliminated 100% of the life that exists on our world. But how ‘special’ does that make Earth, that this is our story? Do we need a large Moon? A solar system like ours? A star like our Sun? And do we need to be located at our present location in the galaxy, or would many places be just as good?

It’s a tough question to answer with certainty given the paltry evidence we have, but we can certainly examine these questions in-depth. Let’s do exactly that for this edition of Ask Ethan!

New Podcast: Humanity’s 3 Hopes For Alien Life

There are three very different ways humanity is searching for alien life beyond Earth. We can directly search the various planets and moons in our Solar System for past or present biological signatures simply by sending decontaminated probes, and looking for the evidence in situ. We can indirectly look at distant worlds around other stars, searching for the characteristic changes to the atmosphere and surface that life would bring. And, most optimistically, we can search for intelligent signatures created, perhaps willfully, by a technologically advanced alien species. These are our three hopes for finding alien life, and we’re actively pursuing all three.

Here’s how the different searches work, along with some speculation about what we’re likely to find, and what motivates us to look!

Humanity’s 3 Hopes For Finding Alien Life

“Although it’s just conjecture at this point, scientists speculate that life in the Universe is probably common, with the ingredients and opportunities for it to arise appearing practically everywhere. Life that thrives and sustains itself on a world, to the point where it can change its atmospheric and/or surface properties, may need to get lucky, and is likely more uncommon. Evolving to become complex, differentiated, multicellular creatures is likely even rarer. And as far as becoming what we would consider an intelligent, technologically advanced civilization, it could be so exceedingly remarkable that in all the Universe, it might just be us. Yet despite how different these outcomes are, we’re actively searching for all three types of life in very different ways. When the first sign of alien life finally is discovered, which one shall emerge victorious?

No matter which method pays dividends first, it will be among the greatest day in the history of life on Earth.”

There are three very different ways humanity is searching for alien life beyond Earth. We can directly search the various planets and moons in our Solar System for past or present biological signatures simply by sending decontaminated probes, and looking for the evidence in situ. We can indirectly look at distant worlds around other stars, searching for the characteristic changes to the atmosphere and surface that life would bring. And, most optimistically, we can search for intelligent signatures created, perhaps willfully, by a technologically advanced alien species.

These are our three hopes for finding alien life, and we’re actively pursuing all three. Which one, if any, do you think has the best chance of paying off?