Photo by: NASA/JPL


Is There Life on Venus? Something Smells Fishy…

Does the presence of a stinky gas mean there was once life on Venus?

September 14, 2020

Phosphine is one of the grossest chemicals out there. Not because of what it’s made of–one atoms of phosphorus and three atoms of hydrogen–but because it’s really, really stinky. It’s commonly associated with decaying organic matter, if you need a mental picture. It occurs naturally through a variety of processes, most notably as a byproduct of non-oxygen-using life. But since oxygen-using life is quite common on our planet, thankfully this stinky chemical is relatively rare.

Who Stank?

Phosphine or phosphane is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas and pnictogen hydride. 3d illustration


Phosphine or phosphane is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas and pnictogen hydride.

Photo by: ollaweila


Phosphine or phosphane is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas and pnictogen hydride.

Recently some astronomers have been raising a big stink (pun very much intended) about Earth’s sister planet, Venus. For those of you new to Venus: don’t go. It’s a nightmarish hellhole of a planet, choking on so much poisonous carbon dioxide that its surface pressure is over 90 times that of sea level. The temperatures at the surface are hot enough to melt lead. It rains sulfuric acid.

It’s nasty. And it just might–might – be a home for life.

A certain subgroup of astronomers known as astrobiologists (and yes, that’s a thing) are hunting for signs of life outside the Earth. One of the most promising ways is to look for (and this is a pretty awesome jargon word) biosignatures. These are signs of life in the form of chemicals that don’t normally come from chemical (i.e., boring unless you’re a chemist) processes.

An example of this is oxygen. The vast majority of the oxygen in our atmosphere comes as a byproduct of photosynthesis (in other words: life). If we were to find a lot of oxygen in another planet’s atmosphere, it just might be teeming with little critters.

Another potential biosignature is stinky molecule phosphine. Sure, it’s possible to create phosphine naturally, but it takes a lot of energy, and is very unstable–the UV radiation from the sun does a really good job at breaking it apart.

I’ll cut to the chase: a group of astronomers recently announced the presence of a load of phosphine in the atmosphere of Venus. A potential sign of life in basically the last place you would expect to find it.

Now we also see a lot of phosphine in the atmospheres of Jupiter and Saturn, and we really don’t think it comes from life on those giant planets–more likely it originates in some super-intense chemical process deep in their interiors.

But Venus?

Venus, computer artwork.


Venus, computer artwork.

Photo by: SCIEPRO


The astronomers argue that they’ve thought of every possible way to make lots of phosphine in Venus without involving life, and keep coming up short.

Where could life exist in that hellscape? Well, a few dozen miles up in the atmosphere is pretty clement: room temperatures and standard air pressures. The air is still full of noxious carbon dioxide and sulfuric acid, but hey life has found footholds in stranger places.

But still, as with all stories of this nature, I urge caution and skepticism. Venus is a strange, strange environment that we barely even pretend to understand. Lots of crazy chemistry could be going on. There have been hints of life on Mars for decades that have been undermined by further study, and the same is likely true for Venus. By the time the news excitement dies down, there is likely to be a dozen hypothetical processes proposed that could explain the strange presence of phosphine on Venus.

Which is exciting if you’re into cool, weird chemistry, but not so exciting if you’re into life.

Paul M. Sutter

Paul M. Sutter is an astrophysicist at Stony Brook University and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of How to Die in Space.

Next Up

Is Interstellar Travel Really Possible?

Listen folks, I love a good sci-fi movie as much as anyone. Cruising around the galaxy, finding weird stuff, and blowing up aliens--it’s all good. But just because a writer can come up with something, it doesn’t make it possible. I’m sorry to say that we’re going to be bound to our solar system for a really, really long time. As in, probably forever.

The Milky Way Broke its Arm (But is Totally Okay)

The Milky Way is a giant, magnificent, truly transcendently beautiful spiral arm galaxy. It’s too bad we can’t get a decent picture of it. The problem is that we live inside it, and so astronomers have to work extra-hard to construct an accurate map.

What Is a “Super Earth” and Why Do We Care?

Super Earths are super cool, and you should really know about them. In short, they are planets slightly bigger than the Earth (hence the name). And the cool part? They might be a home for life, and they’re way easier to study than regular Earths.

The Super Flower Blood Moon Total Lunar Eclipse is Tonight

Early in the morning of May 26 most of the world will be able to look up and see a total lunar eclipse of the Super Flower Blood Moon.

NASA is Going Back to Venus. Here’s Why You Should Care.

Recently NASA announced two brand-spanking new missions to our sister planet, Venus. This is the first time in over 40 years that Americans have led a mission to that enigmatic planet. What do they hope to find? Clues to our past…and answers to our future.

NASA's New Rocket is Taller than the Statue of Liberty

The massive space launch system was unveiled last week. Following successful completion of upcoming simulation tests, NASA will set a date for the first of the Artemis II lunar missions.

Who Wants to Be an Astronaut?

If you've ever wanted to travel into space, this is your chance. No, really. Even you.

Romeo and Juliet: The Story of Galaxy Collisions

Our Milky Way galaxy is on a collision course. With destiny. With destruction. With fate. With our nearest neighbor, Andromeda. You can stream HOW THE UNIVERSE WORKS on discovery+.

Want to See a Black Hole’s Magnetic Field? Now’s Your Chance

A couple years ago, the team of astronomers with the Event Horizon Telescope wowed the world by providing our first-ever snapshot of a real-life black hole. Now they’ve done one better and mapped out the swirling magnetic fields around the monster. It’s our first ever glimpse of the forces that power the largest engines in the universe.

Astronomers See Flashes from Behind a Black Hole

Want to see what’s behind a black hole? Easy. You just…stare at it. The whole thing is pretty weird to contemplate, but an excellent example of the space-bending (and mind-bending) powers of black holes.

Related To: