(soft ambient music)
- Deep within the acid clouds above Venus,
astronomers have detected something new,
a gas that could be a sign of life.
The gas is phosphine, a toxic molecule
with an odor of garlic and dead fish.
Astronomers discovered the compound in a cloud layer
where temperatures are fairly close
to those on earth's surface.
Phosphine is exciting because of where it comes from.
On earth, it's either manufactured by humans,
or it's a natural byproduct of life.
It just doesn't show up anywhere else,
and there's no human manufacturing on Venus.
Phosphine is not sure fireproof
there are alien microbes on the cloudy planet,
but it does mean that something is going on there.
Something that we don't understand.
Here's the backstory.
Late last year, a team at MIT put out a paper
calling phosphine gas a bio signature,
a substance that may come from life on another world.
The team argued that phosphine has no
abiotic false positives,
meaning nothing but life could naturally produce the gas
on a rocky planet like earth.
They suggested astronomers look for phosphine
in the atmospheres of planets orbiting distant stars.
Find phosphine and you've maybe found alien life.
But this year, an international team,
including several researchers at MIT,
started looking for phosphine a little closer to home ,
in the clouds above Venus.
They used two telescopes to break apart the light
filtering through gases in Venus's atmosphere.
By looking at various wavelengths or spectra,
as they pass through these molecules,
scientists can find fingerprints of the gasses present,
and amazingly they found it, a signature line
in the spectrum right where phosphine should be.
It's a pretty low concentration.
One of the researchers described it as "a few tablespoons
"in an Olympic-size swimming pool."
But that's actually quite a lot
compared to what we find on earth.
And that may mean that something
is actively replenishing the supply.
To stress test their find, the team tried to come up
with other explanations for the gas.
They modeled things like lightning strikes and meteors
to see if those events might produce
this amount of phosphine.
So far, nothing matches up.
Now, things could change in the months ahead.
It's possible that this signal could be explained
by another gas, sulfur dioxide.
We'll need more observations to confirm one gas or another.
And even if it is phosphine,
life may not be the best explanation.
Venetian clouds are a nightmarish place for life to survive.
The clouds themselves are made of droplets of sulfuric acid.
So acidic that they're literally off our pH scale.
Any life we're familiar with would face wrong odds there.
And for what it's worth,
there have been other alien false alarms before.
In 1996, researchers found what looked like
fossilized bacteria in a Martian meteorite.
Then president, Bill Clinton, even gave a speech about it.
- If this discovery is confirmed,
it will surely be one of the most stunning insights
into our universe that science has ever uncovered.
- Ultimately that claim did not hold up to scrutiny.
So the reaction among plenty of experts right now
is curiosity, but caution.
But if the evidence remains strong,
it would completely change our understanding
of what makes a planet habitable.
Today, we focus on planets that look a lot like our own,
but Venus may tell us we need to expand our search.
It would also raise Venus's clout as a place to visit.
Mars has gotten a lot more attention
over the past few decades,
but phosphine could inspire new micro punting missions
to the cloudy planet.
For now, this detection is just the beginning
of a long journey for astrobiologists.
There are no definitive answers
about the presence of phosphine or the way it's created,
or the question of whether or not
we're alone in the universe.
This is a big story that's sure to generate a lot of hype,
so be wary of any "Scientists Have Found Aliens on Venus"
type headlines.
Let us know in the comments which you've seen
and what you think of this story.
And thanks for watching.