Something weird is happening on the planet Venus. We know that Venus is the
most earthlike planet in the Solar System, practically our twin sibling, So in
theory this place should be very familiar to us. But in reality, Venus
is so incomprehensibly strange that we still understand very little about the true nature of
this planet. So are we looking at a vision of the future, the
nightmarish end that awaits all planets, or is Venus a memory of our past,
of a time when the Earth itself was a young, hot volcanic wasteland.
The real secrets lie beneath the surface and above the clouds. This is
the mystery of the planet Venus. We know that there are many similarities between
Venus and the Earth. Both planets are very similar in size and mass,
they have the same rocky composition, They orbit in a relatively similar proximity to
the Sun. But one of these stranger similarities between the two planets is that
both both Venus and the Earth have a young, rejuvenated surface. So what
do we mean by that? Well, if you look at the surface of
Mars Mercury or Earth's moon, you'll find a dense pattern of impact craters.
These are the remnants of multi billion year old asteroid impacts that occurred when the
Solar System was young and still full of rocky leftovers from the formation of planets
and moons. The Earth was not spared from this ancient bombardment. Our surface
would just be as pockmarked as the Moon if not for the continuous rejuvenation of
plate tectonics. The Earth is constantly recycling mass from the surface down into the
mantle and creating new land through volcanic eruptions. The surface of Venus appears to
tell a similar story. The ancient battle scars have been wiped away, leaving
the age old Venusian surface at somewhere between three hundred million and one billion years
old. Except Venus does not have plate tectonics. Instead, it has one
continuous and stagnant lid of rock that surrounds the entire globe. So there's no
easy explanation as to how the entire planet has been resurfaced in such a relatively
small amount of time. Even one billion years on the cosmic scale is fairly
young. You don't need tectonic plates to have volcanic activity, and this is
how we identify that Venus has a stagnant lid. For a surface. On
the Earth, active volcanoes are concentrated along the borders between the tectonic plates,
while on Venus there are thousands of volcanoes spread out across the surface in a
seemingly random distribution. This would indicate that volcanoes simply spring up at any location
where the surface crust is thin, and that their formation is not driven by
physical movement. We have evidence that volcanic activity on Venus continues to the present
day, but this still doesn't fully explain the re surfacing event. Planets with
a stagnant lid will have lower overall volcanic activity than similar planets with tectonic plates.
On the Earth, volcanoes sweep back and forth across the surface over millions
of years, violently reshaping the land as they go, while on a planet
like Mars, volcanoes just sit in the same place for millions of years,
slowly and steadily erupting until they form gigantic mountains like Olympus Monds, the highest
peak in the Solar System. Actually, most of the highest mountains in the
Solar System are located on Mars. Thanks to its stagnant lid and stationary volcanoes.
You would think that a similar thing would happen on Venus, but that's
not been the case. It does have a couple of very tall mountains,
but overall the surface of Venus is much closer to Earth than it is to
Mars, which still leaves us wondering just what the hell happened here. One
of the more interesting theories about the resurfacing of Venus is that it all happened
fairly abruptly in an explosive global cataclysmic event. The idea is that the stagnant
lid of the Venusian surface probably traps in a lot of pressure underneath the surface,
and since Venus is pretty close to the Sun, much closer than Mars,
there is the likelihood that a lot of thermal energy could build up inside
the planet over hundreds of millions of years, and eventually this pressure is going
to reach a point where it can't be contained any longer, releasing as one
catastrophic global volcanic eruption. If Venus did burst like an overfilled balloon at some
point within the past billion years, this would explain everything that we see on
the planet today. After the volcanic pressure release, the planet would cool back
down into a freshly resurfaced globe. Unfortunately, this cataclysmic event permanently erased any
surface evidence of the ancient past on Venus. When we look at the planet
Mars, we know that there was a time when liquid water flowed over the
surface in ancient rivers, lakes, and even oceans. If a relatively small
and cold planet like Mars could support the necessities of life, then it stands
to reason that Venus probably could have done the same. In order to find
the proof, we need to move up. We know that the atmosphere on
Venus is incredibly hostile. We know that is caused by a runaway greenhouse effect,
but we're not entirely sure how it got that way. To begin with,
the surface pressure of Venus is ninety two bar. That means the air
is ninety two times more dense than what we find at the surface of the
Earth. The majority of the Earth's atmosphere is actually composed of nitrogen, one
of the most common elements in the known universe. It accounts for around seventy
eight percent of the air. Oxygen is only around twenty one percent, and
the remaining one percent is mostly an inert noble gas called argone, and zero
point four percent of the Earth's atmosphere is occupied by greenhouse gases like carbon dioxide,
methane, and ozone. Interestingly enough, we know that Venus has around
the same massive nitrogen in the atmosphere as Earth does, and there are even
detectable amounts of molecular oxygen on Venus, but that is all dwarfed by an
unfathomable amount of carbon dioxide. In the Venusian atmosphere, it makes up over
ninety six percent of the total composition and at ninety two bar of density,
that is a lot of carbon dioxide. But where does it all come from?
The Earth manages its own carbon dioxide through a natural cycle. CO two
is absorbed by plants, they die, they fossilize, and then plate tectonics
eventually pull the fossils down deep into the mantle. Then humans came along and
started burning the fossils and putting them straight back into the atmosphere. But that
likely wasn't the case on Venus, and it's also not likely that Venus just
happens to have a massive amount of excess CO two that the Earth does not.
As far as we can tell Venus and the Earth started out as nearly
identical balls of molten rock. The chemical composition should be more or less the
same, meaning that some kind of natural force moved all of the excess carbon
from the inside of the planet to the outside and created the runaway greenhouse effect
that has superheated the planet's surface. This could have happened during the planet wide
cataclysm. That would be a reasonable explanation, meaning that Venus hasn't actually been
what it is now for all that long. Venus is closer to the Sun
than the Earth, but only by around thirty percent, which is not enough
to cause a huge difference in temperature. If you take the excess atmosphere out
of the equation, the average surface temperature of Venus would be around seventy degrees
celsius, which is still too hot, but it's as close to Earth temperature
as we would ever find anywhere in the Solar System. In fact, it's
very likely that there was a time when the atmospheric conditions of Venus were very
similar to the Earth, complete with large amounts of liquid water. Now,
like we said earlier, any geological evidence of flowing water is long gone from
the surface of venus, but the chemical evidence does remain. This comes in
the form of an atom called deuterium. Okay, stick with me here.
Deuterium is an isotope of hydrogen, which basically means that deuterium is a unique
variant of hydrogen that is created by the addition of a neutron inside the core
of the atom. Typical hydrogen only has one proton in the nucleus, while
deuterium has a proton and a neutron inside the nucleus. This gives utium a
heavier atomic weight than hydrogen, and on Earth there is typically one deuterium isotope
for every six thousand, four hundred and twenty atoms of hydrogen. Here's the
payoff. The concentration of deuterium atoms on venus is significantly higher, meaning that
at some point there was a massive amount of hydrogen that dissipated into space and
left behind its heavier isotope variance. This is a smoking gun indicator of a
water boil off event. The water boiled into steam, and the lightest hydrogen
atoms in that steam floated all the way up into the atmosphere and were carried
away by the solar wind, while the heavier atoms remained trapped somewhere in between.
So in this way, when we look at Venus, we are seeing
a likely future for the Earth. We often use Mars as an example of
a dead planet because its geological activity has ground to a halt, the atmosphere
has dissipated, and the average surface temperature has dropped below freezing. But this
is more like a planetary coma death is still to come. We live next
to a gigantic nuclear fusion reactor that is gradually increasing in power right up until
the hydrogen fuel source is depleted. Our Sun won't explode when it dies,
but it will expand outward to become a red giant, which will then eject
its corona and collapse into a white dwarf star surrounded by a nebula of matter
that used to be our solar system. Long story short, In the end,
everything burns. The Earth will not go quietly into that good night anyway,
nihilism aside. Our own planet will gradually, over billions of years,
start to look a lot more like Venus, so we can kind of reverse
engineer the process. It's likely that the water boil off comes first. The
Earth's magnetic field won't last forever. We're not sure if Venus ever had a
magnetosphere or if it just dissipated very early on, which would explain the planet's
short lifespan. Loss of the magnetic field allows the atmosphere to thin, end
hydrogen to escape. Lower atmospheric pressure, combined with a hotter sun, means
that water evaporates much faster and fails to recondense into rain. With no water,
the surface of the Earth gets dry and stiff, which is probably what
brings an end to plate tectonics and causes the outer trust to solidify into a
stagnant lid. Now, thermal energy builds up under the sealed crust of the
Earth until it pops like a balloon, and the entire surface is engulfed in
volcanic activity, spewing massive amounts of heavy carbon gas into the atmosphere to form
dense clouds that cling to the planet. And just like that, the Earth
five billion years in the future would be largely indistinguishable from the planet Venus as
we see it today, unless through reverse engineering Venus' demise, we can somehow
figure out how to stop our planet from sharing the same fate.