Jupiter, at first glance, is perhaps the last
place you would expect to find life. It's after all a roiling, hot gas giant. But it might surprise you that the gas giant
itself has, at least in the past, been considered a possible home for life. And not just microbial life, but complex life. And while it's a long shot, it's not ruled
out that something could inhabit the upper reaches of its atmosphere. Jupiter is a generally misunderstood world. It's usually thought of as a huge ball of
gas. But in reality, it's much more complicated
than that. If you descend into Jupiter's atmosphere,
you will first find a turbulent upper layer made up of a mix of gases, mostly hydrogen
and helium. The further you go down, the hotter it will
get due to the high pressures of the interior. At about 1000 kilometers below the top of
the cloud deck you transition to one of the stranger natural substances thought to exist
in our solar system. You would find metallic hydrogen. Under the extremely high pressures of Jupiter's
atmosphere hydrogen would be compressed into a soup of nuclei and electrons that exist
in an ambiguous state that wouldn't have a clear boundary between a gas and a liquid. While metallic hydrogen is described as a
liquid, it's a bit different than any other. It's better to think of the hydrogen as simply
getting denser the deeper you go rather than use labels. Beyond that thick layer at the heart of the
planet, it's thought you would find a core. Not a lot is known about this core, but it's
probably made of rock and metal just like the inner planets. It's not yet known if it's solid or completely
molten or some mix of the two. Planetary cores are generally hard to study,
and Jupiter's is among the hardest. But how could such an alien and strange environment
such as Jupiter support any kind of life? The answer is in the conditions of the upper
atmosphere. In 1976, Carl Sagan and Edwin Salpeter released
a paper, citation in the description below, in which they suggested that ammonia-based
life of some kind might exist in the atmosphere of Jupiter. They envisioned three hypothetical kinds of
animal that might live there which they termed sinkers, floaters and hunters. In particular, the floaters were envisioned
as enormous gas bags, perhaps kilometers across and visible from orbit that suspended themselves
in the atmosphere using helium. Now, we have never seen floaters with any
of our probes to Jupiter and this was a very speculative paper based on thinking deriving
from what we know about our own oceans and life there. No such indications have ever surfaced that
such a thing could really exist on Jupiter. But what does exist at Jupiter is the possibility
of some interesting life related chemistry. The chemicals in the upper atmosphere of Jupiter
do include water, ammonia and methane along with plenty of hydrogen in gas form. These just happen to be the gases used in
an interesting experiment done in 1952 by Stanley Miller and Harold Urey. They wanted to recreate the conditions of
early earth and see if they could produce the initial prebiotic chemical reactions that
are believed to have ultimately led to the dawn of life on earth. What they did was pass water vapor through
a mix of hydrogen, ammonia and methane gas. They then subjected that mix to periodic electrical
discharges intended to simulate lightning. Then they looked at what came out the other
side and it was, to say the least, interesting. They found lots of organic compounds coming
out of the mix. Most importantly, they initially found a number
of the amino acids that are used by life. In 2007, however, the original sealed samples
from the experiment were reexamined and as it turns out all 20 amino acids were present
that are used by life on earth. Since then, numerous revisions have been made
to the model of what our planet's early atmosphere was like. As a result, a number of subsequent experiments
have been done based on the Miller-Urey work ranging from changing the energy source to
a volcano rather than lightning, adding in new chemical mixes that more accurately resemble
what the early atmosphere is thought to have been like and so on. The results of many of these experiments has
been the creation of even more types of organic molecules than Miller and Urey's experiment
produced. These experiments make it seem likely that
at least the basic the chemistry for life first arose on some volcanic island on Earth
billions of years ago. For Jupiter, this would be a more difficult
process though it does have extremely powerful lightning and no shortage of heat. The problem is in its atmosphere, which is
extremely violent. Gases circulate on that world by rising in
certain areas and falling in others and any kind of life, microbial included, would have
to deal with impossibly high temperatures and pressures when circulating deep below. As Sagan noted in a segment on this topic
in his television series Cosmos, such organisms would have to reproduce very rapidly. And while the prospect of life living in the
atmosphere of Jupiter is somewhat of a stretch due to that roiling atmosphere, there may
be gas giants and even brown dwarves in the universe calm enough to harbor at least some
form of microbial life in their upper atmosphere, or possibly even more. In a paper by Jack Yates and his colleagues
at the University of Edinburgh from late 2016, link in the description below, they detail
a hypothetical way for brown dwarves to harbor some form of life. They note that the upper atmospheres of some
brown dwarves might harbor clement conditions with pressures and temperatures similar to
earth. Relying on updrafts, life might exist in this
zone within the brown dwarves. This opens up vast new territory in the search
for life in the universe. In 2013, a brown dwarf known as WISE 0855-0714
was discovered and seemingly has water-based clouds floating in its upper atmosphere. Using Sagan and Salpeter's research, they
applied that thinking to the brown dwarf and concluded that yes, life might exist there. The James Webb Space Telescope is slated to
take an in-depth look at close brown dwarves, such as WISE 0855-0714 which is only 7 light
years away. And while it's hard to envision native life
having a way to evolve in the first place in a place like Jupiter or a brown dwarf,
it's been suggested that dust floating in the atmosphere might do the trick for a solid
place to do it or even microbial life being delivered by an asteroid through panspermia. One can imagine that this kind of inhabited
gas planet might be quite rare, but it does seem to at least be hypothetically possible
and that in the future, when we do detect evidence of life, perhaps it might come from
the spectra of a brown dwarf's atmosphere. But I'm left with one lingering, highly speculative
thought after making this video. If Jupiter, then why not Saturn? Thanks for listening! I am futurist and science fiction author John
Michael Godier currently probably sounding a bit scratchy because it's spring and my
allergies are working overtime and be sure to check out my books at your favorite online
book retailer and subscribe to my channel for regular, in-depth explorations into the
interesting, weird and unknown aspects of this amazing universe in which we live.
