On this channel we often wander the universe
distantly, at least with our imaginations if not physically going there. But this time, let’s look closer to home,
but not too close. It’s somewhere we’ve actually visited
in person. It’s the moon, and like most objects in
the universe, it is no stranger to mysteries and oddness. So here are 10 strange aspects of our own
moon. Number 10. Human Impact On the Moon Will Last A Very
Long Time We live on a very, very dynamic planet. The forces of nature on earth are constantly
at work reshaping our world. Rocks weather, volcanoes deposit new rock,
the winds and water erode. Not so on the moon, where erosion, provided
by micrometeoroids impacting the surface over immense amounts of time and to some degree
the solar wind, is so slow that any change introduced by human activity will last almost
indefinitely. Take this footprint from the Apollo missions. It’s estimated that it could last at least
several million years at current rates of erosion, but the equipment itself such as
the descent stage could last 100 million years. That’s if a bigger meteorite doesn’t come
along and entirely obliterate a landing site. But there is one type of object left on the
moon that almost certainly is no longer there. It’s the American flags. Due to the intense ultraviolet radiation from
the sun, earth has some protection there, and things still fade and degrade, the moon
has no protection at all and the nylon flags would have completely degraded and disintegrated
over the decades. By now, nothing likely remains other than
the poles. Number 9. The Moon … has a smell During the Apollo missions to the moon, it
was noted by the astronauts that the moon’s dust was not easy stuff to deal with. No matter how well they tried to brush off
their suits before going back into the lander, they could not eliminate the lunar dust that
clung to them. Upon getting back into the lander and taking
off their helmets, they noticed that the lunar dust smelled very strongly. Described as smelling something like spent
gunpowder, the reason for this smell remains a mystery because gunpowder and lunar dust
have very different compositions. Ideas include ions from the solar wind, along
with the very dry lunar dust coming into contact with humidity creating the odor. Presumably, this will be an issue for any
lunar colony we found, and I would imagine good air filtration will be a must. But there’s another aspect to this, astronaut
Jack Schmitt even had some kind of allergic reaction to the dust the first time he smelled
it, though he later acclimated in later incidents. Number 8. The Moon May Have Water … and Sparks The lunar surface is a very, very dry place. Desert doesn’t describe how dry it actually
is. Water does not survive on the surface long
term due to the action of the intense sunlight. But, there are areas on the moon where sunlight
never reaches. In the 1960’s it was first conjectured that
certain craters on the moon, near the poles, that were deep enough to never receive any
sunlight and thus could still contain water ice, deposited there long ago by comets. Evidence mounts that this is indeed the case,
with NASA’s Lunar reconaissance orbiter discovering that the floor of Shackleton Crater
near the Moon’s south pole could have as much as 22 percent of its surface covered
in ice. This is important for any hopes of founding
a human colony on the moon. Water is heavy, and launching it from Earth
is expensive, so having as much water natively available to a colony is a great thing, not
only for drinking and growing food, but also making oxygen and fuel. That’s one less problem facing those with
the intent of colonizing the moon. But that’s not the only thing to be found
in the permanently shadowed regions of the moon. Scientists have found that the soil in these
regions shows evidence that it has been partially melted. That’s not too surprising for a surface
being bombarded by micrometeoroids, but there may be something else going on here melting
the soil. A recent NASA study found that during powerful
solar storms, the moon’s surface might become electrically charged in the very cold permanently
shadowed polar regions. That charge would build up over time, and
then discharge causing the soil to literally spark, and slightly melt. Imagine how alien that might seem, walking
on the lunar surface in pitch black conditions, the only sources of light being the stars
blazing overhead with no atmosphere or light pollution to mute them, and tiny flashes from
the sparking soil beneath your feet. Number 7. The Moon May Have Once been Part of Earth A great mystery within planetary science is
just how the moon formed. The best explanation yet, though not universally
accepted in the scientific community, is that early in the earth’s history, so early it’s
best to call it proto-earth at that point, a Mars sized objected impacted proto-earth
and blew out the materials that would become the moon into space. Given the name Theia, this Mars sized object
is thought to have been a glancing blow where it hit at a certain angle sufficient to toss
enough material out of the collision that could coalesce and become the moon. This is backed up with chemical similarities
between the moon and earth’s geology, which is not consistent with objects that formed
in different areas of the solar nebula. But this creates a problem. The moon is responsible for earth’s tides. That in turn is suspected to have played a
role in the genesis of life on earth, tidal pools are a possibility for the solvent where
the chemistry of life first occured. So if the moon hadn’t existed, then tidal
pools couldn’t have occured as described. So are we here because of the existence of
the moon? And, does that apply to the rest of the universe? If terrestrial planets like Earth do not have
moons can they host life? Unknown. But if that’s the case and the natural chemical
laboritory for the genesis of life relies on the existence of a terrestrial planet with
a large moon, then how often does that happen? We don’t know, but Mars only has tiny inconsequential
moons, and Mercury’s got nothing, and Venus, which is effectively earth’s twin doesn’t
have anything … does this mean that terrestrial planets within the inner parts of star systems
don’t form moons unless an accident happens like the glancing blow? We do not yet know the answer to the question. But it could solve the Fermi Paradox in coming
years as we figure out what the deal is with earth-like planets and exomoons. Number 6. Moonquakes We always think of the moon’s tidal effects
on earth as a phenomenon of our ocean that’s caused by the moon, but only affects us. But it’s very much a two way street, earth
too has tidal effects on the moon, and it causes one major effect. Moonquakes. During the Apollo missions the astronauts
set up seismometers on the moon. This was essentially to see if there was anything
happening, but expectations of the time were that they might not pick anything up and moonquakes
do not regularly occur. This is because the moon does not have plate
tectonics, which is one of the main driving forces behind earthquakes on earth. But the seismometers did pick up moonquakes,
and there were several different types. One obvious cause were those created by meteorite
impacts. Another type were thermal in nature, as the
crust of the moon contracts and expands when sunlight is either present or isn’t, then
small quakes occur. But very deep quakes were also found, as much
as 700 kilometers below the surface. These appear to be created by earth’s tidal
forces acting on the moon, as our planet pulls on the moon, it has to adjust and when it
does it creates a moonquake. These quakes are significantly weaker than
what we experience on earth but the final type detected by the Apollo missions is a
bit more mysterious in origin, and a bit more powerful. These were shallow moonquakes. The cause of these more powerful moonquakes
is still a mystery, but it may involve movement in fracture zones in the rock underlying the
surface of the moon. Only more study, and more seismometers on
the moon will shed light on these more powerful earthquakes. Number 5. Why is the far side of the moon so different
from the face we see? The moon is tidally locked to earth and always
presents the same face to us, in fact, until 1959 when the soviets sent a probe, no human
had ever seen the far side of the moon. Before then it had been expected that we could
reasonably assume that the far side would look much like the part we see. This was most certainly not the case. The near side of the moon is covered in dark
regions, the familiar lunar maria that we look up at in the night sky. The far side is nearly devoid of these, instead
showing a dramatically mountainous and cratered surface. And it’s not just visually different. It’s been found that the moon’s crust
on the far side is apparently significantly thicker than the near side. The reason for this is not known, but it does
explain the differences between the near and far side. The thinner side was simply more prone to
allow for molten mantle material from the moon to flow out after an impact, forming
the maria. But it doesn’t answer the question as to
why the far side’s crust is so thick. One possibility is that when the moon formed
after the collision with theia, the coalescing material may have formed two moons, a large
one and a small one in a similar orbit. At some point they collided, but not in a
huge explosive event, but rather something like a slow splash, where the object basically
flowed out onto the far side of the moon, causing the thicker crust on one side. But, there’s a problem. If this is what happened, we would expect
to find differences in composition on either side of the moon. We don’t, the variations within the composition
of the lunar surface appear continuous between both sides. A second idea is particularly interesting
to imagine. After the formation of the moon after the
impact with Theia, the moon would have been seriously close, as close as 20,000 kilometers. And both earth and the moon would have been
in a molten or semi-molten state at this time. Given how close they were, the tidal effects
on both bodies would have been severe. During this time, the tidal locking of the
moon might have occurred, with the near side facing a very hot earth, and the far side
cooling faster. This could have allowed vaporized materials
migrate to the cooler far side of the moon, and condense and build up, building up a thicker
crust over time. 4. The Moon is Receding into Space While the moon was once closer to earth, the
process of it receding has never stopped and each year the moon moves about 4 centimeters
further away. This leads to an odd coincidence, that the
moon’s apparent size in the sky is nearly identical to the sun, it allows for total
solar eclipses and a nearly complete view of the sun’s corona. This is rare, while eclipsing bodies in the
solar system aren’t rare, it is rare that our moon can so exactly block the sun’s
disk. This was not always so, and in 600 million
years, it won’t be possible and only annular eclipses will be visible from earth. As the moon moves further away, things are
eventually going to get chaotic here on earth. Sometime around 3 billion years from now,
it will so distant that it no longer regulates earth’s rotation. This means that earth will undergo serious
changes in its axial tilt, and the whole thing will become highly irregular. But, at least it’s better than what’s
going to happen with Mars. It’s moon Phobos is set to collide with
Mars in only about 50 million years. It’s too small to destroy Mars, but if we
have colonies there at that time, it’ll be a problem to tackle for sure. 3. Without the Moon, we May Never have Evolved One of the biggest questions within the subject
of the origin of life on earth is the role of the moon. One possibility is that life first arose here
in oceanic tidal pools. Water accumulates in a pool, essentially becomes
stagnant, and that allows for the chemistry of the beginnings of life might occur. If this is the case, then the moon causes
the tides, and without it, life on earth might not have been able to arise. While speculative, the actual conditions for
which life to come from abiotic chemistry are poorly understood at best, and there are
other ways for water to pool than tides, it does raise an interesting possibility. If indeed a large moon around a terrestrial
planet is required for life to arise, then look at the inner solar system. Venus has no moon, and Mars just has very
tiny ones. It would mean that they had no chance for
life. And Earth only had it because of a chance
collision with a Mars sized object. Therein is a question, do large moons indeed
form around terrestrial planets in most circumstances? We’ve never seen that with exoplanets, small
planets like earth are very difficult to detect, and even smaller moons around them, even less
so. So it may be that we live in a very unusual
system. The Earth-moon arrangement may be quite rare
in the universe, and if it turns out that this arrangement is a requirement for life
to arise, then we live in a very lifeless universe. But, again, that’s speculation. We don’t know. But it’s certainly ominous as far as life
in the universe goes. 2. The End of the Moon The slow estrangement from the moon as it
spirals out has a happy ending of sorts. The moon’s attempted escape faces an insurmountable
problem. That is the sun’s evolution to become a
red giant. As it does so in the far future, at some point
during the expansion, the gases from the sun will cause drag on the moon, and cause it
to start falling in towards earth again. As it approaches closer, it will hit the Roche
limit, which means that the gravitational forces holding the moon together will be overcome
by tidal forces from Earth. This means that the moon will predecease earth,
and be torn apart to form a ring system. The dying Earth, for a time, will resemble
Saturn as it is today. But not for long. This ring will fall to earth, and then the
earth itself will be consumed by the sun. And that will be it. Or will it? Other models suggest that the moon might actually
be tossed away from earth, with earth being destroyed, and then spend it’s lonely eternity
without its former companion. Or it could be that the earth and moon system
isn’t consumed at all, the process of a star losing mass as it swells to a red giant
stage isn’t well understood, so it might be that the scorched earth and moon will still
spend eternity together, much as they are now, orbiting, in a probably very changed
way, a cooling white dwarf cinder remnant of the sun. Number 1.The Moon Is Being Bombarded By Life Orbiting a planet with an enormous biosphere
and even a civilization living on it is going to expose a moon to life, in a number of different
ways. Most obviously is when that civilization lands
on its surface and plants a flag on it. But that’s not the only way life from earth
could end up on the moon. Now, ending up on the moon and living on it
are two different things, the moon is far to harsh for anything to survive there for
long. But, just as meteorites of lunar origin are
found here on earth, it may also be the case that rocks from earth have transported life
to the moon through panspermia. It’s safe to say that life didn’t last
long, but it’s possible that even tardigrades, which are not microbial, might have made it
to the moon in some form, and of course travelling with Apollo would have been bacteria, and
even within the astronauts themselves in their intestinal tracts. But humans aren’t the only macroscopic life
from earth to have been to the moon, there is another seemingly unlikely visitor to the
moon that greatly outnumbers the number of humans that have visited the moon. And, if you know where to find one, you can
meet one of these alternative astronauts yourself, and even talk to it for hours if you’re
so inclined. It’s a group of trees. During the Apollo 14 mission astronaut Stuart
Roosa used his small amount of space allotted to carry personal items to carry tree seeds. Roosa had once been involved with the US forest
service in suppressing wildfires, and wanted to pay tribute to the US Forest Service. What better way than to bring along some seeds. And, there was science to this. Scientists used the opportunity to see what
would happen to the seeds after being on the moon. Turns out, the seeds were resilient, and most
of them germinated. And the seedlings were distributed. And cuttings were made and distributed, meaning
that there are a lot of moon trees out there. Unfortunately, the record keeping was poor
so for the most part we don’t actually know where most of the moon trees are currently
located. Efforts are ongoing to find the moon trees. Many of them have plaques from when the trees
were distributed in the 1970’s, but some of them will never be known and could be anywhere. Known examples are growing at Goddard Space
Flight Center, a Girl Scout camp in Indiana, (find more). And, trees generally are long lived. For example, some of the redwood trees from
the experiment could live for centuries. Perhaps their seeds will be brought back to
the moon in a new round of exploration. Thanks for listening! I am science fiction author and futurist John
Michael Godier currently angry at the garden weeds. They’re everywhere and we wouldn’t have
this problem if we’d never developed agriculture. Technology. So I’m currently living primitively. Yesterday I painted a picture of an antelope
on a cave wall, and today I’m grinding up cornmeal, but I’m not using rocks. I’m using old cell phones. And it’s not working out well. Primitive sucks! O’neill cylinder time! And now I’m going to the grocery store 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.
