Titan: All the coolest facts about Saturn's largest moon

Saturn's moon Titan is one of the most unique bodies in the solar system and shares some incredibly important features with Earth itself.
John Loeffler
Saturn's moon Titan.
Saturn's moon Titan.

NASA 

In 2019, NASA announced that it would be sending the Dragonfly mission to Saturn's moon Titan, raising the profile of one of the hundreds of moons in our solar system to new heights.

It's easy to see why when you dig into it. Titan is the second largest moon in the solar system, after Jupiter's Ganymede, but even though its sheer size makes it worth studying, there are a number of other amazing facts about Titan that make it easy to see why NASA is so interested in visiting it.

In many ways, Titan is a lot like Earth, while in other ways, it is dramatically different. All the while, it remains one of the best candidates for life in the solar system outside of our own planet, despite what might initially look like an inhospitable world nearly a billion miles away.

Titan is home to the building blocks of life

The first, and maybe most important, fact to know about Saturn's moon Titan is that it is literally awash in hydrocarbons. These hydrogen-carbon molecules form the essential building blocks of the amino acids and proteins that eventually gave rise to life here on Earth.

The most prominent of these is methane, which is considered an important marker for organic life, seeing as it is the byproduct of so many biological processes of life on Earth. This methane isn't the kind of gaseous methane we're used to here on Earth, however.

Titan is covered in standing lakes of methane and ethane

Titan: All the coolest facts about Saturn's largest moon
Artist's concept of Titan's rimmed lakes.

Titan is the only known world in the solar system other than ours to have standing pools of liquid on its surface, though in this case, it isn't water but a mix of methane and ethane.

These compounds are never naturally liquified on Earth's surface since methane's boiling point is a frigid -258.9°F (-161.6°C), which is substantially lower than the lowest temperature ever recorded on Earth, -128.6°F (-89.2°C) at Vostok Station, Antarctica, in 1983. Ethane's boiling point is just under that at -127.4°F (-88.5°C), so even at our coldest, Earth only just barely gets cold enough for liquid ethane to start condensing, only to boil off again with the slightest uptick in temperature.

The surface of Titan is much colder than even the coldest points of the Earth's surface, with an average temperature of -290°F (-179°C), according to NASA. Because of this, methane and ethane play the role of water on Titan, while water ice plays a similar role on Titan as rock does here on Earth.

Titan is nearly twice the size of the Moon and is bigger than Mercury

Titan isn't the largest moon in the solar system, but it just barely comes in second. With a radius of about 1,600 miles (2,575 kilometers), it is just two percent smaller than Ganymede but almost 50 percent wider than our own moon, and it's even bigger than the smallest planet in the solar system, Mercury.

Titan is the only other body in the solar system with an active water cycle

Titan's temperature is such that methane and ethane can evaporate from the lakes and rivers on its surface into the atmosphere. While in the atmosphere, it can condense again into a liquid and fall back to the surface as rain, creating the source of the rivers that flow into Titan's surface lakes.

These running rivers of hydrocarbons also carve channels into the water ice and surface material on the planet, giving rise to deltas, river basins, and other surface features similar to those we're used to seeing on Earth.

Titan's atmosphere is denser than Earth's

Titan: All the coolest facts about Saturn's largest moon
A view of Titan's atmosphere at moonrise.

Titan is also unique in the solar system in that it has an atmosphere thicker than our own, the only moon to claim such a feature. The atmosphere is mostly nitrogen (about 95 percent), with almost all of the remaining five percent being methane. There are traces of other carbon-rich compounds in the atmosphere as well.

The atmosphere of Titan is much denser than that of Earth, with about 60 percent greater atmospheric pressure on the surface. This is the equivalent of the pressure you'd feel swimming roughly 50 feet below the surface of an ocean or lake on Earth.

Titan isn't as massive as Earth, though, so it has a weaker gravitational pull on its atmosphere, meaning its atmosphere extends about ten times farther out into space than our own.

Titan likely has an ocean of liquid water beneath its surface

In 2005, the European Space Agency's Huygens probe measured the surface of Titan and determined that there is likely an ocean of salty, liquid water between 35 and 50 miles beneath the surface of Titan. This immediately made it a candidate for hosting alien life.

Though this ocean hasn't been confirmed, other observations of the moon give this possibility more support.

Titan might have volcanoes made of ice

If there is an ocean of liquid water beneath the surface of Titan, it's very likely that there are water volcanoes made of ice on its surface, with liquid water acting very much the way molten lava would here on Earth.

Humans could fly under their own power on Titan

Titan: All the coolest facts about Saturn's largest moon
NASA Dragonfly drones will explore the surface of Titan starting in 2034.

One of the things that have always eluded human beings is the ability to fly. Of course, we have airplanes, helicopters, and even rockets, but that's kind of cheating, in a way. When ancients wrote myths about flying too close to the sun with wings stitched together with wax, they envisioned us, individually, flapping our arms like birds and taking flight.

According to Amanda Hendrix, a senior scientist at the Planetary Science Institute, such a thing would be possible on Titan. We'd need a pair of fake wings attached to our arms, of course, since our arms aren't cut out for flying on their own, but with an atmosphere as thick as Titan's, human muscle power would likely be enough for us to take flight on the surface.

Titan is one of the few worlds where humans would be protected from the Sun

One of the biggest problems with space travel is that once you leave low-Earth orbit, you also leave the Earth's protective magnetic field and are exposed to the full brunt of solar radiation, which is more than enough to cause serious cancers and other physical issues.

NASA's upper-risk limit for exposure to solar radiation outside of low Earth orbit is just 200 days, which isn't a very long time when talking about long-distance space travel and habitation.

On Titan, though, the atmosphere is five times as thick as Earth's atmosphere, so harmful solar radiation is simply absorbed by the Titanic air, Hendrix says.

Other than the gas giants, the only other world with an atmosphere thick enough to protect humans from harmful radiation is Venus, and the scorching surface temperatures there are even more challenging than the extreme cold of Titan's surface.

While living on Titan might be a long way away, if it's ever even possible, we're set to learn a whole lot more in the next decade when NASA's Dragonfly mission touches down on the moon in 2034.

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