Titan is Saturn’s largest moon, nearly the size of Mars, but it’s more than just a moon — it is a laboratory for life unlike anything we see on Earth. In a strange way, Titan may be the most Earth-like world out there. It is the only other place we know of that has liquid on its surface, but in Titan’s case the liquid is mostly methane, which fills up seas, flows in rivers, and even rains down from the sky. It’s so cold there that the mountains and valleys are sculpted from water ice as hard as stone.
But if humans were to journey to Titan, we wouldn’t need the bulky pressure suits that astronauts wear for spacewalks. That’s because, despite the moon’s weak gravity, the atmospheric pressure near its surface is about 60% higher than on Earth – it is the only moon in the solar system with a substantial atmosphere. The atmosphere is mostly made of nitrogen with a small amount of methane, but near the top of the atmosphere, high-energy particles and radiation from the sun split these atoms apart. Their constituent parts react with one another to form a thick orange haze.
Carbon-rich compounds called tholins snow down from the haze onto the moon’s surface, building up huge dune fields in the flatlands. These tholins could be the building blocks of life – if it is possible to base life on liquid methane and ethane instead of water. If there is any liquid water on Titan, it must be buried deep beneath the frigid surface, hidden in impact craters, or erupted by strange, icy volcanoes. Because the primary surface liquid there is methane, one might expect any life that evolved there to be methane-based just as Earth life is water-based.
It’s not clear that Titan could host any living organisms, but the liquid on its surface makes it one of the most promising places in the solar system to look. If there are signs of life there, it could be the key to understanding what ingredients are necessary for life to evolve and how it arose on Earth. It could tell us whether we should expect any life we find anywhere in the cosmos to be Earth-like, or we should discard all expectations and be open to the possibility of life vastly different from anything we’ve seen before. Continue reading from The Planetary Society
Our solar system formed about 4.5 billion years ago from a dense cloud of interstellar gas and dust. The cloud collapsed, possibly due to the shockwave of a nearby exploding star, called a supernova. When this dust cloud collapsed, it formed a solar nebula—a spinning, swirling disk of material.
At the center, gravity pulled more and more material in. Eventually the pressure in the core was so great that hydrogen atoms began to combine and form helium, releasing a tremendous amount of energy. With that, our Sun was born, and it eventually amassed more than 99 percent of the available matter. Continue reading from NASA
