(Cassini Imaging Team, SSI, JPL, ESA, NASA) The possibility of alien life thriving somewhere other than Earth is now stronger than ever before.

Underwater hydrothermal vents — the same kind that may have spawned life on our planet — seem to be lining the ocean floors of Saturn's tiny, water-rich moon called Enceladus, according to two recently published papers.

This is the most compelling evidence we have so far for the existence of these vents anywhere other than Earth. The latest discovery is a tantalizing hint that the conditions right for life may be present outside of Earth.

While Enceladus is watery, it is no Earth: It is only about 300 miles across. But under a thick, icy shell lies a water ocean habitat that resembles the conditions on an adolescent Earth, between 3.5 and 4 billion years ago.

Back then, Earth was covered in a single, global ocean. Most of the ocean is thought to have been extremely acidic — to0 acidic to create life — except around certain underwater, hydrothermal vents in which pockets of warm, less-acidic water could have formed. These conditions would have been the ideal place for life to arise on Earth, according to NASA scientist Michael Russell.

With this latest announcement, hydrothermal vents with these pockets of warm water are now believed to exist outside of Earth — at the bottom of Enceladus' oceans.

So how did these researchers find vents under miles of ice? Using the instruments on board the Cassini spacecraft, the team measured the size and number of silicon-rich particles, called silicates, in Saturn's second outer-most ring, the E ring. The E ring is made of particles that came from the moon's plumes and therefore tells scientists something about what is going on underneath the surface.

Once formed, these particles rise to the surface, where they escape to space through plumes off the moon's south polar region, shown in the arresting image below taken by Cassini:

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(Cassini Imaging Team, SSI, JPL, ESA, NASA) The silicates' chemical makeup, size, and abundance give an indication of what is forming in the ocean underneath Enceladus' surface. And the result is incredibly exciting.

To show that these particles could come from hydrothermal vents, the team re-created them in the lab. To their surprise, they discovered that particles of this chemical composition, size, and abundance grow only under a very specific set of conditions. The team reported their findings Wednesday in the journal Nature.

What's more shocking is that these conditions are remarkably similar to a unique, underwater environment here on Earth, called the Lost City, which some researchers consider the cradle of life.

A miraculous find

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(NOAA Photo Library on Flickr) Lost City Expedition 2005. One of four pinnacles that form the summit of the 200-foot tall carbonate chimney called Poseidon in the Lost City hydrothermal field. The Lost City is a field of hydrothermal vents that was first discovered in the mid-Atlantic ocean in the year 2000. Unlike other hydrothermal vents on Earth, this unique environment has basic, non-acidic waters that clock in at comfortable temperatures between 100 and 200 degrees Fahrenheit. Other vents can reach up to a scorching 860 degrees Fahrenheit.

Moreover, the life that thrives in the Lost City is mostly simple microorganisms — nothing like the larger, more complex life-forms hanging around other vents on Earth's ocean floor. Some scientists think these super-simple life-forms could be close-descendants of the first single-celled life on Earth.