Not necessarily intelligent either. Doug Vakoch. President of METI International, which focuses on seeking out radio signals from intelligent extraterrestrial life. Obviously, we have yet to find life outside Earth. But if we did, what might it be similar to Tardigrades WhalesEvolution relies heavily on chance events, so theres no reason to expect that the history of life as weve seen it on Earth would play out the same on other planets. And yet, we see cases on our own world in which similar environments seem to pull for creatures that are built the same. Sharks and dolphins have similar body forms, though they are far distant relatives, one being a fish and the other a mammal. We should not be surprised to see a similar convergence of body shape when we encounter life on other worlds. But the particular combination of details that define each species on Earth could result in a suite of creatures that vary radically from planet to planet. The bottom line is that we should not expect to see a duplicate of Homo sapiens as we look for life beyond Earth. If we find life on the ocean worlds within our own solar system, how might it present itself How could it survive As we continue to explore our own solar system with robotic missions, we will be searching for signs of life indigenous to other planets and moons. Perhaps under the icy crust of Saturns moon Enceladus we will someday find evidence of microbial life, living off the energy provided by hydrothermal vents. But the waters of Enceladus are so bone chillingly cold that it would be hard to any imagine life there being much bigger than a bacterium. Might we find life on another moon of Saturn Titan is an intriguing possibility, with an atmosphere much denser than that of other moons, including carbon containing molecules. The apparent lack of liquid water on its surface is a strike against Titan for habitability, but pools of liquid ethane and methane may provide a critical crucible for life. Given that Titan is much further from the Sun than is Earth, its surface temperature is also much lower. Europas potential habitability hinges on the fact that its subsurface ocean shows signs of liquid water in direct contact with the moons mineral rich mantle. Another factor in favor of Europa as an abode of life is that it seems to be generating energy from within, which could support the metabolic processes of life. Although some of this internal energy may arise from radioactive decay, even more energy is likely to come from tidal flexing. All of these are promising signs, but is it sufficient to yield something like a tardigrade on Europa Lets be cautious, remembering that even on Earth, tardigrades are able to survive at the coldest temperatures and the greatest pressures for only a short time. As we seek out multicellular life on other worlds, it would need to be like a tardigrade on steroids, not only surviving a harsh environment for limited time, but being a true extremophile, thriving under conditions that are inconceivable for human beings. Are the gray aliens from pop culture a pretty unlikely representation of what intelligent life would look like How likely are any intelligent beings on other worlds to look like the gray aliens from pop cultureNot very. To find a humanoid form on another world, a whole series of unexpected events would have to been replicated. Early hominids adapted to a particular niche on the savannas of Africa, their upright posture letting them see stronger, fiercer predators at a distance. Under a different environment, having a brain at the top of the body might be a liability, with increased risk of damage by falling but with no great advantage to compensate. We see varied forms of intelligence on our own world. Octopuses are remarkably intelligent, but without controlling everything from a centralized brain. Instead, their smarts are largely distributed throughout their eight limbs. If we do make contact with intelligence on another planet, it means they have created radio or laser transmitters to signal us across the vast distances between the stars. But whether they did that with a pair of hands or a set of tentacles, we have no way of anticipating. Rocco Manicelli. Astrobiologist at NASAIf we do find life outside Earthlets say on a planet like Enceladushow big or small would it probably be I doubt that it would more than a single cell life form so the size would be comparable to a bacterium. The environment of Enceladus does not lend itself to support multi cellularity, in my opinion. What do you think is the biggest misconception about finding life outside Earth That if a planet or moon is in the habitable zone around a star then it has what it takes for life. That is not true, especially if you go back to Jim Kastings papers where he defines the habitable zone all it is is the zone where if water exists on a planet or moon that the water could be in a liquid state. That, however, is far from what it takes for life to originate and evolve. You need all of the other ingredients for life and in the right form e.