Uranus cannot support life as we know it.
Uranus' environment is not conducive to life as we know it. The temperatures, pressures, and materials that characterize this planet are most likely too extreme and volatile for organisms to adapt to.
Ingredients for Life? Jupiter cannot support life as we know it. But some of Jupiter's moons have oceans beneath their crusts that might support life.
Scientists do not believe there has ever been life on Mercury. The atmosphere on Mercury is almost non-existant. It doesn't protect the planet from the harsh radiation of the Sun or radiation from space, nor does it trap heat and provide a breathable atmosphere. Mercury is inhospitable and sterile.
The surface of Mars today doesn't seem like the sort of place hospitable to life. It is dry and cold, plunging down as far as -220 degrees Fahrenheit. Its thin atmosphere cannot block ultraviolet radiation from space, which would devastate any known living thing on the surface of the planet.
It is unlikely that life as we know it could survive on Mercury due to solar radiation, and extreme temperatures.
With extreme surface temperatures reaching nearly 735 K (462 °C; 863 °F) and an atmospheric pressure 92 times that of Earth, the conditions on Venus make water-based life as we know it unlikely on the surface of the planet.
Despite its smaller size, the planet's land area is also roughly equivalent to the surface area of Earth's continents—meaning that, at least in theory, Mars has the same amount of habitable real estate. Unfortunately, the planet is now wrapped in a thin carbon dioxide atmosphere and cannot support earthly life-forms.
Potential for Life
The surface of Pluto is extremely cold, so it seems unlikely that life could exist there. At such cold temperatures, water, which is vital for life as we know it, is essentially rock-like. Pluto's interior is warmer, however, and some think there could even be an ocean deep inside.
The surface of Venus is completely inhospitable for life: barren, dry, crushed under an atmosphere about 90 times the pressure of Earth's and roasted by temperatures two times hotter than an oven.
Saturn cannot support life as we know it, but some of Saturn's moons have conditions that might support life.
Surface. As a gas giant, Saturn doesn't have a true surface. The planet is mostly swirling gases and liquids deeper down. While a spacecraft would have nowhere to land on Saturn, it wouldn't be able to fly through unscathed either.
The Moon's weak atmosphere and its lack of liquid water cannot support life as we know it.
Additionally, Titan's rivers, lakes and seas of liquid methane and ethane might serve as a habitable environment on the moon's surface, though any life there would likely be very different from Earth's life.
Titan's nitrogen atmosphere is so dense that a human wouldn't need a pressure suit to walk around on the surface. He or she would, however, need an oxygen mask and protection against the cold—temperatures at Titan's surface are around minus 290 degrees Fahrenheit (minus 179 Celsius).
Among the stunning variety of worlds in our solar system, only Earth is known to host life. But other moons and planets show signs of potential habitability.
Surface. As a gas giant, Jupiter doesn't have a true surface. The planet is mostly swirling gases and liquids. While a spacecraft would have nowhere to land on Jupiter, it wouldn't be able to fly through unscathed either.
Mars does have an atmosphere, but it is about 100 times thinner than Earth's atmosphere and it has very little oxygen. The atmosphere on Mars is made up of mainly carbon dioxide. An astronaut on Mars would not be able to breathe the Martian air and would need a spacesuit with oxygen to work outdoors.
Perhaps someday, after Saturn's rings have dissipated, the universe might give the planet a new set. “Maybe through some process—another moon is broken apart, a comet comes in too close—and you start it all over again,” Spilker said.
Jupiter: Being a gaseous planet, Jupiter would make for a uniquely uncomfortable life. On — or in? — this enormous planet, "you would descend forever into the gaseous atmosphere until you're crushed by the pressure of the planet's layers."
Evidence points to oceans on other planets and moons, even within our own solar system. But Earth is the only known planet (or moon) to have consistent, stable bodies of liquid water on its surface.
Of course, no lunar life was found in these samples, and we now know that the Moon does not harbor life.
It's relatively cool with an average annual temperature of -60 degrees Celsius, but Mars lacks an Earth-like atmospheric pressure. Upon stepping on Mars' surface, you could probably survive for around two minutes before your organs ruptured.
At Venus, the solar wind strikes the upper atmosphere and carries off particles into space. Planetary scientists think that the planet has lost part of its water in this way over the four and a half thousand million years since the planet's birth. Water is a key molecule on Earth because it makes life possible.
The most acidic rain in the Solar System is found on the planet Venus, where the working fluid in the cycle of evaporation, condensation and precipitation is a sulphuric acid solution (rather than water, as on Earth).