As of this writing, around 150 planets have been discovered. This number is not exact because new planets are discovered all the time, as well as mistakes are admitted. Sometimes scientists think they have discovered a planet (which revolves around stars), but then find out it was just a moon (which orbits planets) or a comet with an errant trajectory. If finding a new planet sounds easy, discovering life beyond Earth has so far been an impossible task. Almost all of the planets on the list are gas giants, thousands of times the mass of Earth. From experience with planets this size in the solar system, it is very likely that most of them have toxic atmospheres and immense gravity, scuppering any chance of life. So far, the strongest candidate for life is an as-yet-unnamed planet discovered in June of this year. It orbits the star Gliese 876d, 9.5 trillion kilometers away from us. Astronomers’ biggest reason for hope is that this Earth candidate is not made almost entirely of gas, but mostly of rock and metals, just like our planet. “This is the smallest planet outside the solar system ever detected and the first of a new class of rocky planets. It’s like a bigger cousin of the Earth”, says astronomer Paul Butler, from the Carnegie Institution, in the United States.
Planet 9.5 trillion kilometers away could support life
HOT, HOT, HOT
Due to its proximity to the star Gliese 876d, the planet is an oven. Scientists think that a thermometer there would mark something between 200 and 400 ºC! Anyone who wanted to enjoy this infernal heat would see a red sun and two neighboring gas giant planets on the horizon.
BIG AND HARD
Calm down, it’s not what you think: the planet is about 5 to 8 times bigger than Earth. He’s big, but he’s not a gas giant, which has hundreds of times more mass. The soil is speculated to be rocky, probably containing nickel and iron.
ALMOST HUMAN
For humans, this planet would be very hot and very toxic. But hypothetically, there could be humanoid beings. They would need to have very thick skin, resistant to high temperatures and stellar radiation, as well as being able to breathe excess steam.
SOLZINHO MIXURUCA
The planet is 3.2 million kilometers from its star, Gliese 876d. That’s only 2% of the distance between the Earth and the Sun. But Gliese 876d is a red dwarf with a third the mass of our Sun, and it produces about 10% of our star’s heat.
VITAL STEAM
Here begin greater similarities with Earth. “It is possible that the atmosphere has a dense layer of water vapour”, says the American astronomer Gregory Laughlin, from the University of California. With water in the air, it increases the possibility of life, especially simple forms like microorganisms.
Scientists are looking for microorganisms in two places in the solar system
MOON EUROPE
Data from the Galileo space probe show that this moon of Jupiter may have an ocean ice. “This suggests that the environment could support life,” says American astrophysicist Mark Burchell, from the University of Kent.
MARS
The passage of the robots Spirit and Opportunity by the red planet in 2004 indicated the possibility of frozen water and gases in the atmosphere, which could provide conditions for our neighbor to have at least some living microbes