A team of British and German space scientists using ground-based telescopes in Chile have spotted an Earth-like planet revolving around a Sun-type star just about 44 light years away from our solar system. The newly-discovered planet is believed to have atmospheric and other conditions that make it very similar to Earth. Of all the Earth-like planets found to date, it’s the closest to us.
More than 800 planets have been discovered outside the solar system over the past two decades, the majority of them being gas giants like Jupiter or solid planets too close to their stars and therefore too hot to support water.
The new planet is in the so-called “habitable zone”, which means that it may have water in a liquid state, and it also has an axis of rotation. The latter increases chances that it may support Earth-type life, says astrophysicist Sergei Smirnov of Russia’s Pulkovo Observatory.
“It’s important that its rotation should not be synchronous like that of our Moon, which is a reason why only one side of the Moon permanently faces Earth. And also, its revolution period or the length of year should differ from its rotation period or the length of day. This is an additional factor that helps sustain a biosphere. The light-and-shadow cycle and the temperature cycle are also very important. Humans are accustomed to a change of light. We can equally endure full darkness and blistering sun on a sand beach or snowfield. The same is true of cold and heat. Some living organisms can survive in a far wider range of temperatures.”
The new planet is 7 times the size of Earth. Higher gravity, though unlikely to affect the climate, could result in smaller forms of life, says Sergei Smirnov.
“Suppose, advanced forms of life emerge there, like elephants here on Earth. Then, in all probability, they would be smaller and flatter due to higher gravity. There would be no large species.”
Oleg Malkov, a laboratory head at the Russian Institute of Astronomy, believes that the presence of a biosphere does not necessarily require Earth-like conditions.
“There is only one type of life in the Universe that we know of – our own. Therefore, we are looking for planets that resemble Earth in mass, size, distance from the central star and all other parameters. Thus, chances that Earth-type life does exist are increasing. But life may have other forms.”
Sergei Smirnov agrees:
“The “habitability” theories are based on scientific discoveries made in the mid-20th century. Today, we should take a broader look at potential forms of life in various temperature ranges, and in planetary atmospheres, oceans and solid surfaces of various chemical composition. In the solar system, moons of giant planets are likelier to have some forms of life than Mars. For example, Europa the size of our Moon has a thick ice shell that can possibly hold the largest amounts of liquid water in the solar system, where life is possible.”
Theoretically, there may be sulphuric-phosphate and silicon forms of life that do not require an atmosphere with a high concentration of oxygen. Incidentally, spectroscopic studies of exoplanets show that their atmospheres are oxygen-free.