Life on other planets

“The history of life on a planet mirrors the planet's life history.”

Last week, the NASA space telescope Kepler which should be searching for planets similar to Earth that orbit stars near to our galaxy did not function and does not seem to be fixable.

Kepler cost 550 million dollars. It was launched in 2009, and has found 132 planets which could be habitable. Scientists have found other 2,740 planets which should be analyzed in more details with telescopes from Earth which will confirm whether or not the aforesaid planets are habitable.

Stars that have planets which orbit around them is a very old idea originating from Greece. The existence of other worlds was suggested by philosophers at that time. There is an infinity of worlds in the space with probably some similar to our world.

In the sixteenth century, Giordano Bruno, an Italian Dominican friar, philosopher, mathematician and astronomer, speculated about the existence of other worlds which could be habitable like Earth in his work On the Infinite Universe and Worlds.

Four centuries have passed, and nowadays, observation of other planets similar or like Earth is carried out instead of the speculation about likewise planets. "Comparative planetology", a new branch of astronomy, consists of studying and contrasting properties of numerous planets in detail.

Owing to comparative planetology, we know that most stars have planets orbiting around them, that life on planets is only possible with regular astronomical properties, and quite narrow chemical composition. Whereas simple bacterial life may be prevalent, complex life may not be ubiquitous.

Scientists defines life as carbon-based and operating in water, but there may be other types of life which could be silicon-based, and operating in ammonia. As a point in case, intelligent life could have evolved more than we can imagine, and maybe can leave behind its physical carbon envelope.

There are hundreds of billions of other planets in our galaxy, and with their moons, we can count trillions of other worlds. By the same token, there are “hundreds of billions of other galaxies across space”. Some planets will have the same properties than Earth. Life on each of these planets will be specific to them, and will depend on the planet’s history. Each planet has a unique history which winds up in this planet being unique in the Universe.

The observation of other planets will continue as Kepler's mission will be carry on by other space telescopes.

Source: http://www.npr.org/blogs/13.7/2013/06/05/188321257/other-planets-from-speculation-to-confirmation