It is exciting to read the discovery of exoplanets because it is news that makes us hope not to be there unique forms of life in the Universe. Each time you add another name to the list of exoplanets, you imagine that you have found another world to explore and inhabit.
Discovery of exoplanets: what they are
Exoplanets are also called extrasolar planets and are planets that simply do not belong to the solar system and therefore find themselves orbiting around a star other than the Sun. In fact, these planets are located outside our own Solar system.
It comes natural to wonder how many there are. We can start counting the ones we have discovered so far. Up to 30 November 2018, 3,901 were known inserted in 2,907 different planetary systems. It's not over: there are also other planets that could be exoplanets but they are still to be confirmed and they are 2,443, other 213 possible planets are pending confirmation or controversial.
In the long list of exoplanets discovered we can remember the thousandth, reached on 22 October 2013, with the announcement of 11 hot Jupiters by the SuperWASP project. The two thousandth is instead Kepler-406 b, an exoplanet discovered in 2014 and confirmed on 25 November 2015 as part of the Kepler mission with the transit method.
Discovery of exoplanets: tools
In order to be able to discover and identify the presence of planets outside our solar system in space, indirect observation methods and also telescope observations are used. Today, however, observation techniques have considerable limits, this therefore implies the fact that most of the planets identified are gas giants like Jupiter, far fewer are the massive rocks of the Super Earth type among those identified.
Thanks to the arrival of the Kepler mission many more small planets have been discovered because this mission has made it possible to define an outline of exoplanetary classification based on their size. To date, several telescopes and instruments designed specifically for the identification of exoplanets are under construction, including theAutomated Planet Finder, CHEOPS and the TESS space telescope which would actually already be operational from June 2018.
Discovery of exoplanets: history
It is not a recent discovery that ofExistence of exoplanets, however, interest in them is growing. Especially since 1992, the year of the first confirmed discovery, more and more attention has begun to these planets outside the solar system. Partly for reasons of instrumentation, partly for reasons of time, the pace of the first discoveries was really slow, but in the last period there has been a considerable acceleration. In 2000, "only" 20 planets discovered but already in 2011 there were 189 new ones to add to the list, in 2015 even 2000.
The scientific community is divided in the face of these planets orbiting gods stars very similar to the Sun, some astronomers argue that only 10% of solar-type stars have their own planetary system but there are other experts who believe it is normal for a solar star to have one.
Why so much interest in exoplanets? It is not only a passion for space and astronomy, but also the hope of finding other worlds different from ours but capable of hosting a form of extraterrestrial life. Kepler-22 b - rotating around a yellow dwarf, Kepler-22, approximately 600 light years away from the Solar System, would appear to have been the first terrestrial-type exoplanet which was discovered orbiting its system's habitable zone in 2011.
This means for example that it could have an average surface temperature of around 22 ° C which it would allow the presence of liquid water, essential to allow life in these parts. In 2015, another exoplanet was identified, Kepler-442 b, which turned out to be the closest planet to Earth ever identified.
Recent discovery of exoplanets
The discovery of exoplanets 7 planets that are located outside our Solar System dates back to 2017, it is an important discovery because it would be exoplanets very similar to Earth in several respects, so they could host traces of liquid water and therefore some form of extraterrestrial life. Just what many are hoping for. To know more is necessary wait for 2020 when the launch of the James Webb Telescope will be made, which will reveal if there really can and does life exist on this planet.
The 2017 discovery was announced by NASA on February 22, the protagonists were some astronomers led by Michaël Gillon of the STAR Institute of the University of Liege. What has emerged so far about these 7 planets is that they are rocky planets with similar size and mass to Earth. They have circular orbits and they all turn in the same direction. Among the seven there are three that are located in the habitability belt of their star because they receive a sufficient amount of energy to suggest the presence of optimal temperatures for the discovery of liquid water and any forms of life.
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