The Solar System
The solar system consists of a medium size star (Sun), four Earth planets formed by rock and metal (Mercury, Venus, Earth and Mars), four giant gaseous planets formed by helium and hydrogen (Jupiter and Saturn) or frozen water, Ammonia and methane (Uranus and Neptune).
The solar system also has several regions composed of small objects. The asteroid belt, located between Mars and Jupiter, is similar to the terrestrial planets in terms of its composition and it is the dwarf planet Ceres. Beyond the orbit of Neptune are the belt of Kuiper, the scattered disk and the cloud of Oort, which include Neptunian objects as the kites formed by water, ammonia and methane mainly.
In this place there are four dwarf planets called Haumea, Makemake, Eris and Pluto.
The Solar system has, in turn, 400 natural satellites, 587479 planetoids or minor planets and 3153 kites. So far, of all of them, only life has been found on Earth even though the astrobiologists seek signs of life in microbial form or Extremófila on Mars, Titan, Europe or Encelat.
Extrasolar Planet or Exoplanets
An exoplanet is a planet orbiting around a body outside the solar system. The first confirmed detection was made in 1992, with the discovery of several terrestrial mass planets orbiting the Lich Pulsar 1. In 1995, the first detection of an extrasolar planet, called Dimidio or 51 Pegasi B, was confirmed, orbiting around a star, Helvetios, of the Pegasus constellation. It has a minimum mass 150 times greater than the Earth, so it is believed to be a gaseous giant.
Since then, the number of exoplanets discovered has grown exponentially and has depended on the method used. Between the year 2011 and 2015, 191, 154, 189, 841 and 165 were detected, respectively.
Press timing: This method was used to detect the first exoplanets, since they orbit a pulsar, a neutron star that emits radiation periodically by spinning on itself at high speed. Variations in their periodicity are motivated by the influence of an exoplanet.
Transit: When a planet passes in front of a star blocks part of the light that we. If this decrease is perceived periodically, it is deduced that the planet orbits the star. This is the most used method to detect exoplanets, with 2569, up to the year 2016.
Kepler-452b: It is the first planet of the size of the Earth discovered orbiting in the habitable zone of a star very similar to the sun. With a radius of 60% greater than the Earth and an orbit of 385 days.
Radial velocity: This method uses Doppler spectroscopy to detect changes in the position of the star, which moves away and approaches the earth, as a consequence of the exoplanet and it orbit around a common mass center. This method is noticeable when exoplanets are massive. This is the second most prolific method with 585 to 2016.
Direct image: The first exoplanet photographed through its direct vision was the Beta Pictoris B, in 2008, thanks to the “very Large Telescope” of Chile. It is located at 63 light-years from Earth and has a mass between 4 and 11 masses of Jupiter.
Gravitational Microlens: This method is given when the gravitational fields of the planet and the Star Act to increase or focus the light of a distant star, this happens when the star, the exoplanet and the Earth are aligned, fact that occurs only once. Thus the first planet of low Mass was discovered in a wide orbit, called OGLE-2005-BLG-390.