The Sol System is the considered the center of human space and his where the human home planet of Earth is located. At its center is a G-type main-sequence star known as Sol, or the colloquially "the Sun", after which the system is named. In addition to Earth, the planets of the Solar System are, in order of their distance from Sol: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Persephone, Caïna, Antenora, and Ptolomaea. Earth is the third planet from Sol and Pluto is an escaped moon of Neptune. In addition there are many other objects outside of these orbits that travel around Sol, as well as an asteroid belt closer to the Sun and various meteors and other extraterrestrial objects. Although some planets in the Sol System are comprised of gas, and none are particularly suitable for sustaining human life, the entire system has been explored and colonized to the extent that the current technology will allow.