Our planetary system is called “the solar system” because we use the word “solar” to describe things related to our star, after the Latin word for Sun, "solis. " So far, we've only know about life on Earth, but NASA is searching for life on other worlds in our solar system . The Solar System is the gravitationally bound system of the Sun and the masses that orbit it, most prominently its eight planets, of which Earth is one. The system formed about 4. The four inner terrestrial planets are Mercury, Venus, Earth, and Mars, all of which consist mainly of rock. The universe is filled with billions of star systems. 5 billion years ago when a cloud of interstellar gas and dust collapsed, resulting in a solar nebula, a swirling disc of material that collided to form the.