Earth is the third planet from the Sun and the only place known in the universe where life has originated and found habitability. Earth is the only planet to sustain liquid surface water, with ocean water extending over 70.8% of the planet, making it an ocean world.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit the star. The largest of such objects are the eight planets, in order from the Sun: four terrestrial planets named Mercury, Venus, Earth and Mars, two gas giants named Jupiter and Saturn, and two ice giants named Uranus and Neptune. The terrestrial planets have a definite surface and are mostly made of rock and metal. The gas giants are mostly made of hydrogen and helium, while the ice giants are mostly made of 'volatile' substances such as water, ammonia, and methane. In some texts, these terrestrial and giant planets are called the inner Solar System and outer Solar System planets respectively.
The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within.