Neptune is the aicht an farthest planet frae the Sun in the Solar Seestem. It is the fowert-lairgest planet bi diameter an the third-lairgest bi mass. Amang the gaseous planets in the solar seestem, Neptune is the maist dense. Neptune is 17 times the mass o Yird an is slichtly mair massive than its near-twin Uranus, which is 15 times the mass o Earth but nae as dense. On average, Neptune orbits the Sun at a distance o 30.1 AU, approximately 30 times the Yird–Sun distance. Named for the Roman god o the sea, its astronomical seembol is ♆, a stylised version o the god Neptune's trident.