Neptune is now the farthest planet from the sun, since the elimination of Pluto. It is 4,504,000,000 km away from the sun and has a diameter of 49,532 km (4th largest). Neptune has a mass of 1.0247e26 kg, which is the 3rd largest by mass. A day on Neptune is 16 days and 6.7 minutes and it orbits the sun every 167 years. Neptune was first discovered by Johann Galle and is named after the god of sea.