A realistic timelapse seen from neptunes moon (360° VR Simulation Video). Another timelapse simulation, this time from the moon of the planet neptune. Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, and slightly more massive than its near-twin Uranus.