By Ashley Mackenzie | Updated March 24, 2022
Although they orbit the same star, Earth and Neptune differ dramatically. Earth sustains life, while Neptune remains a distant, gaseous giant. The following comparison highlights their distinct physical and orbital characteristics.
Neptune’s diameter is 30,775 mi (≈49,528 km), nearly four times Earth's 8,000 mi (≈12,800 km) diameter, as confirmed by NASA. This makes Neptune the fourth‑largest planet in our system.
Both planets follow elliptical orbits. Earth completes one orbit every 365.25 days, whereas Neptune takes a staggering 164.8 years to travel around the Sun.
Earth’s rocky terrain and liquid water provide a solid foundation for life. Neptune, a gas giant, lacks a true surface; its outer layers consist of silicates, water, hydrogen, and helium, creating a deep, fluid envelope.
Neptune’s atmospheric winds can reach up to 700 mph (≈1,120 km/h), far surpassing Earth’s record of 231 mph (≈372 km/h) set at Mount Washington in 1934.
Earth has a single natural satellite. Neptune boasts 14 known moons, including the sizeable Triton, and three faint ring arcs—features absent on Earth.
For more detailed planetary data, visit NASA’s planetary science portal.
