FACTS ABOUT NEPTUNE ~It takes Neptune 164.8 Earth years to orbit the Sun. ~Neptune was discovered by Jean Joseph Le Verrier. ~ Neptune is the Roman God of the Sea. ~The largest Neptu nian moon, Triton, was discovered just 17 days after Neptune itself was discovered. ~ Neptune has an average surface temperature of -214°C 7 Fun Facts About Neptune 1. Neptune is about four times wider than Earth. If Earth were a large apple, Neptune would be the size of a basketball. 2. Neptune orbits our Sun, a star, and is the eighth planet from the Sun at a distance of about 2.8 billion miles (4.5 billion kilometers). 3. Neptune takes about 16 hours to rotate once (a Neptunian day), and about 165 Earth years to orbit the sun (a Neptunian year). 4. Neptune is an ice giant. Most of its mass is a hot, dense fluid of "icy" materials – water, methane and ammonia – above a small rocky core. 5.Neptu ne's atmosphere is made up mostly of molecular hydrogen, ato