Neptune is one of the two planets that cannot be seen without a telescope. Neptune is about 30 times as far from the sun as is the earth. Neptune’s diameter is about 30,800 mile (49,500 kilometers) or almost 4 times the earths. The planet is about 17 times as massive (heavy) as the earth, but is not as dense as the earth. It has eight satellites (moons). Astronomers have also detected several rings around Neptune. Neptune travels around the sun in an elliptical (oval-shaped) orbit. Its mean distance from the sun is about 2,793,000,000 miles (4,495,000,000 kilometers). Neptune goes around the sun once about every 165 earth years compared toonce a year for the earth. As Neptune orbits the sun it spins on its axis, an imaginary line through its center. Neptune's axis is not perpendicular