The planet Neptune has a radius of 15,299 miles and pole radius of 15,125 miles. It has a mass of 102.4E24 kg. Neptune is the forth-largest planet by diameter and third-largest by mass. It is also the densest planet. More » Science Astronomy Planets indicates that Neptune's diameter of 15,299 miles is fourth longest among the planets. At 102 trillion trillion kilograms, Neptune has the third-highest mass of the eight planets in the solar system. However, i... More » Science Astronomy Planets

Neptune is a gas giant and an outer planet. In the solar system, the three other gas giants are Uranus, Jupiter and Saturn. Gas giants are massive planets that have a composition of mainly gases. More »

The smallest planet in the solar system, according to the International Astronomical Union's classification, is Mercury, with a radius of approximately 1,516 miles, which is 38 percent the size of Earth. The next smalles... More » Science Astronomy Planets

Jupiter is the largest planet in the solar system, with a radius of 43,441 miles. That is more than 10 times Earth's 3,359-mile radius, but it is also about 16 times smaller than the Sun's radius. Mercury is the smallest... More »

Neptune is the solar system's farthest planet from the sun, located an average of 2.79 billion miles away. The circumference of its orbit is 17.56 billion miles, more than 30 times the orbit circumference of Earth. Its v... More »

Neptune is the eighth planet from the sun, and it's about 2.8 billion miles away from the sun. This distance is roughly 30 times further away from the sun than Earth is, making Neptune a cold and dark planet. More »