| 1. | the ancient Roman god of the sea, identified with the Greek god Poseidon. |
| 2. | the sea or ocean: Neptune's mighty roar. |
| 3. | Astronomy. the planet eighth in order from the sun, having an equatorial diameter of 30,200 mi. (48,600 km), a mean distance from the sun of 2794.4 million mi. (4497.1 million km), a period of revolution of 164.81 years, and two moons. |
| 4. | a township in E New Jersey. 28,366. |
In astronomy, a major planet, the eighth planet from the sun. Neptune is named for the Roman god of the sea. Neptune is similar in size and composition to Uranus. It is usually visible only through a telescope and was discovered in the 1840s. For a period ending in 1999, Pluto's orbit took it inside the orbit of neptune. (See solar system; see under “Mythology and Folklore.”)
Note: Some astronomers have suggested that Pluto is not a planet in the usual sense but is an object more like an asteroid, and that Neptune, therefore, is actually the outermost planet.
Neptune
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