Planet Neptune

Background

Neptune is the slowest of the eight planets in our solar system. It is the eighth and most distant planet from the Sun, at a distance of about 4,500 billion kilometres. With a diameter of about 49,500 km it is the fourth largest planet. Its upper atmosphere gives it a deep sea-blue colour. Neptune cannot be seen from Earth with the naked eye.

Pronunciation: /nɛptjuːn/

Origins, meaning and usage of the name

Because Neptune is the furthest planet away from us, and not visible to the naked eye, it took until 1846 for it to be discovered — by the Frenchman Urbain Le Verrier. The naming process became caught up in a battle for national prestige between France and Britain. The fight was made worse because the leading astronomers (the scientific celebrities of their day) all had very strong personalities. But eventually the pressure to name it in line with the other planets — all but Earth named after Roman or Greek deities — led to the choice of Neptune (Latin: Neptunus), the Roman god of the sea, in recognition of the new planet’s distinct sea-blue colour.

The adjective from Neptune is Nuptunian (capitalized as derived from a proper noun), as in: There are fourteen Neptunian moons. Fictional inhabitants of Neptune are known as Neptunians. Planet Neptune and its moons have featured in various works of fiction.

Above: From the vibrant blues of the Neptunian surface it’s easy to understand what led 19th-century astronomers to associate the planet Neptune with the sea and the Roman god of the sea. (Image: NASA)

Example sentences:

• We learned that Neptune is the windiest of the eight planets. The Neptunian winds can reach sustained speeds of 1,500 mph.
• Planet Neptune is blue in colour and the Roman god Neptune was god of the sea, so that makes sense.

Above: “Neptune, the Mystic” is the seventh and final movement of The Planets (Earth is excluded), written by the English composer Gustav Holst between 1914 and 1916. Its mysterious, other-worldly notes cascade through Neptune’s watery depths as hypnotic choirs float off into the void.