By Olivia Solon, Wired UK

On 12 July, Neptune will celebrate its very first birthday because exactly one Neptunian year — or 164.79 Earth years — will have passed since its discovery.

Neptune was mathematically predicted before it was first telescopically observed on 24 September 1846. Astronomer Johann Gottfried Galle and his assistant Heinrich Louis d’Arrest used Urbain Le Verrier’s calculations to locate the planet. It was found to be within a single degree of where Le Verrier had predicted it would be and it was the first planet to have been discovered deliberately.

Its position was worked out because astronomers had mapped the orbit of Uranus and detected irregularities in its path that could only be explained if the gravity of a further, separate and unknown planet was disturbing its path around the Sun. This triggered a hunt for an eighth planet.

Once Neptune was discovered, it took just seventeen days for William Lassell to find its moon Triton. None of its other 12 moons were found until the 20th century. Neptune is the fourth-largest planet in diameter and the third largest in terms of mass — 17 times that of Earth — in the solar system. It is also the farthest planet from the Sun since Pluto’s demotion in 2006.

The gas giant is often lumped together with Uranus under the label “ice giants” due to the fact that they are smaller and have a higher proportion of “ices” (such as water, ammonia and methane) then Jupiter and Saturn. Its atmosphere is composed primarily of hydrogen and helium and it’s pretty chilly, with temperatures approaching -218 degrees C. It’s also pretty windy, with gusts reaching speeds of up to 1,200 miles per hour.

Neptune’s only earthly visitor has been the Voyager 2, which flew past the planet in August 1989. NASA has researched possibilities for Cassini-Huygens-like probes, but budgetary constraints have so far failed to allow one to be funded.

In the meantime, do join us in wishing Neptune the warmest of birthday greetings.

Image: NASA

Source: Wired.co.uk

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