Astrology

Neptune's discovery by mathematics turns 180 years old this week

Astronomers marked 180 years since the discovery of Neptune on September 23, 1846, when the outermost major planet in the solar system was found through mathematics rather than direct observation, EarthSky reports.

French mathematician Urbain Le Verrier calculated where an unseen planet should be after noticing that Uranus was not following its predicted orbit, and German astronomer Johann Gottfried Galle located Neptune from the Berlin Observatory on the night of September 23-24, confirming Le Verrier's prediction, according to Wikipedia.

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A planet found within one degree of a prediction#

Le Verrier worked out Neptune's position using only the gravitational pull it appeared to exert on Uranus, since the planet cannot be seen without a strong telescope and few existed at the time, Gript reports. Galle went looking on September 23 and found Neptune less than one degree from where Le Verrier had calculated it would be, per Gript.

The French scientist Francois Arago said Le Verrier had discovered a planet "with the point of his pen," according to Wikipedia's account of the discovery, which called the confirmation a dramatic vindication of Newtonian gravitational theory.

Three men are credited with independently working toward the discovery: Galle, Le Verrier and English astronomer John Couch Adams, and their separate efforts led to an international dispute over who deserved the credit, EarthSky reports.

Neptune's moon and its only close-up visit#

Just 17 days after Neptune itself was found, British astronomer William Lassell discovered its moon Triton, according to USA Today.

NASA's Voyager 2 spacecraft made the only close flyby of Neptune in history on August 25, 1989, revealing a massive storm called the Great Dark Spot and discovering six new moons and four rings, EarthSky reports.

That encounter closed out Voyager 2's Grand Tour of the solar system's four giant planets, and no other spacecraft has returned to Neptune since, according to EarthSky.

How the planet compares to its neighbors#

Located in the outer solar system, Neptune ranks as the eighth world from the sun and remains the most distant known planet, orbiting once every 164.8 years at a distance of 30.1 astronomical units, and is 17 times the mass of Earth, according to Wikipedia. It sits an average 4.5 billion kilometres from the sun and takes about 165 Earth years to complete an orbit, Starts at 60 reports.

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