Neptune and the Unbelievers
September 23, 1846
1846 1846
00.07E52.12N
NAT

EIGHTH PLANET, SOLAR SYSTEM
	In 1841, about 60 years after the discovery of the planet Uranus, John Adams of Cambridge University and Urbain Leverrier of Paris noticed that the planet was behaving rather unpredictably, not exactly following the orbit predicted by Newton's and Keppler's theories of planetary motion.
	Independently, they guessed that there might be yet another planet whose pull was affecting Uranus. But where in the endless millions of miles of solar system should astronomers look for this planet?
	Fortunately, both men were brilliant mathematicians. By calculating why Uranus was in the wrong place from time to time, they were able to estimate the orbit of the theoretical planet.
	John Adams was the first to mathematically locate this planet, but just as Uranus was in the wrong place, so was Adams. Instead of applauding his brilliant calculation, the two men who controlled English observatories refused to believe a planet could be located simply with mathematics done by an unknown astronomer.
	While ignoring their own countryman, they paid some attention to the Frenchman Leverrier. On July 29, 1846 the observatory at Cambridge began searching for the planet. But incredibly, the head of the observatory did not look where Adams and Leverrier predicted the planet would be. Having no confidence in their math, he ordered a long, tedious -- and rather carelessly done -- study of a large part of the sky. On August 4 and 12, 1846, the object's position was recorded -- but as a star, not a planet.
	Like Adams, Leverrier was also a prophet without honor in his own country. When his countrymen wouldn't look for the planet either, he sent his work to a German astronomer whom he admired, Johann Galle. Galle teamed up with Heinrich d'Arrest and on Sept. 23, 1846 the two began searching for the planet. Within an hour of their second night's search, they found it -- precisely where Leverrier said it would be.
	Because the planet was blue-green, it seemed appropriate to name it Neptune, after the Roman god of the sea. Other than its orbit and general color, not much was known about Neptune until the Voyager spacecraft arrived on August 25, 1989. Voyager found a stormy world with superhurricanes similar to those on Jupiter.
	The interior two thirds of Neptune is made of melted rock, methane, water, and ammonia. The outer third is storm-swept hydrogen, helium, methane, ammonia, and water. Neptune takes 165 years to orbit the sun, is about 30,000 miles in diameter, and rotates once every 16 hours. It's system of four rings is similar to those of Uranus, being made mostly of dust.
	At the moment, Neptune is actually the farthest planet from the sun, because the ninth planet, Pluto, has a narrow orbit which brings it inside Neptune's orbit.