Neptune the Dreamer

Fact File:

Diameter: 50,000 km

Distance to Sun: 30 AU

Solar Orbit: 165 years

No of Moons: 8

In 1846, the French astronomer Urbain Le Verrier (left) predicted where a new planet beyond Uranus would be found, and it was indeed there: the eighth sphere, the final giant planet in the depths of space. He at once proposed the name 'Neptune' for it, adding that its symbol should be, the Trident. British astronomers were uneasy about this name, however, and instead suggested (about a month after the discovery) that it should be called 'Oceanus'. These names are of interest, because no-one at the time of its discovery had any inkling of its appearance, it was just a speck in the sky. In 1989, after a long sojourn through the depths of space, the Voyager spacecraft arrived at a glorious clear blue sphere, across which there scudded small white clouds. 

The prediction of Neptune's position was the most brilliant moment in the history of astronomy. Le Verrier had been studying the exact orbits of the different planets, and that of Uranus had been out of kilter for some time. Astronomers wondered, whether this could be due to some further sphere, and if so could one hope to find where it was? Le Verrier was confident he could do this, and published two articles concerning its position in the sky, in July and August of 1846. Then he wrote a famous letter to the Berlin Observatory - as no-one in France was taking much notice of him - telling them just where it could be found, in the buttocks of Aquarius. Two astronomers there, Galle and D'Arrest, discovered it within hours of receiving the letter, on 23rd September, 1846 at 23hrs 06 minutes GMT (24h 0 min in Berlin), just before midnight. The prediction had been spot-on, within one degree. The planet was discovered as it wove a triple conjunction with Saturn. (1)


Leverrier's happiness was soon shattered by claims coming over from England, that someone there had done the calculations first. The British astronomers had nothing in writing dated to before the discovery in support of their claims, and it seems to have been very much a case of retrospective prediction on their part. There had been an intensive six-week sky-search conducted at Cambridge to find the new planet (by astronomer James Challis), and how come this had failed when the Germans managed to find it in half an hour? Leverrier and John Couch Adams (the young Englishman who had done the calculations) had a Saturn-Neptune synastry between them (2)

Then American astronomers chimed in, pointing out that the actual orbit of Neptune did not at all correspond with either of the predicted orbits, or only roughly did so for the brief interval when it was discovered. In that case, how had the maths worked so well? The matter was bafflingly obscure, and hinged upon a huge 2:1 resonance going on between Uranus and Neptune, due to one having twice the orbit period of the other. The Americans may have gone too far in claiming that the discovery was a mere 'happy accident.' Neptune had dissolved the credibility of Bode's law, which had worked perfectly well up till then. Both Adams and Leverrier had assumed this law, which put Neptune at twice the orbit-distance of Uranus, but instead it turned out to be much closer, having instead twice the orbit-period of Uranus. Why Bode's law had seemed to work so well was a mystery, but it failed for Neptune. (3)


Within weeks of its discovery, (4) anasthesia started to be used in medicine. The doctor's surgery and the torture-chamber finally parted company. In Britain, in December of that year, the first surgical operation using ether was performed (by James Robinson, who extracted a tooth), and the patient declared she had felt no pain, only 'a heavenly dream' (5)


Across Europe, idealistic revolutions broke out, having utopian goals. The revolutionaries wanted to break with the tired old traditions of the past. That in Paris, was described in Victor Hugo's play 'Les Miserables': it established a republic, with hardly any blood being shed, and promised wonderful things. Marx's 'Communist Manifesto' appeared in 1848, aiming to break the chains of oppression. Wagner was composing his opera, 'Lohengrin.' Also that year the painter Turner composed huge, vague images of sea and storm, an angel and an undine.

Neptune has one large moon, Titan (left), covered with pink snow, with white geyser-fountains that erupt periodically. Nowadays, astronomers believe that 'Neptune seems to consist mainly of a deep layer of water' - in liquid form, (6) as may tend to remind us of the names initially proposed for the new sphere.


LE VERRIER first his learned eye upraised,

And on the problem with fixed purpose gazed:

No inward fears subdued his generous soul;

No dread of censure could his mind control;

The fame of others his bold spirit fired,

And with the hope to emulate inspired.

He passed the barriers of those distant bounds,

Once thought to mark the planet's lonely rounds,

Tracing each wanderer in its varying course,

To each assigning its attractive force;

Planting the flag of Science wide unfurled

Upon the flaming ramparts of the world;

And traversing the Spheres by mental toil,

returns victorious with his well-earned toil.


The Liverpool and Lancashire General Advertiser (weekly) - Friday Dec 11 1846

Neptune, if we could see it moving in the sky, would loop back and forward along the ecliptic every year. Its loops overlap with each other, as you can see from this diagram. It spends about half its time going retrograde, in the middle of each loop, that is about 6 months a year.



(1) - That conjunction was on Le Verrier's natal Mercury, as he sent off his letter to Berlin (18 September): U. Le Verrier was born at 10 am on 11 March 1811 at 49°N07', 0ºW04

(2) - J.C.Adams was born on 5th June 1819.

(3) - Pluto was found, at the Bode-law distance that had been assigned to Neptune

(4) - For recent controversy over Neptune's discovery, see here:

(5) - click here :-
    In October 1846 the first significant surgical operation using anaesthesia was
    performed in Boston.

(6) - Booth 1995, p.140.

Additional Neptune resources:-

The story of how Neptune was found and named: Click here