Neptune the Dreamer
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)
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.