September 23rd, 1846

In 1845, a German Astronomer sent a copy of his Ph.D. thesis to the French Mathemetician, Urbain Jean Joseph Le Verrier. Johann Gottfried Galle had written his thesis as a discussion of Danish astronomer Ole Rømer's observation of meridian transits of stars and planets on the days from October 20 to October 23, 1706. Yeah, this was heavy stuff, and interesting to Astronomers, and as Galle hoped, to mathemetician's too. Le Verrier answered Galle's letter months later, on September 18, 1846. Galle received it on September 23, 1846.

Now you are thinking, "Well, benning's gotten too dull for me, I think I'll go take a gander at the porn sites," aren't you? Well, hang in there! This gets interesting!

So what did the French mathemetician say in response to the German astronomer's letter and thesis? Le Verrier asked Galle to look at a certain region of sky to find a predicted new planet, which would explain the perturbations (variations in a designated orbit, as of a planet, resulting from the influence of one or more external bodies) of Uranus. Galle had worked at the Berlin Observatory since it's completion in 1831, working as an assistant to the famed Astronomer, Johann Franz Encke. Galle showed the letter to him, and Encke, against his better judgment gave Galle the go-ahead.

So the very same night, after receiving that letter and request from Le Verrier, Galle and his own assistant, Heinrich Louis d' Arrest, began their search. d'Arrest suggested that a recently drawn chart of the sky, in the region of Le Verrier's predicted location, could be compared with the current sky to seek the displacement characteristic of a planet, as opposed to a fixed star. With Galle at the eyepiece of the great telescope, and d’Arrest reading the chart, they scanned the sky and checked that each star seen was actually on the chart. Just a few minutes after their search began, d’Arrest cried out, “That star is not on the map!”

Galle and d' Arrest had become the first to look at and recognize the newest planet. They had found the last of the great Gas Giants, Neptune. Over the next two days of observations the finding was confirmed. The Solar System now had eight planets! And it happened on September 23rd, one hundred and sixty years ago.

Saturn with her clouds