The Planet that Wasn’t

Within the famous star pattern we call the Big Dipper, we can can find the star Mizar, the middle star in the dipper’s handle. Mizar has a fainter companion, about one-fourth as bright, known as Alcor. When Mizar and Alcor are viewed through a telescope, the two appear bright and far apart from each other. But that’s not all. Mizar itself is separated into two stars very close together.

Back in 1722, a German mathematics professor, J.G. Liebknecht, was examining Mizar with a crude telescope and chanced upon a faint star between Mizar and Alcor.

With some fanfare, he announced that he had discovered a new planet, and named it “Sidus Ludoviciana” or “Ludwig’s Star” after his sovereign, the Landgrave Ludwig of Hessen-Darmstadt. But the reaction from other astronomers throughout Euorpe was universally unfavorable, as they noted that Liebknecht’s “new planet” was merely a fixed telescopic star.

Nonetheless, to this day, the star still retains the name that was bestowed upon it by Liebknecht when – for a few months anyway – it was thought to be a planet.