Bend in the Big Dipper’s handle


Even the most familiar astronomical objects have hidden depths if you think of them as mirrors. Look at a familiar star grouping like the Big Dipper, and perhaps you will see its very human face staring back at you.

I could go on forever about the Dipper. I could do so again about the Dipper’s handle. Shoot, I could write a column or two about the bend in the handle. So perhaps I shall.

At that bend is the Dipper’s most famous star, Mizar.

Like most of the brighter stars in the sky, Mizar was named by Arab astronomers. Its name suggests an abdominal covering like a girdle or apron.

Hovering near Mizar is the somewhat fainter Alcor. Its name probably derives from the Arabic Al-jat, “The Rider.” The stars together are often called the Horse and His Rider.

I will write about their scientific attributes next week. For now, let’s look at their histories.

The two stars have been horsing around for a long time. In England, people called bright Alcor “Jack on the Middle Horse.” Mizar is Jack’s starry steed.

Along with the other stars in the handle of the Dipper, Mizar is part of the team of horses that pulls a plough. In fact, the Big Dipper looks as much like a plow as it does a water dipper.

The Romans sometimes called Alcor Eques Stellula, the “Little Starry Horseman.”

The Dutch believed the horseman was Hans Duemken, a legendary wagon driver who spent eternity driving his team of horses across the sky. Again, the stars in the handle form the horses, and the bowl of the Dipper is the wagon.

Because of its proximity to Mizar, Alcor often plays second banana to the brighter star. The Arabs sometimes called Alcor Suha, the “Forgotten One.” The Chinese called it Foo Sing, “Supporting Star.”

In other cultures, Alcor is a victim of celestial circumstance. Far to Mizar’s south is a cluster of six stars enigmatically called the Seven Sisters. So, what happened to the seventh star?

The people of Mongolia say that the missing star migrated far to the north to become the star Alcor. In that story, the other, brighter stars of the Dipper are known as “robber stars,” proud of their brilliance and anxious to add bright stars to their gang.

On one raid, they carried one of the Seven Sisters back to their perch near Polaris, where it must shiver forever in the icy north. Alcor is known as the Cold Star because it had been kidnapped from the southern, warmer region.

Some modern writers believe that the Arabs considered Alcor a test of vision, a celestial eye chart.

However, Alcor isn’t much of a test. Your eyesight must be poor indeed if you can’t spot it on a moderately clear night.

A small telescope reveals a hidden secret — a star between Alcor and Mizar with the strange name of Sidus Ludoviciana, Ludwig’s Star. It was discovered telescopically on Dec. 2, 1722, by Johann Georg Liebknecht, an astronomer at Ludoviciana University, located in Giessen in the German province of Hesse-Darmstadt.

Herr Professor Liebknecht mistook the star for a planet and thought he had made a momentous discovery. He also knew what side of the bread his butter was on.

To curry favor (and perhaps gain a bit of financial patronage), he named the “planet” after Louis V, “Ludwig” to the Germans, the duke of the local province. Note that the university, Ludoviciana, was also named after Ludwig.

Other astronomers soon identified it as a simple star, and stars are common as dirt in the sky. However, the name remains as a testament to the need for poor scientists to receive funding from wealthy and powerful patrons.

Sidus Ludoviciana has one more strange aspect. At 8th magnitude, the star is well below naked-eye visibility. Spotting such a faint star with the unaided eye would take almost superhuman vision.

Despite that fact, the late, great British astronomy writer Sir Patrick Moore suggested that the Arabs meant Sidus Ludoviciana — and not the more obvious Alcor — when they referred to a star near Mizar as a test of vision.

Sorry, Sir Patrick. I don’t think so.

Tom Burns is the former director of the Perkins Observatory in Delaware.

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