What are the Clouds of Magellan?

Identification

• Between 1519 and 1522, an expedition led by Portuguese explorer Ferdinand Magellan became the first to circumnavigate the globe. When they sailed into the Southern Hemisphere, the sailors noticed two cloudy patches in the night sky. Magellan died during the journey and historians believe it was unlikely that he was the one who first spotted and recorded the sighting. However, since it was his expedition, the astronomical features became known as the Clouds of Magellan.

History

• The Clouds of Magellan were known to ancient astronomers hundreds of years before Magellan sailed. In 964 A.D., Al Sufi of Persia described their location in the sky and called them the "White Ox of the Southern Arabs" since they could only be seen in the Southern Hemisphere. They were also called the "Nubecula Major and Minor" by Johann Bayer of Germany. British astronomer John Flansteed simply called them "Large Cloud and Small Cloud."

Time Frame

• Magellan was not an astronomer. He and his sailors had no idea what they were seeing. The Clouds of Magellan are actually relatively small galaxies on the outskirts of our own. In fact, they are the two closest galaxies to Earth. The larger galaxy is about 170,000 light years away while the smaller galaxy is about 190,000 light years away. This is quite close in astronomical terms.

Function

• Modern astronomers refer to the Clouds of Magellan as the Large Magellanic Cloud and the Small Magellanic Cloud. Each of them is composed of about 10 billion stars, which is rather small in astronomical terms. The LMC is about 1/3 the size of the Milky Way while the SMC is about 1/5 of its size. The Clouds of Magellan are asymmetrical and therefore look much different than the spiral shape of the Milky Way. Astronomers believe that they are linked to the Milky Way by cold hydrogen gas. The Clouds of Magellan are also believed to be moving toward the Milky Way and will eventually be sucked in and consumed by it.

Features

• The Clouds of Magellan are popular with amateur astronomers. They are relatively easy to find and see on a clear, dark night in the Southern Hemisphere. The Large Magellanic Cloud can be found in the Mensa and Dorado constellations. The Small Magellanic Cloud can be seen in the Tucana constellation.