What is the Small Magellanic Cloud (SMC)?

If you live near the equator or in the Earth’s southern hemisphere and you watch the skies at night, you’re familiar with the Large and Small Magellanic Clouds. These are smaller galaxies nearby the Milky Way, and so they’re close enough and bright enough to see with the unaided eye. Let’s take a look at the Small Magellanic Cloud.

The Small Magellanic Cloud is a dwarf galaxy located about 200,000 light years from the Milky Way, making it one of our closest neighbors. At a magnitude of 2.7, it’s easily visible with the unaided eye from a dark location. Since it’s a galaxy, the Small Magellanic Cloud looks a bit like a detached piece of the Milky Way, over in the constellation of Tucana. Astronomers think that the SMC was once a barred spiral galaxy that was disrupted by the gravity of the Milky Way. It no longer has the familiar spiral arms, but it does still seem to have a central bar structure.

The Magellanic Clouds have been seen by people in the southern hemisphere for thousands of years, but they were made famous by the voyage of Ferdinand Magellan between 1519-22. The clouds were later observed by William Herschel with a 6.1 meter telescope at the Cape of Good Hope. This was a powerful enough telescope to reveal clusters and nebula inside the galaxy.

Astronomers once thought that the Small Magellanic Cloud was a satellite galaxy around the Milky Way, trapped in orbit by our gravity. More recent velocity calculations have thrown that theory on its head though. The Small Magellanic Cloud is moving fast enough that it can’t be captured by our gravity, and must be just passing us by.

We have written many articles about galaxies for Universe Today. Here’s an article about a supernova blowing bubbles in the Small Magellanic Cloud.

If you’d like more info on galaxies, check out Hubblesite’s News Releases on Galaxies, and here’s NASA’s Science Page on Galaxies.

We have also recorded an episode of Astronomy Cast about galaxies – Episode 97: Galaxies.