CfA reveals Magellanic Clouds are first-time visitors

The Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are two of the Milky Way’s closest neighboring galaxies. A stunning sight in the southern hemisphere, they were named after the Portuguese explorer Ferdinand Magellan, who explored those waters in the 16th century. For hundreds of years, these galaxies were considered satellites of the Milky Way, gravitationally bound to our home galaxy. But new research by Gurtina Besla of the Harvard-Smithsonian Center for Astrophysics (CfA) and her colleagues shows that the Magellanic Clouds are recent arrivals — on their first visit to the Milky Way’s neighborhood.

“We have known about the clouds since the time of Magellan,” said Besla, “and a single measurement has thrown out everything we thought we understood about their history and evolution.”

Although they look like glowing clouds to the unaided eye, the LMC and SMC are both irregular galaxies. The Large Magellanic Cloud is located approximately 160,000 light-years from Earth. It’s about one-twentieth as large as our galaxy in diameter and holds about one-tenth as many stars. The Small Magellanic Cloud is located around 200,000 light-years from Earth. It’s about a tenth the size of its companion and a hundred times smaller than the Milky Way.