A diffuse fog in the southern sky, the Small Magellanic Cloud (SMC) is one of our Milky Way galaxy’s closest neighbors. Because it cannot be seen from most of North America, northern Africa, Europe or Asia, the SMC remained hidden from the cultures that dominated these continents. But in the Southern Hemisphere, the SMC was more prominent; a regular presence in Australian aboriginal stories, it helped early Polynesian cultures navigate the seas.
Portuguese explorer Ferdinand Magellan was the first to document the SMC and its companion galaxy, the Large Magellanic Cloud (LMC), doing so between the years 1519 and 1522. The galaxy pair was later named for the famous world traveler, who identified them while on his final journey to discover a western route to Indonesia.
A new look at old galaxies
The SMC lies approximately 200,000 light-years from the Milky Way, making it the fourth-closest neighbor to our galaxy, according to NASA’s Imagine the Universe. Along with the Milky Way and the LMC, the SMC makes up the Local Group, a collection of about 30 galaxies located in the same neighborhood.
The SMC stretches across the sky, reaching about 7,000 light-years across, according to the Herschel Space Observatory. Viewers on Earth will see the SMC takes up as much room in the sky as nine or 10 full moons. Relatively small for a galaxy, it may still contain as many as a few hundred million stars, according to EarthSky.org.
The LMC and the SMC share an unusual shape that probably comes from their interaction with one another and with the Milky Way. The pair orbit one another about every 900 million years and circle the Milky Way about once every 1.5 billion years, according to the Swinburne Astronomy Online Encyclopedia of Astronomy.