Some scientists think the two regions might have once comprised a single spiral galaxy, but there is no way to be certain. The Large and Small Magellanic Clouds are both visible together from the southern hemisphere of the Earth. The cosmic structure is so close to the Milky Way Galaxy that the clouds actually feed the Milky Way gas and dust. It is possible the clouds may eventually collide and merge with this galaxy.
Large Magellanic Cloud Profile
Type: Disrupted Barred Spiral
Diameter: 14,000 lightyears
Distance: 163,000 lightyears
Mass: 10 billion solar masses
Constellation: Dorado & Mensa
Discovery Date: First described in 964 A.D.
Approximate Number of Stars: 30 billion
Small Magellanic Cloud Profile
Type: Dwarf Galaxy
Diameter: 7,000 lightyears
Distance: 197,000 lightyears
Mass: 6.5 billion solar masses
Constellation: Tucana & Hydrus
Discovery Date: late 1400s
Approximate Number of Stars: 3 billion
Magellanic Clouds Facts
• Despite the relative proximity of these clouds to each other, the Small Magellanic Cloud is about 35,000 lightyears farther away from Earth.
• It was once commonly accepted that the Magellanic Clouds were in orbit around the Milky Way Galaxy, but new evidence shows their relative speed might be too high for that to be the case.
• As one might guess, these clouds are comprised mostly of different gaseous elements, and that means the presence of metallic elements is greatly diminished.
• Gravity affects the Magellanic Clouds when they pass by the Milky Way, and it causes the shapes of the clouds to distort. The same effect occurs on the outer edges of the Milky Way itself.
• Some researchers believe the Small Magellanic Cloud was once a single galaxy, and that the galaxy that spawned the Large Magellanic Cloud collided with that single galaxy to form the cosmic patterns that exist today.
• The Tarantula Nebula is part of the Large Magellanic Cloud, and it is one of the most active star-birthing regions visible to man. Gas and dust are highly compressed in the area, and the site also saw a supernova explosion in 1987.
An In-Depth Look at the Magellanic Clouds
The Magellanic Clouds are members of the Local Group of galaxies that refers to galaxies close by the home galaxy of mankind, the Milky Way. The clouds are comprised of two primary regions known as the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). Both structures are visible from the southern hemisphere with the naked eye assuming favorable conditions, and they are sometimes called spiral galaxies as opposed to irregular galaxies.
Early peoples would use the Magellanic Clouds as navigational tools since they were steady in the sky and could easily be recognized. There is evidence of discussion of the clouds as far back as the first millennium, and a Persian astronomer called Al Sufi was almost certainly describing the LMC in 964 when he released his Book of Fixed Stars.
Two Italian explorers were the first Europeans to observe and describe the Magellanic Clouds. Their discovery was made in the late 1400s, and within several years other Europeans were using the clouds to aid in sea travel. Ferdinand Magellan himself, for whom the clouds were named, used the structures to help him circumnavigate the world in the early 1500s. It wasn’t until quite some time later that the cosmic clouds were renamed after the famed explorer. Before then, they were typically called simply ‘The Large Cloud’ and ‘The Small Cloud’.
When viewed from the southern hemisphere, the LMC and the SMC seem as if they might merely be disjointed pieces of the Milky Way that are floating through space, but the vast distances at play cause that illusion. They were the closest catalogued galaxies to the Milky Way until the Sagittarius Dwarf Elliptical Galaxy was discovered in 1994. The LMC is about 163,000 lightyears from Earth, and for a reference scale, the entire Milky Way Galaxy has a diameter of 100,000 lightyears.
The Magellanic Clouds, up until quite recently, were assumed to orbit the Milky Way at relatively constant distances. However, the clouds are currently closer to the Milky Way than they have ever been, and the relationship between the clouds and the Milky Way is starting to seem much more complex. Tidal interactions between these major sources of gravity have taken their toll, and the gases that are being collected from the clouds by the Milky Way are only strengthening the connection.
There are two primary differences between the Magellanic Clouds and the Milky Way. The clouds are much more gas-rich, specifically in helium and hydrogen, than the Milky Way, and they also include far less metal. In the case of the SMC, the dwarf galaxy only contains metals at a concentration of one quarter that found in the Milky Way. The abundance of pressurized gases and relative lack of heavy metals causes new stars to form quite rapidly within several notable nebulae, and there are stars in the clouds that have been around for billions of years.