The Large Magellanic Cloud, our galactic neighbor

The Large Magellanic Cloud is a petite galaxy visible with the unaided eye – all year round – for those in the Southern Hemisphere. This small neighboring galaxy to the Milky Way is somewhere between spiral and irregular in shape.

Small, hazy looking bright patches in the starry sky, above observatory domes.

The Large and Small Magellanic Clouds over Paranal Observatory in Chile. Image via the European Southern Observatory.

Southern Hemisphere stargazers can see four galaxies without binoculars or a telescope: the Small Magellanic Cloud, the Large Magellanic Cloud, the Andromeda galaxy and our home galaxy, the Milky Way. The Large Magellanic Cloud appears as a free-floating dusty patch or random cloud in a quiet region of the sky. This hazy patch is a satellite galaxy to our Milky Way. It’s one of the closest galaxies to us at about 200,000 light-years away.

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The Large Magellanic Cloud is about 40,000 light-years closer than the Small Magellanic Cloud and more than 2 million light-years closer than the Andromeda galaxy.

For observers south of about 20 degrees south latitude, the Large Magellanic Cloud is circumpolar, meaning that it can be seen (at least in part) all night every night of the year, weather permitting.

In the Northern Hemisphere, only observers south of about 20 degrees north latitude can ever see it at all. This excludes North America (except southern Mexico), Europe, northern Africa and northern Asia.

Bright, fuzzy oblong in a very starry sky, with some scattered pink spots around it.

This ground-based image of the Large Magellanic Cloud was taken by German astrophotographer Eckhard Slawik. Image via ESA.

Star chart with stars in black on white, with one very large star.

View larger. | The Large Magellanic Cloud is found in the constellations Dorado and Mensa. The nearby star is Canopus.

The Large Magellanic Cloud is located about 22 degrees from the South Celestial Pole, approximately on the border between the constellations Dorado and Mensa in a region of faint stars. It covers an area of sky about 9 by 11 degrees, and shines with a total integrated magnitude of approximately zero. If all of its light were concentrated in a starlike pinpoint, it would be one of the brightest stars in the heavens. However, since the light is spread over nearly 100 square degrees, it appears only as a faint smudge.

From tropical latitudes in the Northern Hemisphere, where it still can be observed, the Large Magellanic Cloud is best seen in the evening from December to April. When the constellation Orion reaches its highest point in the sky, so does the Large Magellanic Cloud.

But, even at 15 degrees north latitude (the latitude of Central America), the Large Magellanic Cloud never gets far above the southern horizon.

You won’t need to starhop to this object unless your sky is really bright. In a dark sky, you can just see it, using your eye alone. However, it’s fairly easy to star-hop to this southern treasure by using the two brightest stars in the nighttime sky: Sirius and Canopus. Draw a line from Sirius and past the right side of Canopus to descend to the Large Magellanic Cloud.

Thin white streak in dark sky between two small, bright fuzzy patches.

A Perseid meteor streaks between the two Magellanic Clouds in August 2013. Photo by Colin Legg.

History and myth of the Large Magellanic Cloud. Being so far south on the sky’s dome, the Large Magellanic Cloud was not known in classical northern mythology at all. Understandably, it fares better for observers in the Southern Hemisphere. The nearby constellation Mensa (“Table”) originally was named after South Africa’s Table Mountain, and a story from that country equates the Large Magellanic Cloud with a puff of smoke from a pipe-smoking contest held on the mountain. Australian Aboriginal storytellers relate that the Large Magellanic Cloud is the campsite of an old man, whereas the Small Magellanic Cloud is the campsite of his wife. The couple, known jointly as Jukara, had grown too old to feed themselves, so other star beings bring them fish from the sky river we know as the Milky Way.

The European “discovery” of the Large Magellanic Cloud and Small Magellanic Cloud is attributed to explorer Ferdinand Magellan, although such obvious heavenly bodies certainly were seen before.

Large oblong of stars, showing faint structure, in very dark starry sky, surrounded by pink spots.

Large Magellanic Cloud as captured by astrophotographer Justin Ng of Singapore. Justin was at Mount Bromo, an active volcano in East Java, Indonesia, when he took this photo.

Science of the Large Magellanic Cloud. The Large Magellanic Cloud is the third closest galaxy to the Milky Way (after two smaller galaxies not visible to the human eye), and the Large Magellanic Cloud is thought by most astronomers to be orbiting the Milky Way.

Although there is some uncertainty due to various methods of distance determination, the best current estimate puts the Large Magellanic Cloud at 150,000 to about 160,000 light-years away, or about five or six times as far from Earth as Earth is from the center of the Milky Way. Other estimates have it as far as 180,000 light-years.

Its shape suggests a transitional form between a small spiral galaxy and an irregular galaxy. About 30,000 light-years across in the longest dimension, it appears from Earth more than 20 times the width of a full moon.

Estimates vary from a few billion to perhaps 10 billion stars in this galaxy, at best no more than about one-tenth the mass of the Milky Way.

The center of the Large Magellanic Cloud is approximately RA: 5h 23m 35s, dec: -69° 45′ 22″

Pink gas clouds with brilliant stars and irregular dark streaks.

Nearly 200,000 light-years from Earth, the Large Magellanic Cloud, a satellite galaxy of the Milky Way, floats in space in a long and slow dance around our galaxy. As the Milky Way’s gravity gently tugs on its neighbor’s gas clouds, they collapse to form new stars. In turn, these light up the gas clouds in a kaleidoscope of colors, visible in this image from the Hubble Space Telescope. Image via ESA/ NASA/ Hubble.

Bottom line: The Large Magellanic Cloud is a great target for observers in the Southern Hemisphere, and still visible for those in tropical latitudes of the Northern Hemisphere from December to April. This small satellite galaxy is one of the closest to the Milky Way.

Larry Sessions