Clusters Nebulae Galaxies

Small Magellanic Cloud orbits our Milky Way

Image via NASA.
The Small Magellanic Cloud, via NASA.

How to see the Small Magellanic Cloud

You’ll see the Small Magellanic Cloud from Earth’s Southern Hemisphere. It’s even farther to the south than its larger cousin, the the Large Magellanic Cloud. These two hazy patches in the southern sky are really separate galaxies from our Milky Way. They are satellite galaxies to the Milky Way, orbiting around it.

The Small and Large Magellanic Clouds are never seen north of about 17 degrees North latitude. The Small Magellanic Cloud isn’t visible from North America (except far southern Mexico), northern Africa, and all of Europe and Asia (except the southern regions of India and Southeast Asia).

From more northerly latitudes where it still can be observed, the Small Magellanic Cloud is best seen in the evening in late autumn and early winter (late night in October, mid-evening in November and December, and early evening in January). Whenever the W or M-shaped constellation Cassiopeia the Queen climbs to her highest point in the northern sky, look for the Small Magellanic Cloud to soar to its highest point in the southern sky.

The Small Magellanic Cloud is located about 20 degrees from the South Celestial Pole, in the southeast corner of the constellation Tucana. To find where the Small Magellanic Cloud lies, look about 15 degrees below the bright far southern star Achernar in the constellation Eridanus the River. For reference, a fist-width at an arm length equals about 10 degrees. Eridanus the River meanders all the way from the Orion star Rigel to Achernar, the end of the River.

The Small Magellanic Cloud is distinctly smaller and fainter than the Large Magellanic Cloud, and covers an area roughly 2.5 by 5 degrees in dimension. The overall magnitude is about +2. Since its brightness is spread over about 13 square degrees, it is somewhat harder to find than the Large Magellanic Cloud, and requires darker skies.

View larger The Large Magellanic Clouc is found in the southeast corner of the constellation Tucana. The nearby bright star is Achernar.
View larger The Large Magellanic Cloud is found in the southeast corner of the constellation Tucana. The nearby bright star is Achernar.

Small Magellanic Cloud history

Given its faintness and location far to the south in our sky, the Small Magellanic Cloud wasn’t known in ancient Europe and has no classical mythology associated with it. It does share in the Australian aboriginal tale of Jukara, the old couple who are fed fish from the sky river (Milky Way) by star people. The Small Magellanic Cloud is the camp of the old woman. It’s said that the Large and Small Magellanic Clouds served as important navigation markers to the early Polynesians. The Maori of New Zealand were said to use them as predictors of winds.

Their most famous association in western history came with the expedition of Ferdinand Magellan on his circumnavigation of the world in 1519-1522. The Large and Small Magellanic Clouds became known as the clouds of Magellan after that time. However, later star maps still did not call them that. In Bayer’s Uranometria they are designated as nubecula major and nubecula minor. In the 1756 star map of the French astronomer Lacaille, they are designated as le Grand Nuage and le Petit Nuage (the Large Cloud and the Small Cloud).

Known Milky Way galaxy satellite candidates.  Some may not be true satellites, but may simply be passing near us in space.
Known Milky Way galaxy satellite candidates. Some may not be true satellites, but may simply be passing near us in space. The Large and Small Magellanic Clouds are true satellites of the Milky Way, orbiting around it. Image via Wikimedia Commons

Small Magellanic Cloud science

Although the myths are sparse, the Small Magellanic Cloud holds a very important role in 20th Century astronomy. It was from stars in this galaxy that Henrietta Leavitt deduced the famous “period luminosity” relationship that allowed astronomers for the first time to gauge the distance to star clusters and nearby galaxies.

After the Large Magellanic Clouds, this galaxy is the fourth closest galaxy to the Milky Way. The best current estimate of its distance is about 210,000 light years, or about 30 percent farther than the Large Magellanic Cloud. Classified as a dwarf irregular galaxy, it appears to some as showing indication of a distorted barred spiral structure, likely deformed by the gravitational influence of the Milky Way. Some 15,000 to 17,000 light-years across in the longest dimension, the Small Magellanic Cloud spans nearly 5 degrees of the sky, the equivalent of 9 or 10 full moons. It may contain as many as a few hundred million stars, significantly less than the Large Magellanic Cloud and much less than the Milky Way.

The center of the Large Magellanic Cloud is approximately RA: 0h 52m 45s, dec: -72°49’43”

View larger. | Small Magellanic Cloud and 47 Tucanae by Jonathan Green and Amit Kamble. For more, visit Amit's Facebook page.
View larger. | Small Magellanic Cloud and 47 Tucanae by Jonathan Green and Amit Kamble. Read more about this image.

Bottom line: If you could view the Small Magellanic Cloud with your eye alone – in the sky visible from Earth’s Southern Hemisphere – you would say it does resemble a luminous cloud. Really, though, it is a nearby dwarf galaxy, orbiting our Milky Way.

Read more: Large Magellanic Cloud is spectacular from Earth’s Southern Hemisphere

Posted 
October 31, 2017
 in 
Clusters Nebulae Galaxies

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