The Magellanic Clouds, our galactic neighbors


The evening sky from ESO’s Paranal Observatory in Chile, with the Large and Small Magellanic Clouds showcased at middle. Image by way of Y. Beletsky/ LCO/ ESO.

Lucky Southern Hemisphere observers get to see one thing that many northerners by no means see: the Magellanic Clouds. The Large and Small Magellanic Clouds are satellite galaxies of the Milky Way. As a number of the closest galaxies to our house galaxy, they stand out as large, misty blobs of sunshine beneath darkish skies. Scientists estimate the Small Magellanic Cloud accommodates round 3 billion stars, whereas the Large Magellanic Cloud homes some 30 billion stars.

History normally credit Fifteenth-century Portuguese voyager/astronomer Ferdinand Magellan with “discovering” these hazy star-clouds. And, in later years, the Clouds grew to become identified by his title. But, along with Magellan, many early navigators used these two small galaxies to seek out their approach throughout southern oceans. And they had been all the time noticeable within the sky to the individuals of the Southern Hemisphere, and they also figured in early southern legends and myths.

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The Magellanic Clouds from the Southern Hemisphere

If you wish to see the Magellanic Clouds, you must head south. They’re not seen north of about 17 degrees north latitude. If you’re within the Southern Hemisphere, you may see these satellite galaxies any evening of the 12 months as a result of they’re south circumpolar, that’s, they’re shut sufficient to the South Celestial Pole that they by no means set.

The Large Magellanic Cloud is among the closest galaxies to us at about 160,000 light-years away. It’s about 40,000 light-years nearer than the Small Magellanic Cloud.

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How to see the Magellanic Clouds

The Large Magellanic Cloud is simpler to identify than the Small Magellanic Cloud, however they each require dark skies.

The Large Magellanic Cloud shines at magnitude 0.9. Keep in thoughts that it’s stretched out over an space of sky about 9 by 11 degrees. A star of that magnitude would seem very shiny due to its pinpoint supply of sunshine, however for the Large Magellanic Cloud, its diffuse, spread-out gentle means it seems as a hazy smudge on the sky.

The Large Magellanic Cloud lies in each the constellations Dorado and Mensa. Draw a line from Sirius previous the suitable aspect of Canopus to seek out it.

Star chart with stars in black on white, with one very large star.
The Large Magellanic Cloud is discovered within the constellations Dorado and Mensa. The close by star is Canopus. Image by way of Wikipedia.

The Small Magellanic Clouds shines at magnitude +2. Its brightness is unfold over about about 13 sq. levels of sky. You can discover it within the southeast nook of the constellation Tucana the Toucan.

Sky chart showing the constellation Tucana and the Small Magellanic Cloud.
Tucana the Toucan is a well-known constellation for being house to 2 superb deep-sky objects that may be seen with out optical assist: the Small Magellanic Cloud and the globular cluster 47 Tucanae.

The Clouds in fable

In the Southern Hemisphere, Australian Aborigines, the Maori individuals of New Zealand and the Polynesian individuals of the South Pacific had been conversant in each the Large and Small Clouds. They used them as navigational markers throughout their oceanic expeditions. They thought-about these hazy star-clouds predictors of the winds. The web site explains:

Many tribes of Australian Aboriginals have ‘dreamtime stories,’ which they’ve handed down from era to era, to elucidate the universe as they understand it. One such legend describes the Clouds because the campfires of an previous couple, the Jukara. The Jukara relied on different star individuals to produce them with fish and lily bulbs caught within the Milky Way to outlive. The previous couple cooked the meals over their campfire, which was the star Achernar. The Large Cloud represented the previous man whereas the Small Cloud was the previous lady.

Another fable comes from South Africa. The close by constellation Mensa (“Table”) acquired its title from South Africa’s Table Mountain. One story says that the Large Magellanic Cloud is a puff of smoke from a pipe-smoking contest held on the mountain.

In historical past, Al Sufi, the Persian astronomer, described the Large Magellanic Cloud in his Book of Fixed Stars in AD 964. He referred to as it Al Bakr, describing it because the White Ox of southern Arabia.

Desert landscape with road and car lights, arching Milky Way above with bright patch under.
View larger. | In this picture from Paranal, Chile, you may see the big swath of our galaxy, the Milky Way. The dwarf satellite galaxy, the Large Magellanic Cloud, is beneath the arch. The Small Magellanic Cloud is to its higher proper. Image by way of Yuri Beletsky/ ESO.

Science of the Magellanic Clouds

Henrietta Swan Leavitt – well-known for her work on the Cepheid variable stars – studied the Large and Small Magellanic Clouds from Harvard College Observatory in Southern Peru. In the early 1900s, she revealed her work on variable stars within the Small Magellanic Cloud, famously displaying the connection between the durations (cycles) of the celebrities’ variability and their luminosities. Her examine was titled 1777 variables within the Magellanic Clouds. The period-luminosity relationship later grew to become a dependable gauge for astronomers attempting to parse the riddle of star and galaxy distances.

Astronomers imagine that the Large and Small Clouds fashioned across the identical time as our Milky Way, some 12 to 13 billion years in the past. Due to their repeated interplay with our bigger Milky Way galaxy, it’s thought that nice galactic tides may need precipitated their irregular form.

The ongoing Dark Energy Survey discovered a darkish stream of interacting matter between the Large and Small Magellanic Clouds. Simulations carried out by a group of scientists on the University of Arizona recommended that the 2 galaxies is likely to be interacting with one another and would possibly finally merge.

Whitish-blue oval in upper right and smaller oval of light at lower left in starfield.
The Large and Small Magellanic Clouds are irregular galaxies that belong to the Local Group. Image by way of ESO/ S. Brunier.

Bottom line: The Large and Small Magellanic Clouds are two of the closest galaxies to the Milky Way. They could be seen with out optical assist from southern skies.

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