Magellan got the credit, but Vespucci wrote about this galaxy first
In a letter from 1502, Amerigo Vespucci described three Canopi in the southern sky, two bright and one dark. The bright pair were the Magellanic Clouds, satellite galaxies of the Milky Way. Ferdinand Magellan saw them seventeen years later, and because his voyage's writings spread widely, his name stuck to both.
The Large Magellanic Cloud sits about 163,000 light-years away, making it the second or third nearest galaxy to ours. To the naked eye from a dark southern site it looks like a detached smudge of Milky Way stretching about 10 degrees, some 20 times the Moon's width, across the constellations Dorado and Mensa. From most of Australia and South Africa it never sets. A claim that the Persian astronomer al-Sufi recorded it around 964 as the White Ox seems to rest on a misreading of a passage about stars he admitted never seeing.
It is roughly 32,000 light-years across with about a hundredth of the Milky Way's mass, the fourth largest galaxy in the Local Group. Its off-centre bar hints that it was once a barred spiral whose arms were torn up by the Small Magellanic Cloud and our own galaxy's gravity. A bridge of gas links the two Clouds, and they share an envelope of hydrogen, signs of a long partnership. The disc is tilted about 35 degrees and rotates once every 250 million years. In roughly 2.4 billion years it is expected to merge with the Milky Way.
Astronomer Robert Burnham Jr. called it a great celestial laboratory. Surveys have tallied roughly 700 open clusters, 400 planetary nebulae and 60 globular clusters. It hosts the Tarantula Nebula, the Local Group's busiest stellar nursery, and supernova 1987A, the nearest seen in recent times. Australian astronomers named one nitrogen-rich supernova remnant after High Court judge Lionel Murphy, partly for his love of science and partly for its supposed likeness to his large nose.
A heavy black hole, perhaps 600,000 solar masses, appears to lurk at its centre, and 21 fast-moving stars in our galaxy's halo may have been flung out by it. Cepheid stars there anchor the cosmic distance ladder; a 2013 study using eclipsing binaries pinned the distance with 2.2 percent accuracy.
Source: Large Magellanic Cloud
