Map 22: South Polar 1
Eridanus to Centaurus
August 23, 2007
This map contains two spectacular objects — the Large Magellanic Cloud (LMC) in Dorado and the Small Magellanic Cloud (SMC) in Tucana. They received their names because one of the first Northern Hemisphere inhabitants to describe the clouds was Portuguese explorer Ferdinand Magellan in 1519, during his circumnavigation of the world.
These objects are not earthbound clouds, however, but satellite galaxies of the Milky Way. The LMC lies 170,000 light-years away, and the SMC is 210,000 light-years distant.
Magnitudes for such extended objects don't mean much, but the LMC shines at approximately 0 magnitude. So, if you took the light from Vega (Alpha Lyrae) and spread it out over an area equal to that of the LMC, it would look about the same. The SMC glows at magnitude 2.3.
The full extent of these galaxies is large. The LMC occupies an area roughly 11° by 9°. Nearly 400 Full Moons would be needed to cover that much sky. The SMC covers a smaller, but still impressive, area — 4.5° by 2.5° (45 Full Moons).
Although the LMC and SMC are small irregular galaxies, many celestial objects within and around them are worth pulling out a telescope for. In the LMC, for example, a star-forming region of glowing hydrogen known as the Tarantula Nebula (NGC 2070) provides an easy target for telescopes of all sizes.
Near the SMC (but belonging to the Milky Way) is the brilliant globular cluster 47 Tucanae (NGC 104). This 4th-magnitude object lies 13,400 light-years from Earth and covers approximately the same amount of sky as the Full Moon — ½°.
But the Tarantula Nebula and 47 Tucanae are just the beginning. The NGC and IC catalogs tally nearly 400 objects in the LMC and 37 in the SMC. To see many of them, you'll need a big telescope, and you'll have to use high magnification. But even through a small telescope or binoculars, these two galaxies will fascinate you.
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