# What is the difference between LMC and SMC?

Apart from the obvious difference as suggested by their names that the Large Magellanic Cloud is 'larger' than the Small Magellanic Cloud, what are the other differences between them?

Do give all the details you can. Thank you!

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The LMC has an apparent size of about 645x550 arc mins, the SMC 320x205.

Both contain several hundred million stars each. The LMC is about 14000ly in size, and is about 10 billion solar masses; the SMC is 7000ly in size, and is about 7 billion solar masses.

The visual magnitude of the LMC is +0.28, the SMC is +2.23.

Both feature a number of interesting clusters, nebulae, and supernova remnants. Notably, LMC is home to NGC 2070, the Tarantula Nebula, and Supernova 1987A. L The LMC is usually considered an irregular galaxy, though it has a prominent bar, somewhat warped, and a spiral arm. The SMC is a dwarf irregular galaxy, or maybe a barred disc.

LMC is the fourth largest galaxy in our local group, and the third closest to us. SMC is the fifth? largest galaxy in the local group, and the fourth closest to us.

{In a previous version of this response I said: A number of websites proclaim that the LMC and SMC are gravitationally bound to the Milky Way. This has been known to be incorrect since 2007 when Hubble observations showed they are travelling too fast to be orbiting the Milky Way. See also.}

A number of websites proclaim that the LMC and SMC ARE gravitationally bound to the Milky Way. This was based on old information. More recent measurements have challenged this assumption, though further analysis has left open the door for the possibility that the LMC and SMC are gravitationally bound to the Milky Way. We can, however, safely say that the LMC and SMC may be gravitationally bound to the MW.

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More recent work suggests that the LMC may well be gravitationally bound to the MW. I suppose if LMC is bound to MW then probably so is SMC. – Conrad Turner Aug 11 '15 at 9:43
Interesting, thanks for that. I have edited my response accordingly. – Jeremy Aug 12 '15 at 23:05

One of the absolutely fundamental differences between the LMC and SMC, and why they have become among the most studied of astronomical objects, is their metallicity.

The average metallicity of interstellar gas in the LMC is about half that of the Sun, whereas the average metallicity in the SMC is only a fifth that of the Sun. Hence the clouds act as two different, relatively nearby, analogues with which to study what happens to lower metallicity (usually much more distant) galaxies in the early universe, or how metallicity affects things like star formation.

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I think wikipedia is enough.

They are two different satellite galaxies of our Milk Way now, ALTHOUGH maybe they were gravitationally bound before and even now there is a bridge of gas connecting them.

Ferdinand Magellan brought them into common knowledge, although he was not the first people to mention them in writings.

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Wikipedia isn't necessarily enough. The status of the LMC and SMC as satellites of the Milky Way is disputed; see @Jeremy's answer above. – HDE 226868 Aug 5 '14 at 19:16