Boundaries of the Universe

10. The Galaxies

 

One of the great revelations in astronomy during the present century is undoubtedly the discovery that beyond the Milky Way, beyond the globular clusters which form a gigantic halo around the nucleus of our own Galaxy of a hundred thousand million stars, there exist other galaxies, many of which are comparable in size and structure to ours. A mere handful of these are visible to the naked eye and were known to the ancients. The Andromeda nebula, for example, was classed as a star by Al Sufi in 964 and, although there are no written records available, the two Magellanic Clouds must also have been known to the inhabitants of the Southern Hemisphere long before they were discovered by the first European explorers.

With the invention ...