“It’s full of stars!”

NGC 346: the brightest star-forming region in the Small Magellanic Cloud (source: ESO)
NGC 346 (source: ESO) – click for a larger view

Over two hundred thousand light years away, in the constellation of Tucana (the Toucan), the young star cluster NGC 346 is like many others. With images of such astronomical phenomena you see a relative concentration of points of light, and possibly a wispy nebular of gas and dust. The pictures are often pretty, and some may even be described as dramatic. But what impresses me most about images of star fields is the sense of scale and perspective they can impart.

The computer on which I write is an Apple Mac. One of the features of Apple’s OS X operating system is a backup program that takes historical snapshots of the system, and the user interface to this so-called “Time Machine” is a field of stars that move out of the screen toward the viewer. The effect is an example of “eye candy”, and to my mind it is rather tacky.

Look at a static image of real stars, however, and the power of imagination alone can set the mind roving through the field. With a large enough picture of stars in front of me, I feel myself sucked into the image, and this can be an exhilarating experience.

The Small Magellanic Cloud within which NGC 346 is located may be no more than a tiny satellite galaxy of our Milky Way, but the distances involved are nonetheless vast. To put matters in stark if not ludicrous perspective, NGC 346 is around 200 light years across, or nearly two million billion kilometres. This is roughly equivalent to seven thousand billion times the length of Wales, or fifty times the distance between the Sun and its nearest stellar neighbours.