![](\"http:\/\/spaceweekly.com\/wp-content\/uploads\/2020\/03\/A_galactic_traffic_jam_card_full.jpg\")
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The\u00a0barred spiral galaxy\u00a0NGC 3887, seen here as viewed by the\u00a0Wide Field Camera 3\u00a0aboard the\u00a0NASA\/ESA Hubble Space Telescope, lies over 60\u00a0 million light-years away from us in the southern constellation of\u00a0Crater\u00a0(The Cup); it was discovered on 31 December 1785 by the German\/British astronomer\u00a0William Herschel.<\/p>\n
Its orientation to us, while not exactly face-on, allows us to see NGC 3887\u2019s spiral arms and central bulge in detail, making it an ideal target for studying a spiral galaxy\u2019s winding arms and the stars within them.\u00a0<\/p>\n
The very existence of spiral arms was for a long time a problem for astronomers. The arms emanate from a spinning core and should therefore become wound up ever more tightly, causing them to eventually disappear after a (cosmologically) short amount of time. It was only in the 1960s that astronomers came up with the solution to this\u00a0winding problem; rather than behaving like rigid structures, spiral arms are in fact areas of greater density in a galaxy\u2019s disc, with dynamics similar to those of a traffic jam. The density of cars moving through a traffic jam increases at the centre of the jam, where they move more slowly. Spiral arms function in a similar way; as gas and dust move through the density waves they become compressed and linger, before moving out of them again.<\/p>\n