IC 438

A barred spiral galaxy in the constellation of Lepus, the Hare. IC 438 falls approximately halfway between Arneb, the brightest star in Lepus, and brilliant Sirius in Canis Major to the east. At twelfth magnitude, IC 438 is extremely faint, but can be resolved to show an intricate spiral pattern with two distinct arms winding round each other as they extend from the core of the galaxy. These arms are not perfectly symmetrical, and the eastern arm extends noticeably farther from the nucleus than its western counterpart.

In the sky, IC 438 lies close to another galaxy of apparently similar size and structure, IC 2151. In fact the two are unrelated, and appear close to another due only to a line-of-sight effect. IC 2151 is 102 million light years from our own Milky Way Galaxy, but IC 438 is even farther away, at a distance of 144 million light years. Knowing this distance, and its apparent dimensions in the sky, allows us to calculate the diameter of the galaxy: IC 438 is approximately 100,000 light years from edge to edge, a size closely comparable to our own Galaxy.

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