KentuckyFC writes "The structure of the Milky Way is notoriously difficult to work out because we see our galaxy edge on. That means nearer clouds and stars are superimposed on more distant ones and telling them apart is hard. However, astronomers have unveiled a new map based on velocity measurements made on 870 clouds of carbon monosulphide. This has revealed a number of new features of the Milky Way including a previously unknown spiral arm, some 30,000 light years from the galactic core. But the most surprising finding is that some of our galaxy's spiral arms are straight rather than curved, giving the Milky Way a distinctly square look. That's not quite as outrageous as it sounds. Astronomers know of a number of other galaxies with straight arms, such as the pinwheel galaxy M101. So ours probably looks something like this."