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We use classifications provided by citizen scientists though Galaxy Zoo toinvestigate the correlation between bulge size and arm winding in spiralgalaxies. Whilst the traditional spiral sequence is based on a combination ofboth measures, and is supposed to favour arm winding where disagreement exists,we demonstrate that, in modern usage, the spiral classifications Sa-Sd arepredominantly based on bulge size, with no reference to spiral arms.Furthermore, in a volume limited sample of galaxies with both automated andvisual measures of bulge prominence and spiral arm tightness, there is at besta weak correlation between the two. Galaxies with small bulges have a widerange of arm winding, while those with larger bulges favour tighter arms. Thisobservation, interpreted as revealing a variable winding speed as a function ofbulge size, may be providing evidence that the majority of spiral arms are notstatic density waves, but rather wind-up over time. This suggests the "windingproblem" could be solved by the constant reforming of spiral arms, rather thanneeding a static density wave. We further observe that galaxies exhibitingstrong bars tend have more loosely wound arms at a given bulge size thanunbarred spirals. This observations suggests that the presence of a bar mayslow the winding speed of spirals, and may also drive other processes (such asdensity waves) which generate spiral arms. It is remarkable that after over 170years of observations of spiral arms in galaxies our understanding of themremains incomplete.

Galaxy Zoo: Unwinding the Winding Problem - Observations of Spiral Bulge Prominence and Arm Pitch Angles Suggest Local Spiral Galaxies are Winding