Logarithmic Spirals Isabel and M51

Explanation: Uncomfortably close hurricane Isabel (left) and 30 million light-year distant galaxy M51 actually don't have much in common. For starters, Isabel was hundreds of miles across, while M51 (the Whirlpool Galaxy ) spans about 50,000 light-years making them vastly dissimilar in scale, not to mention the extremely different physical interactions which control their formation and evolution . But they do look amazingly alike, both exhibiting the shape of a simple and beautiful mathematical curve known as a logarithmic spiral , a spiral whose separation grows in a geometric way with increasing distance from the center. Also known as the equiangular spiral , growth spiral, and Bernoulli's spiral or spira mirabilis , this curve's rich properties have fascinated mathematicians since its discovery by 17th century philosopher Descartes . Intriguingly, this abstract shape is much more abundant in nature than suggested by the striking visual comparison above. Logarithmic spirals also describe, for example, the arrangement of sunflower seeds , the shapes of nautilus shells, and ... cauliflower .