Hurricane Ivan from the Space Station (APOD 13 Jan 08)

marion ballantyne · Post by **marion ballantyne** » Sun Jan 13, 2008 2:12 pm

Can similarities be drawn between hurricanes and galaxies? Their shape is much the same, and both have the point of greatest rotational force within the Eye and the Black Hole.
Marion

craterchains · Post by **craterchains** » Sun Jan 13, 2008 3:53 pm

Simply stated, yes.

Pete · Post by **Pete** » Sun Jan 13, 2008 5:55 pm

Feeling eloquent today?

Both spiral galaxies and hurricanes form "logarithmic spirals," as do many other natural structures. At any point in a log spiral, the tangent line of an arm makes a constant angle with the radial line passing through the tangent point.

Do any readers have insight about precisely why hurricanes and spiral galaxies take on (approximately) log spiral shapes in particular?

The following APOD compares a hurricane with a galaxy:
http://antwrp.gsfc.nasa.gov/apod/ap030925.html

craterchains · Post by **craterchains** » Mon Jan 14, 2008 5:18 am

Do any readers have insight about precisely why hurricanes and spiral galaxies take on (approximately) log spiral shapes in particular?

Yes, simply stated, resistance.