cyclones

As hurricane Sandy smashed over the Caribbean and into the east coast of North America, I worried for my friends. And I thought of superstructures. Swirling, spiral structures, above the surface of our blue planet.

The October spinning storm caused unprecedented damage including substantial flooding in New York City. Eleven states plus DC were declared disaster areas. 20 000 flights were cancelled. More than 100 people were killed. Not as intense as Typhoon Tip in 1979, thank goodness. Not the deadliest tropical storm.

Cyclonic storms can be very small, the size of a city. They can be very large, covering much of a continent. Considering the damage typically caused, the associated loss of animal and human life, it is difficult to think of them as microscopic.

I've experienced a number of hurricanes. All from afar. Astonishing waves on Lake Huron when I was in high school. The outflow cirrus shield visible in the south a couple of summers back. Trees down in High Park, a sudden snow storm in Georgian Bay, a gas shortage in the GTA from Sandy. Every time, I am awestruck by the raw power. I know I'm hundreds of kilometres from the centre. What must it be like near the eye.

And so too, in the "eye" of a spiral galaxy, where it is generally considered that black holes live. Sometimes one. Sometimes several. Large. Or very large. And it is also well understood that black holes absorb. In and of themselves they do not emit. They pull in material. And once in their grasp, nothing can escape. Once caught in the gravity, in that final spiral, one's fate is sealed. We're starting to record details of material and stars in the centre of galaxies being crushed, stretched, flung about, smashed, and torn apart. A maelstrom.

The mechanics of a tropical cyclone is very different than what is going on in a macroscopic spiral galaxy to be sure. That becomes very apparent when you consider the vertical structure of a cyclone. But when you view them both from the "top," above their centres, the similarities are eerie. A huge, rotating, flat disk. Arms, curving outwards, harboring isolated regions of activity, small storms, tornadoes, death, destruction, soon to be regions of rebirth and growth, produced through powerful waves.

Creds:

• Messier 74 from the Hubble Space Telescope
• hurricane Sandy captured by the NOAA GOES-13 satellite