The Rise and Fall of Galactic Cities

JPL Press Release…

In the fable of the town and country mice, the country mouse visits his city-dwelling cousin to discover a world of opulence. In the early cosmos, billions of years ago, galaxies resided in the equivalent of urban or country environments. Those that dwelled in crowded areas called clusters also experienced a kind of opulence, with lots of cold gas, or fuel, for making stars.

Today, however, these galactic metropolises are ghost towns, populated by galaxies that can no longer form stars. How did they get this way and when did the fall of galactic cities occur?

A new study from NASA’s Spitzer Space Telescope finds evidence that these urban galaxies, or those that grew up in clusters, dramatically ceased their star-making ways about 9 billion years ago (our universe is 13.8 billion years old). These galactic metropolises either consumed or lost their fuel. Galaxies in the countryside, by contrast, are still actively forming stars.

“We know the cluster galaxies we see around us today are basically dead, but how did they get that way?” wondered Mark Brodwin of the University of Missouri-Kansas City, lead author of this paper, published in the Astrophysical Journal. “In this study, we addressed this question by observing the last major growth spurt of galaxy clusters, which happened billions of years ago.”

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Postcard from the Reef – Scorpion

I have found these fish in the daytime, usually deep inside a cauliflower coral and nearly impossible to photograph. By night they emerge to hunt. As with most scorpionfish, they are ambush hunters, sitting on the bottom and waiting for some hapless critter to come too close. Of course the habit of sitting still makes them ideal targets for a camera, they hold their ground even when the strobe goes off.

Cheekspot Scorpionfish
A cheekspot scorpionfish (Scorpaenodes littoralis) near the shore in 4′ of water, Mahukona

Casino Night Photography

Last night was the company Christmas party. We did something different this year, a casino night. A full set of dealers and tables awaited us at the Mauna Lani clubhouse for the evening. Signing in at the door everyone received a stack of play money and the fun began.

It was fun in two ways… Playing the games! Everyone seemed to have a great time, particularly with no real money at stake. I noted that we were all quite conservative at the start, as the evening progressed the bets became risky and the money began to really fly about.

It was also fun because I thought to bring the new camera. I know of no real casino that would let me take pictures of the games like this. Alas, this was not real. There was the added advantage that everyone knows me and knows how I use the camera. I did get good photos of more than a few people. Photos I will have to process up and distribute over the next few days.

A full frame camera with a fast lens was just what was needed for the evening. I only brought the one lens… A 50mm f/1.8 prime, the nifty fifty. It turned out to be the perfect lens for the evening. The lighting was dim, to be expected, but it was also very hard. Small quartz spots illuminated most of the gaming tables resulting in bright areas and dark backgrounds.

To the hard lighting I added the very shallow depth-of-field that comes with a fast lens and large sensor camera. The result was perfect, very moody shots of the game with fantastic bokeh…

Fatal or Not

I had never before seen one on the reef, but I knew what it was immediately…

This thing could kill me!

It is odd to look at something so small and pretty and realize that it could be fatal to touch. There are three cone snails that feature a potentially lethal venom found on Hawaiian reefs, the textile cone (Conus textile), the banded marble cone (Conus bandanus), and the striated cone (Conus striatus oahuensis). All three feature similar markings, a sort of chevron pattern on the shell. I did not recall which one of the three I was looking at, but I knew it was one of them.

Then I see the legs.

Small red and yellow legs protrude from the shell, just barely visible underneath. No problem, the deadly snail is gone and something else has moved into the pretty shell. A hermit crab, appropriately enough a cone shell hermit crab.

With little to fear from a hermit crab I set the shell just so on the coral. I know that the crab will wait a few moments then emerge to right his shell, providing a perfect photo opportunity…

Cone Shell Hermit Crab
Cone shell hermit crab (Ciliopagurus strigatus) occupying the shell of a textile cone snail (Conus textile)