Emergence in Astronomy

What happens when astronomers have too much data to sift through? They put it in a Galaxy Zoo.

When you (read: anyone) register to Galaxy Zoo, you can browse through pictures from the Sloan Digital Sky Survey (SDSS) and classify individual galaxy types: spiral, elliptical or merging, and the orientation: clockwise or counter-clockwise. So if you're an accountant on your lunch break, why not classify some galaxies in your free time? If you're browsing the internet on your iPhone - classify some galaxies. You might even discover something interesting and end up with your name on it - like Hanny's Voorwerp.

The universe is so mind-boggingly huge that thousands of galaxies can be observed in a tiny swatch of sky. To get a sense of this, extend your arm directly in front of you and hold up your pinky finger. At one arm length, the width of your smallest finger covers about one degree in the sky. The Hubble Ultra Deep Field, shown above, covers about 1% of the area on your pinky nail and contains an estimated 10,000 galaxies. SDSS works on imaging about 25% of the sky - covering an area about 100,000 times the size of the Hubble Ultra Deep Field! It's called ultra deep for a reason; SDSS will not be collecting enough light to peer that deep into the sky. However, it is estimated that at least one million galaxies will be imaged by Sloan.

What a great time to harness the collective power of the internet. Galaxy Zoo recruits people, no matter what profession or creed, to participate in science. The website describes some of the motivation behind this. For me, this process is intriguing with respect to Emergence.* One example of emergence is the curious ability for a large group of people, making individual guesses, to arrive at an average answer that is very close to the precise answer - even when there was no collaboration or discussion among them. Galaxies are not the easiest artifacts to classify. With nondescript distant fuzz balls, how close can you really get? Physical orientation, gravitational lensing, and the simple tendency of nature to defy thin-lined classification schemes can all pose a problem. The most exciting thing is that the powers of emergence can help us move forward in exploring the universe. When you click on a galaxy classification, the scientists don't know the answers beforehand. We have only to trust in the power of emergence to find something close to the truth.

On a lighter note, check out the Galaxy Zoo Blog. According to the project leaders:

At last count, Galaxy Zoo had 141,960 volunteers. Here are some other things that we are bigger than:

- The entire nation of St. Vincent and the Grenadines
- Chris’s hometown, twice over
- The entire student population of the Universities of Michigan, Illinois, and Texas, combined
- The Italian Army
- …and 30 American Astronomical Societies.

* Refer to the Emergence episode of Radiolab I mentioned in an earlier post