During our last advent calendar we celebrated that our community had reached a total of 350,000 people. It’s been an incredible year. Several new projects, lots of fun and many scientific papers later – we expect to reach half a million Zooniverse users in the next day or so. Regardless of exactly when it happens, we want to say thank you to all of you ‘zooites’ out there for continuing to make our projects a big success.

Your feedback, dedication and clicks have really been paying off this year. We’ve seen multiple projects publish their first science results and there are many more on the way in 2012. Next year we expect to launch even more great projects that will allow citizen scientists to assist researchers in even more fields of work, across the world. Watch this space!

In the meantime – what exactly do 500,000 people look like? Wolfram Alpha reports that it’s the number of people who attended Woodstock in 1969. It also says that our community weigh roughly 35,000 metric tons, which is two-thirds the mass of the Titanic. The Zooniverse community generate 35 MW of power when considered as human batteries: that’s enough to supply 10,000 homes! Laid end-to-end 500,000 people stretch roughly 500 miles (~800 km) – which is of course how far the Proclaimers wold have walked.

500,000 people could fill Wembley Stadium 5 times over. Standing side-by-side they could fill the vatican, and there are only 9 armies in the world larger than the Zooniverse (China, USA, India, North Korea, Russia, South Korea, Pakistan, Iran and Turkey). We overtake turkey at 510,000 people – it won’t be long.

UPDATE:

We You did it – our 500,000th citizen scientist was ‘OHMfighter’! Here’s to the next half million! We also wanted to point everyone to their ‘My Project’ pages on the Zooniverse home page, where you can see your classification counts for all our projects. Visit http://zooniverse.org/projects/current to see your stats.

We’re beginning on a new project utiltizing Galaxy Zoo data.

Some background: Active Galactic Nuclei (AGN) are accreting supermassive black holes at the centers of some galaxies. In some of these systems, we observe broad and narrow emission lines in the optical spectra whereas other systems only have narrow emission lines. (In the spectra of normal galaxies that don’t have an active nucleus, we generally don’t see these prominent emission lines. In AGN, photons from the accretion disk photoionize the surrounding gas, causing the emission lines we observe.)

The unified model for AGN explains these observational differences by invoking an obscuring torus (or doughnut) of dust and gas that surrounds the accretion disk feeding the black hole. For a helpful visualization, look here. (Keep in mind that this picture is “zoomed-in” to the center of the galaxy.) If this configuration is aligned so that we’re looking through the opening of the torus, we can see the emission from the accretion disk and gas that’s moving rapidly due to its proximity to the black hole (which causes the broad emission lines in the optical spectra, and the gas from this region is subsequently referred to as the “Broad Line Region”). These sources are classified as Type 1 AGN. If, however, the system is aligned such that the torus is edge-on, that accretion disk and fast moving gas is blocked from our view. We will therefore see emission from gas that is further away from the black hole but close enough to be photionized by accretion disk photons, producing narrow emission lines (and no surprise, this region is called the “Narrow Line Region”). These AGN are Type 2 AGN, sometimes referred to as “obscured AGN” since the central region is hidden from our view.

The hypothesis: These AGN live in galaxies. Are our optical classifications of Type1/Type2 related to the orientation of the host galaxy? Do Type 1 (face-on) AGN preferentially live in face-on galaxies? Do Type 2 (edge-on) AGN tend to inhabit edge-on galaxies? The issue of the alignment of the torus with host galaxy inclination has been studied quite a bit in the past. In local AGN (called Seyfert galaxies), there is a lack of Type 1 systems in edge-on galaxies, but Type 2 AGN seem live in galaxies with any orientation (Keel 1980, Schmitt et al. 1997, Simco et al. 1997, Kinney et al. 2000).

The project: These past studies have been limited to relatively small sample sizes (under 100 galaxies). The Sloan Digital Sky Survey has spectra for hundreds of thousands of objects and Galaxy Zoo has classified thousands of galaxies. Combining these two rich data sets, we can test the above hypothesis with a sample size of several thousand galaxies.

I will blog updates as the project proceeds, so stay tuned to see where this journey takes us!