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Sunday, August 5, 2007

On Exploration, Or, Be An Astronomer In The Privacy Of Your Own Home

I love to explore.
I’m the kind of person who loves to take a new road, or hear a new song, or consider a point of view different than my own.

It leads me to read a lot of foreign blogs, as well, and that’s how we get to today’s story.

I’m a member of the Blogpower community of bloggers, the majority of whom are located in countries of the British Commonwealth, including Onyx Stone, who blogs from the UK; and it was in the course of visiting his blog that I found a story of do-it-yourself space exploration that deserves to be retold.

The Sloan Digital Sky Survey, in their own words, “ the most ambitious astronomical survey ever undertaken.” The goal is to gather image data which will be used to create a 3-D map of about a quarter of the sky. It’s estimated that when complete the map will include about a million galaxies and quasars.

Sloan reports the first phase (SDSS-I) of the project, completed in 2005, gathered data on over 200 million objects-including 675,000 galaxies and 90,000 quasars. Phase two (SDSS-II, but I bet you saw that coming), underway until 2008, has expanded into a three-part project with 25 institutional partners, including The University of Chicago, The United States Naval Observatory, a Japanese consortium, Oxford University, and the University of Washington.

The primary instrument used to gather the images is a 2.5 meter telescope located in the city of (irony alert!) Sunspot, New Mexico at the Apache Point Observatory and operated by the Astrophysical Research Consortium in cooperation with the University of New Mexico.

Here’s the big question that was being pursued:

If the Big Bang theory is correct, you would expect matter to be more or less evenly distributed throughout the known universe-but that’s not the case. Matter is clustered together in groups, with large “void” areas that have no visible matter. So why didn’t matter distribute itself evenly?

What else might be learned from the survey?
Here’s a stunner:

Our own galaxy, the Milky Way, appears to be colliding with another, smaller galaxy located “near” the constellation Virgo-and that galaxy may be one of several that appear to be in the process of being absorbed into our own.

Here’s another:

The Milky Way may be surrounded by a ring of stars left over from a previous encounter, much as Saturn is surrounded by rings. (Here’s an example of another galaxy surrounded by a ring.)


The vast majority of the mass of the Milky Way is invisible to our current detection tools, and is currently inferred to exist as a “halo” of an unknown type of matter that surrounds our galaxy, and perhaps other potential formations within the galaxy. This is the current incarnation of “dark matter” thinking; and getting to the bottom of this mystery is a sort of astrophysical Holy Grail. It is hoped that SDSS-I and –II will provide more data that can lead to better answers to this most fundamental “who are we and what surrounds us?” question.

Now here’s the good part.

Uncle Astronomer wants you.

It turns out humans are better than computers at identifying types of galaxies based on the existing digital images, and there are so many images to classify that outside help is needed.

A special website,, has been created to facilitate the process.
How does it work?
I’m glad you asked.

After registering with GalaxyZoo, you are given a tutorial that teaches you to identify a spiral from an elliptical galaxy and other basic facts. You’re then given a simple test (I promise, no need for test anxiety on this one), and after that, you start evaluating images of actual unclassified galaxies, stars, and other objects.

I’ve done it myself, and it can take anywhere from a few seconds to a few minutes to classify a galaxy; and before you know it you’ve done 10, and then 100.

Anyone reading this a parent?
This is a great project for a kid who has an interest in the sky, and all of the content is extremely “G rated”.

It’s this process, multiplied times all of you, that astronomers hope will allow them to make faster progress through this mountain of data (10 terrabytes so far, released in annual increments. The 6th data release-DR6-home page is here).

So that’s our Sunday “day off from politics” story-advanced astronomy is now a living room endeavor, and you-and the kids-are invited to help make science history.

Did you ever want to be an amateur astronomer, and have fun doing it?
Head over to GalaxyZoo and give it a shot.

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