GalaxyZoo

Dan G.
Dan G.
Joined: 10 Feb 07
Posts: 39
Credit: 97,382
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Topic 193084

All - for pure enjoyment, you all might sign up with www.GalaxyZoo.org. It is a simple and fun public science project to classify galaxies imaged by SDSS. Instead of using computer algorithms, they decided to use human gray matter for pattern recognition purposes. It takes only a few seconds of time to classify one galaxy as either sprial, elliptical, or merger. One guy has done over 140,000. Give it a try.

Cheers,

_dan

agge
agge
Joined: 17 Nov 06
Posts: 19
Credit: 219,951
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GalaxyZoo

I read an article about this in astronomy now, and i was just about to start a thread about it here. It's more than pure enjoyment, because they say it will be used for proper science.

Ernesto Solis
Ernesto Solis
Joined: 11 Jun 05
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I have had a fun time helping


I have had a fun time helping them out!!

Thanks
Ernie

Chipper Q
Chipper Q
Joined: 20 Feb 05
Posts: 1,540
Credit: 708,571
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The Zoo is cool. It's

The Zoo is cool. It's amazing how many galaxies there are, not to mention the many ways they're shaped by gravity...

Speaking of gravity, I was lucky to get this galaxy to classify early on, I guess these are quite rare:


588013382206357664

The dim red blob in the foreground is a galaxy with a redshift of 0.422, so it's quite far away. The galaxy behind it (much farther away) is brighter because the light from it is being focused by a gravitational lens (from all the mass of galaxy in the foreground). You might think that the distortion of the galaxy into a partial ring might be a bad thing, but it's actually a wonderful thing since you can then determine how much mass there is in the galaxy that's doing the lensing. Seems to me if you could detect a specific “shimmer� in the lensed galaxy you could infer (somewhat directly?) things about the stochastic gravitational wave background for the lensing galaxy – does that make sense?

Simplex0
Simplex0
Joined: 1 Sep 05
Posts: 152
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RE: The dim red blob in

Message 72723 in response to message 72722

Quote:

The dim red blob in the foreground is a galaxy with a redshift of 0.422

Does that mean that the wavelength for a given spectra line is 0.422 times longer than it would be for a stationary light sours?

Odysseus
Odysseus
Joined: 17 Dec 05
Posts: 372
Credit: 10,600,835
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RE: Does that mean that the

Message 72724 in response to message 72723

Quote:
Does that mean that the wavelength for a given spectra line is 0.422 times longer than it would be for a stationary light sours?


Yes: in terms of wavelength the redshift z represents the proportional increase. That is, the observed wavelength is 1 + z = 1.422 times the emitted wavelength, while the observed frequency would be 1/(1 + z) = 0.703 times the emitted frequency.

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