That's spectacular. We think we know a lot about our own galaxy and then structures that size are discovered. It's also interesting that the discovery was made using publically available data. It must encourage amateur sleuths.
Wow, that is interesting. It's huge, would love to know what created it. One thing I don't understand though is they say it could be up to a million years old. But if gamma and x-rays travel at c then wouldn't it only be 25,000yrs old ?
Craig, I think you are confusing the gamma rays with the material that is emitting them. If the diagram is to scale (I don't think it is) then the gamma rays from the nearest part of the structures would be about 10,000 years old (ie been travelling for 10,000y) and from the furthest parts perhaps 30,000y. If the structure is formed by some sort of explosion/outflow then its age = size/expansion rate. Reading between the lines I don't think they have the expansion rate. I don't know whether one can determine velocity from doppler shift using gamma rays. We may have to wait until it is detected in other parts of the spectrum.
