Different features will have different physical causes, but a lot of them occur when the stars and gas in a galaxy are arranged in a flat, rotating disk. Example: the complexities of gravity cause the signature spiral in disks.

I’d say this galaxy is far away but not a record breaker for redshift.

The first question in galaxy Galaxy Zoo is about whether a galaxy’s light is distributed smoothly or not. If not, people get asked about details like spiral arms, bar features, and so on. In this case, people agreed it wasn’t smooth but then weren’t sure about any of the specifics.

I’m not sure if that’s what this specific feature is, but that does occasionally happen! So it’s possible (but rare).

You are right though, that without extra information (like redshift, or obvious visual disturbances to the galaxies) it could be a coincidental line-of-sight overlap!

This is one of the first things Galaxy Zoo ever investigated. The short answer is: it’s 50-50, but something about human psychology/biology makes us more likely to perceive one direction than the other. So your impression is real but it’s internal, not the Universe having a bias. 🔭🧪

This has a processing artifact! The red and blue images were accidentally offset by a few pixels from one another when the colour images were made, and the effect is pretty weird. The volunteers ignored it, so the consensus labels are still good!

The colour images are made by combining images of the same sky at different wavelengths. Redshift is measured from a spectrum (not shown). It’s the shift between where you see a spectral feature and where you expect to see it at rest (if the universe wasn’t expanding this galaxy away from us). 🔭

It’s a less specific label than spiral. The “non-smooth features” could include spiral arms, but there wasn’t enough consensus among the volunteers to confidently apply that label.