Strange straight lines

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Those faint, red, straight lines are both cosmic rays – charged particles from space that hit the detector (but not coming from where the camera is pointed). If you click on the map, in the popup menu there is a link called “Single exposures”, which will show you all the individual images that go into making these color images. If you scroll down to the bottom, you’ll see that the last and third-from-last images each have one of these in them. In most of the sky, we can eliminate them when we have multiple exposures, but that’s harder to do when they’re on top of a brighter background like the outskirts of this galaxy.