What causes this kind of noise?

[FreshFromTheGrave]

So I was attempting to take photos of the moon last night (too hazy - terrible shots) and when looking at the images today I found some really weird stuck pixel looking noise. It's in the same place on each image but only in this specific light, if the shot was under exposed you wouldn't see it and I haven't seen it in any other photos to date.

Is this normal or is there something wrong with certain pixels on my sensor? It's a used 550D so I can't attest as to how it was treated by the former owner. There is some dirt on the sensor which I need to clean off since it shows at small apertures but that comes up as small blurry dark spots.

 

[480sparky]

They're 'hot pixels'.

 

[tirediron]

Looks like 'hot' pixels, a condition caused by the heat generated in the sensor during longer exposures. If they're not showing up during regular exposures it may just be that those particular pixels are a little more subject to earlier over-heating that the rest. I wouldn't worry about it.

 

[pixmedic]

I don't know if i would go so far as to call them "hot"...they are certainly attractive, if you like that sort of thing.

 

[FreshFromTheGrave]

Cool thanks for the replies