Typical short-exposure image of a binary star (ζ Boötis) as seen through atmospheric turbulence. Each star should appear as a single point, but the atmosphere causes the images of the two stars to break up into two patterns of speckles. The speckles move around rapidly, so that each star appears as a single fuzzy blob in long exposure images.Slow-motion speckle imaging movie, showing how a high-magnification (negative) image of a star breaks up into multiple blobs (speckles), entirely an atmospheric effect.
Speckle imaging comprises a range of high-resolution astronomical imaging techniques based on the analysis of large numbers of short exposures that freeze the variation of atmospheric turbulence. They can be divided into the shift-and-add ("image stacking") method and the speckle interferometry methods. These techniques can dramatically increase the resolution of ground-based telescopes, but are limited to bright targets.
