  Historically, the resolution of optical imaging systems was dictated by
diffraction, and the Rayleigh criterion was long considered an unsurpassable
limit. In superresolution microscopy, this limit is overcome by manipulating
the emission properties of the object. However, in passive imaging, when
sources are uncontrolled, reaching sub-Rayleigh resolution remains a challenge.
Here, we implement a quantum-metrolgy-inspired approach for estimating the
separation between two incoherent sources, achieving a sensitivity five orders
of magnitude beyond the Rayleigh limit. Using a spatial mode demultiplexer, we
examine scenes with bright and faint sources, through intensity measurements in
the Hermite-Gauss basis. Analysing sensitivity and accuracy over an extensive
range of separations, we demonstrate the remarkable effectiveness of
demultiplexing for sub-Rayleigh separation estimation. These results
effectively render the Rayleigh limit obsolete for passive imaging.
