  At optical wavelengths, Titan's brightness for large Sun-Titan-observer phase
angles significantly exceeds its dayside brightness. The brightening that
occurs near back-illumination is due to moderately large haze particles in the
moon's extended atmosphere that forward-scatter the incident sunlight.
Motivated by this phenomenon, here we investigate the forward scattering from
currently known exoplanets, its diagnostics possibilities, the observational
requirements to resolve it, and potential implications. An analytical
expression is derived for the amount of starlight forward-scattered by an
exponential atmosphere that takes into account the finite angular size of the
star. We use this expression to tentatively estimate how prevalent this
phenomenon may be. Based on numerical calculations that consider exoplanet
visibility, we identify numerous planets with predicted out-of-transit forward
scattering signals of up to tens of parts-per-million provided that aerosols of
$>$1 micron size form over an extended vertical region near the optical radius
level. We propose that the interpretation of available optical phase curves
should be revised to constrain the strength of this phenomenon that might
provide insight into aerosol scale heights and particle sizes. For the
relatively general atmospheres considered here, forward scattering reduces the
transmission-only transit depth by typically less than the equivalent to a
scale height. For short-period exoplanets the finite angular size of the star
severely affects the amount of radiation scattered towards the observer at
mid-transit.
