  We present our recent results on the cosmic evolution of the outskirst of
disk galaxies. In particular we focus on disk-like galaxies with stellar disk
truncations. Using UDF, GOODS and SDSS data we show how the position of the
break (i.e. a direct estimator of the size of the stellar disk) evolves with
time since z~1. Our findings agree with an evolution on the radial position of
the break by a factor of 1.3+-0.1 in the last 8 Gyr for galaxies with similar
stellar masses. We also present radial color gradients and how they evolve with
time. At all redshift we find a radial inside-out bluing reaching a minimum at
the position of the break radius, this minimum is followed by a reddening
outwards. Our results constraint several galaxy disk formation models and
favour a scenario where stars are formed inside the break radius and are
relocated in the outskirts of galaxies through secular processes.
