Red halos and extragalactic background light
  Deep surface photometry of disk galaxies at optical and near-IR wavelengths
have revealed faint halos with colours much too red to be reconciled with the
resolved stellar populations detected in the halos of the Milky Way or M31.
Alternative scenarios involving high metallicities, nebular emission or large
amounts of dust in these halos are also disfavoured. Here, we argue that
extinction of the optical extragalactic background light in the halos of these
galaxies may possibly be responsible for the reported colour anomalies. We also
discuss how an independent measurement of the optical extragalactic background
light might be accomplished by combining direct star counts with surface
photometry for a single nearby galaxy.
