  Massive stars live short lives, losing large amounts of mass through their
stellar wind. Their mass is a key factor determining how and when they explode
as supernovae, enriching the interstellar medium with heavy elements and dust.
During the red supergiant phase, mass-loss rates increase prodigiously, but the
driving mechanism has proven elusive. Here we present high-contrast optical
polarimetric-imaging observations of the extreme red supergiant VY Canis
Majoris and its clumpy, dusty, mass-loss envelope, using the new
extreme-adaptive-optics instrument SPHERE at the VLT. These observations allow
us to make the first direct and unambiguous detection of submicron dust grains
in the ejecta; we derive an average grain radius $\sim$ 0.5 $\mu$m, 50 times
larger than in the diffuse ISM, large enough to receive significant radiation
pressure by photon scattering. We find evidence for varying grain sizes
throughout the ejecta, highlighting the dynamical nature of the envelope.
Grains with 0.5 $\mu$m sizes are likely to reach a safe distance from the
eventual explosion of VY Canis Majoris; hence it may inject upwards of
10$^{-2}$ M$_\odot$ of dust into the ISM.
