Physics Photo of the Week

  In April, 2022, winter does not want to "give-up".  Many folks at Warren Wilson College noticed this "wintry mix" on April 9, 2022.  This wintry precipitation resembles Styrofoam beads, but on close inspection these "beads" are icy and some have melted to form liquid water.  Many said that they resembled hail because they consist of ice.  They are not hail - hail is formed by the strong convection updrafts in thunderstorms that form only in the summer season.  Graupel forms in a winter snowstorm under special conditions that only form in the winter.  Graupel is actually a form of sleet.   The graupel "beads" actually began as snow flakes from a snow forming cloud.  A snow-forming cloud requires a dew point within the cloud that is below the freezing point (0 deg C or 32 deg F).  The moisture in the cloud sublimates directly from the solid into frozen snow crystals.  As more of the snow crystals form, they fall randomly and of...

  The Crab Nebula - M1 in the Messier Catalog has been a popular item for the College View Observatory and Physics Photo of the Week.  This color photo required about 3 night sessions spread over 2-3 weeks last month obtaining and stacking many images through the different colored filters in order to create this color photograph. The Crab Nebula is the expanding remnant of a supermassive stellar explosion of a massive star dying.  The large progenitor star suddenly ran out of nuclear fuel and suddenly collapsed as a massive implosion.  A stellar implosion doesn't merely cause the star to disappear, but actually causes a massive rebound scattering the outer layers of the star far out into space.  This seems counter-intuitive.  How can an implosion cause a massive ex plosion? The answer may be explained by a simple demonstration that I used to do for physics and astronomy classes with a golf ball and ping pong ball.  In this experiment I would hold both ...