Astronomy Picture of the Day . ... Flowing Barchan Sand Dunes on Mars . ... The View Near a Black Hole . ... Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes. ... Discovered by accident, this manuscript page provides graphical insight to astronomy in medieval times, before the Renaissance and the influence of Nicolaus Copernicus, Tycho de Brahe, Johannes Kepler, and Galileo. ... Castle and Full Moon . ...