The new year has begun with a peculiar solar event – a huge hole becoming visible close to the Sun’s south pole. NASA astronomers have released images taken from their Solar Dynamics Observatory which show a spectacular ‘coronal hole’ which appeared on January 1. The ‘hole’, which appears on the images as a darker area, measuring hundreds of miles across, is caused by the magnetic field reaching out into space rather than looping back on to the solar surface.
Where the particles leave the sun the surface appears much darker than the rest of the corona. Scientists from the observatory used the highly technical Atmospheric Imaging Assembly (AIA) instrument to record the pictures. The particles moving outward are carried on a ‘solar wind’ which can travel at up to 500 miles per hour. Coronal holes can be visible for up to five years but can shift shape according to the prevailing conditions. Late last year Nasa’s Nuclear Spectroscopic Telescope Array, or NuSTAR, took pictures for the first time using high-energy X-rays. NuSTAR was designed to look at black holes and other stellar phenomena.
Source : AFP