M13: The Great Globular Cluster in Hercules

M13 is one of the most prominent and best known globular clusters. Visible with binoculars
in the constellation of Hercules, M13 is frequently one of the first objects found by curious
sky gazers seeking celestials wonders beyond normal human vision. M13 is a colossal home to
over 100,000 stars, spans over 150 light years across, lies over 20,000 light years distant,
and is over 12 billion years old. At the 1974 dedication of Arecibo Observatory, a radio message
about Earth was sent in the direction of M13. The reason for the low abundance of unusual blue
straggler stars in M13 is currently unknown.