Open star clusters are groups of stars in loosely-bound gravitational associations. The stars are further apart than the stars in their cousins, the globular clusters. The weak gravity from the loose clusters means open clusters take on irregular shapes. They usually contain only a few thousand stars. The... read full story
Photo: This whole collection is NGC 1858, an open star cluster in the northwest region of the Large Magellanic Cloud, a satellite galaxy of our Milky Way that boasts an abundance of star-forming regions. NGC 1858 is estimated to be around 10 million years old.