Billions and billions of stars and star systems in the form of constellations, galaxies, binary and eclipsing binary star systems, a variety of clusters (open, globular etc) as well as supernova remnants and emission, reflection and planetary nebulae characterize this universe once we go past the solar system. Aside from our sun which represents are closest star, distances start to be measured in light-years when describing our next closest star, cluster, galaxy etc.

Globular star clusters are a symmetrical collection of ancient stars (up to a million such stars) which are bound together gravitationally. Recent estimates indicate that about 150-200 globulars exist throughout our galaxy with only three being readily visible to the naked eye. Since most of the globular clusters are more common in the southern hemisphere, scientists have deduced that our sun must lie away from the galactic core of the Milky Way. One of the most beautiful such globular clusters is M13 in Hercules.

In contrast, open star clusters are widely distributed in our galaxy and represent a loose collection of stars which number from a few dozen to a few hundred stars and are weakly-held gravitationally. Perhaps the three most famous such open clusters are the Pleiades (M45) in Taurus, the Beehive (M44) in Cancer and the double cluster in Perseus. They are all characterized with a handful of hot and white prominent stars and nebular material surrounding these stars.

Note: For an excellent article on globular star clusters, see Astronomy Magazine (Apr/2008: 58-61, Sep/2008: 12-13).