13,000,000,000 BBY, or 13,000,000,000 Before the Battle of Yavin, was the approximate year in which scientists believed that the galaxy was formed from dust and gas. Star systems and planets would form in the following eons within the galaxy, and life and sentience eventually emerged on a portion of those worlds, leading to the events of the galactic history.
The galaxy that was formed in 13,000,000,000 BBY
13,000,000,000 BBY, or 13,000,000,000 Before the Battle of Yavin, was a year of the Galactic Standard Calendar that fell within the Pre-Republic era. By that year, the universe had already been created as a result of the event known as the Big Bang. Many scientists later believed that, around 13,000,000,000 BBY, a cloud of dust and gas one hundred thousand light-years across experienced a gravitic collapse. Eventually, the cloud coalesced to form a disk of the same dimensions—the galaxy—that revolved around an extremely massive black hole.
The galactic disk came to contain approximately four hundred billion stars, many of them developing over the succeeding eons planets that orbited them. By the time of the reign of the Galactic Empire, which began in 19 BBY, much was known about the physical properties of the galaxy, but only around a quarter of all the galaxy's stars had been surveyed by that point. Based on mathematical statistics of the explored galaxy, it was estimated that approximately 3.2 billion star systems could support life and that one billion of those systems were inhabited by sentient beings. Despite approximately one quarter of the galaxy having been surveyed by that time, more than five million sentient species were known to the Empire, implying many more were yet to be encountered.
Since 13,000,000,000 BBY, multiple galaxy-spanning civilizations and political entities rose and fell, including the Celestials, the Infinite Empire, the Galactic Republic, the Galactic Empire, the New Republic, the Yuuzhan Vong empire, the Galactic Alliance, and Darth Krayt's Galactic Empire. The reign of those factions was marked by a series of galactic-scale conflicts.
Although the 2001 reference book The Essential Guide to Alien Species by Ann Margaret Lewis originally established 5,000,000,000 BBY as the approximate date for the creation of the galaxy, that date was eventually overridden by the 2009 book The Essential Atlas, authored by Daniel Wallace and Jason Fry, which instead placed the galaxy's origin in 13,000,000,000 BBY.
- The Essential Atlas