In the year 20 BA Humans finally succeeded in achieving interstellar travel, made possible by entering and exiting another dimension in which faster-than-light speeds are possible. The Humans quickly discovered that a Breach already existed in the Solar System, and upon following it to its destination, they found themselves in a distant galaxy, which they named Nova Refuge. Near the exit Breach was the first naturally-habitable planet ever discovered other than Earth, which they named Terra Nova. They quickly begin exploration and colonization of this "New Earth," founding four main scientific colonies, including Victory Station and XARCON and XARCOS (eXtraterrestrial Advanced Research and Colonization Outpost North/South). These outposts soon grew into colonies as entrepreneurs and brave pioneer settlers followed.
At some point scientists noted increased activity on the surface of the Sun, in the form of extremely powerful solar flares happening in great frequency. One English scientist named Arthur Randolph wrote a book titled The Death of the Sun, in which he claimed that the Sun was dying at a rapid rate and that it would soon explode in a supernova that would engulf the entire Solar System. Randolph called for an evacuation of everyone on Earth to Terra Nova. When Earth's governments refused to call for an evacuation, Randolph left for Terra Nova with his entire family, becoming head scientist of the XARCON base.
In the year 4 BA a team of young scientists, lead by Dr. John Gaston, was put together by Earth's largest mega-corporation TerraCom, to monitor the Sun and prove Dr. Arthur Randolph's theories wrong, but instead they confirmed them to be correct. Following the discovery the Great Exodus begun, and official evacuation ships, built long in advance, begun taking thousands of refugees to Terra Nova, populating the scientific colonies on the new planet.
In the year 0 PA the last of the evacuation ships left Earth as the Sun went supernova, destroying the entire Solar System in the process.