Not much is known about what lies outside the Colonies. No stellar bodies have been surveyed during the flight of the Sleeper Ships; the two sleeper ships launched before the war did not return much useful information either - in fact, one of them, the Mayflower, did not return at all, while the other one arrived in Sirius at the dawn of the 9th Century only to bring news of the demise of their own home by a natural disaster.
This is what I found on Discovery Wiki...
Let's discuss, what could happened to that "Mayflower"... Who will be the first one? Any minds?