How to randomize planets in the SF Universe

<br />I'm at a loss on how to start with this because I don't know &quot;how big&quot; the SF Universe is.<br /><br /><br /><ul><li>How often will a new planet be discovered? (It's not Star Wars....)</li><li>How often will GM's use this tool?</li><li>What systems have not been fully researched?</li><li>How Big is the Frontier? Is there a 3-D map?</li></ul>anyone see where I'm going?<br /><br /><br />