Aurora is on version 7.1, available at the Aurora Forums.
Contact Erik on the forum for a wiki account.
The solar Disaster scenarios, are optional rules, which can be toggled from the Game Details screen. Disaster are mainly used for RP purpose, an exodus scenario in which the player need to get out of his home-system before the inevitable end.
If disaster scenario is in play, such as the Sun gradually heating, then planetary environments in the affected system are updated. So eventually your planet will be outside of the habitable zone. It takes around ??? years for a warming sun to reach a point at which it starts affecting habitability Earth, and Mars will last longer. You can invest resources to hold it off for a fair while, using anti-greenhouse gas, but it will eventually overwhelm that. Better start looking for other colonize-able worlds nearby and building a hell of an ark.
Note, Disasters are for a purely player driven game, the NPRs do not take this setting into account.