Asteroid
The asteroid is an event that starts when a new avatar enters the universe. Their starting world will be in danger and need saving.
The asteroid is explained by the stargazer of a village.
Time Until Impact
The time before the asteroid will impact is a week or 168 hours from when the avatar first spawns on the world.
Detection
Cities with an observatory report the presence of an asteroid in its solar system, which is necessary to detect asteroids at extreme range. Asteroids known to be on a collision course with a world will cause an event log alert in the city report.
Space stations with sensors or cities with radar will also report asteroids in the their event log, if they are detected within sensor range.
The asteroid is always marked as enemy, and can thus be targeted from a fire control station by both AI and avatars. It will also appear on the Unit list for attack and follow orders.
Impact
Depending upon the size difference between the asteroid and the world world being impacted, devastation could range from destruction of all cities on the world, to complete annihilation of the world body.
Asteroids of any size is are absorbed by gas giants harmlessly.
Extinction Level Event
When a smaller asteroid impacts a world it will create a huge crater, and all cities and buildings on the world are destroyed.
World Annihilation
If a planet is destroyed, it will turn into an asteroid belt with possibly a tiny belt asteroid world.
The moons of a world are unharmed, unless subsequently hit by another asteroid. They will spin on an additional axis and tumble in the asteroid belt.
If a moon or titan is destroyed by an asteroid impact, it will become a planetary ring. A planetary ring that is left behind when its planet is destroyed will disappear.
Destruction
The goal is to develop the needed technology to get into space and blowup the asteroid.
You will only be able to see and attack the asteroid once it physically spawns in the system, which is 8 hours before the impact time.
The asteroid can be destroyed by a space fighter, a spacecraft with weapons, or military weapon systems.
The asteroid will slowly break down into smaller pieces as it is damaged.
Note: It is not recommended to use military weapon systems to attempt to destroy asteroids, as they will not be able to damage the asteroid enough by the time it gets into range.[1]
References
Haxus visited the homeworld of Tamunshin to help with an asteroid, however they were unable to destroy it before the impact. Haxus recorded a video of the impact which can be seen here: http://hazeron.com/Playlists/Scenes%20of%20Hazeron/AsteroidImpact.mp4
Also, this was discussed in this thread on the forums: http://hazeron.com/mybb/showthread.php?tid=2062