Fun Concept!
While there are a couple things that would help the player like mass numbers displayed, mini map, or zoom option, this game is pretty fun as it is. Its sort of like Orbient for the Wii.
Survival mode is beatable (but sadly, you cannot submit your score when you do since you have to die to do so). Over time, large stars spawn in the middle and asteroids can appear anywhere. It may take some time to slowly (safely) pick up asteroids. The gravity well that develops is like this on the map (numbers represent gravity power):
000010000
001121100
01+222+10
012333210
122333221
012333210
01+222+10
001121100
000010000
0 = safe in corner (you can leave the game safely), most edges minimal if any pull
1 = slight gravity, but if you're not paying attention you could fall in quickly
2 = you will probably die except in the beginning when there are few stars
3 = star spawn area, you're dead
+ = end of safe zone, best place to go in for more asteroids
What you want to do is make passes around the edge of the map or perhaps a screen out from the edge, being ready to fight any gravity you encounter and pick up a few asteroids. When you cannot find any more, head slowly from a corner diagonally to where the edge of the pull begins (the "+" areas on this graph). Float a bit to each side, allowing you to pick up some more asteroids, but don't move too deeply inside the gravity well. Repeat this for each side of the map; it will take time, but it is safe once you practice it. As you get to be a mid-sized to large sun, you will be pulled less and more things will come to you easily. Eventually you will reach a critical mass and pull stars out when not in a corner of the map, and you will be unable to die.