Within Influence, Asteroids serve as your land in-game. They will allow you to build infrastructure and participate in the ever-changing and growing universe within Influence. Adalia is made up of 250,000 asteroids, each with a unique composition of materials, and varying attributes that allow it to produce a unique play experience for the owner of the land.
You can learn more about asteroids HERE
There are many different factors that go into this, however some great information can be found HERE. Within the testnet this isn’t very important, so until you are more knowledgable about the game don’t worry about it.
Using the filters tab within the map you can search for different parameters. The biggest tip is that when “purchasing” asteroids the price is determined by the size, the larger the asteroid the more it costs. In testnet this is free, but you will still need the correct amount of test credits (GoETH). So the best thing to do is filter for asteroids in the smallest category.