Apparently only a few can realize of their dream of exploring the universe, but if you want, the following simulation game Tiny Solar may be a nice idea.
Tiny Solar is an outer space themed, sand-box simulation game developed by 6Nice Studio, and designed for iPhone and iPod touch. The iPhone game provides a randomly generated universe, while you, as a tiny dust need to navigate in the vast infinite universe and grow from a single fragment to a planet, living planet, little star, middle star, huge star, galaxy and finally to a black hole which can swallow everything. Of course, before this you must avoid various dangerous planets that is more powerful than yourself and aggressive fleets. Moreover, the sand-box also has a mission mode that contains more than 30 various tasks. Apart from that, the simulation game supports Game Center with achievements and leaderboards.
Tiny Solar with a size of 14.0 MB is compatible with iPhone (optimized for iPhone 5), iPod touch and iPad running iOS 4.3 or later. The iPhone game is free for a limited time at present. If you’re interested, jump to App Store for more details.