You're browsing the GameFAQs Message Boards as a guest. Sign Up for free (or Log In if you already have an account) to be able to post messages, change how messages are displayed, and view media in posts.
However, I do believe it may be possible to complete the levels on Earth before you get the last Earth map and Earth appears. But that would take incredible luck and a lot of time, because Earth's position is random.
This wall of text has been brought to you courtesy of one of the board's resident spectrum children (and Linux users).