It's an issue that will affect how we spend billions of dollars, and how future decades of exploration will unfold. We're not just talking about poor little Pluto. We're talking about a convergence of developments that will widen our view of the solar system and what lies beyond:

Just last month, President Barack Obama announced that the first destination beyond Earth orbit for human space flight would not be the moon, but an asteroid--one of the solar system's "minor planets." If that goal holds true, billions of dollars will be spent over the next 15 years to send astronauts to what's officially considered a non-planet.

During the past 15 years, more than 450 planets have been detected beyond our solar system, and hundreds more are expected to be found, thanks to NASA's recently launched Kepler mission. Some of those planets will be Earth-like worlds orbiting sun-like stars, in circumstances that could support life as we know it. And some of the planets already discovered do not fit the definition of planethood as currently described.

Over the next decade, more than a billion dollars will be spent on telescopes with acronym-heavy names such as Pan-STARRS and LSST--telescopes that could spot tens of thousands of previously unseen ice dwarfs on the rim of our solar system. In the first week after the LSST begins operation, "we will see more data from this telescope than all the telescopes in humanity up to that point," said software billionaire Charles Simonyi, one of the project's backers.