Comment Re:Title: NASA Has Discovered an Earth-Sized World (Score 1) 59
The system can very well have multiple planets, but have only a single planet within the habitable zone. The zone does not exist as the entire radial distance from the host sun, but as a ring. For example, Mercury would not be in our habitable zone. It is far too hot to sustain life. A solar system could theoretically have 5 planets around a sun as relatively close and hot as Mercury, and then a single planet much farther away within the habitable zone. This description also leaves open the possibility of other planets further out that haven't been discovered yet either inside or outside the habitable ring.
Yeah, that part is junk.