Complex sentence: The discovery of exoplanets has intensified interest in the search for extraterrestrial life, particularly for those that orbit in the host star's habitable zone where it is possible for liquid water (and therefore life) to exist on the surface.
Split into simpler sentences: The discovery of exoplanets has intensified interest in the search for extraterrestrial life. There is special interest in planets which orbit in a star's habitable zone, where it is possible for liquid water (and therefore life) to exist on the surface.