Researchers are exploring the idea that earth may be uniquely situated in a "chemical goldilocks zone" that supports life. A new study suggests that this zone may be rare, but the discovery of a nearby earth-size planet and a super-earth exoplanet has raised questions about whether earth is indeed the only planet capable of supporting life. The existence of other potentially habitable planets, such as "toi 700 d", is also being considered as a possible "goldilocks planet".