Nobody truly knows !... Our understanding of life and our planet - is limited by the knowledge we have of our immediate surroundings. There is presently no way of knowing if or whether there are other inhabited planets out there in the rest of the Universe - and whether that life is 'intelligent'.
Earth is the only planet which is known to harbour life.
Earth is the only planet with known life... so far.
LIFE.
Earth is the only planet known to support and have intellegent life.
Earth is called a life sustaining planet because it has life on it, and is currently the only known planet that supports life.
Earth is the only planet known to have life and liquid water.
Earth is the only planet which is known to harbour life.
planet earth is known for being the only planet to support life
Earth
Earth is the only planet with known life... so far.
Earth is the only planet currently known to have life.
Earth
LIFE.
Earth is the only planet known to support and have intellegent life.
Earth is the only planet known to support life.
Because Earth is the only planet known to have life.
earth