Oxygen on Exoplanets May Not Mean Alien Life

Although scientists have long considered oxygen a sign that life exists on an alien planet, new research suggests the element could be produced without it. Oxygen may function as a sign of life on Earth, but that's not necessarily the case for planets around other stars. The new research shows that the interaction of titanium oxide with water could produce oxygen in the atmosphere of an exoplanet without the involvement of living organisms.