It may surprise you, but oxygen has only been a part of Earth's atmosphere for an estimated 10 percent of the planet's history. Yes, we're still talking millions of years, but the fact that it's a relatively new addition to the air we breathe can have implications when we study potential Earths outside our solar system.

School of Earth and Atmospheric Sciences Assistant Professor Chris Reinhard researches the early Earth, along with recently discovered exoplanets, as part of his team's studies in his Earth Systems Science Lab. What he’s searching for are atmospheric biosignatures – molecules detectable in an atmosphere that may indicate life on the surface.

Episode 2 of ScienceMatters details that search, and how close Reinhard thinks we are to discovering Earth 2.0. Reinhard is currently working on a NASA-funded project to determine the kind of atmosphere Earth had four billion years ago. The results could help determine the types of instrumentation uncrewed probes will have when they are launched toward potentially habitable moons and planets.

Each episode will also include a quiz that refers to facts mentioned in each podcast. A winner will be chosen randomly from all who submit correct answers. Winners will receive special College of Sciences merchandise such as t-shirts and pens.

The episode 2 quiz question:

Chris Reinhard believes that only one exoplanet found so far outside our solar system comes closest to resembling Earth. What is the name of this exoplanet?

The winner will be announced in the following week.

Submit your answer here: https://forms.cos.gatech.edu/sciencematters-season-3-episode-2.

ScienceMatters podcasts are available for subscription at Apple Podcasts and Soundcloud.