Laura Kreidberg: Trying to Spot the First Sign of Life Outside Earth

Laura Kriedberg, a junior fellow with the Harvard Society of Fellows and an astronomer at the Harvard-Smithsonian Center for Astrophysics, is on a mission to find out life outside Earth. More precisely, he his looking for biosignatures, tell tale atmospheric signs of possible life on faraway extra-solar planets, or exoplanets. 
She said a planet's atmosphere is the key to understanding how it was formed and how it evolved over billions of years. 
Astronomers are yet to find evidence of extra-terrestrial life, but the huge presence of extrasolar planets offers hope that there is some out there.he study of extrasolar planets is still a relatively new field. Their existence was only visually confirmed 24 years ago (though astronomers have hypothesized their existence since the 16th century). Today, more than 3,000 exoplanets have been discovered and close to 5,000 other bodies have been identified as candidates for life. They range from gas giants to ice worlds to Earth-like exoplanets that sit in their solar system’s habitable zone. 
To study their atmospheres, Kreidberg uses a method called transmission spectroscopy. During observations, she measures the color of light that passes through a planet’s atmosphere when it passes in front of the star it orbits. That measured light is called the planet’s transmission spectrum. The color of light that gets absorbed by the atoms and molecules in the planet’s atmosphere tells her about its composition.