The emerging field of extrasolar planet search has shown an extraordinary ability to combine research by astrophysics, chemistry, biology
and geophysics into a new and exciting interdisciplinary approach to understand our place in the universe. Are there other worlds like ours?
How can we characterize those planets and assess if they are habitable? After a decade rich in giant exoplanet detections, observation
techniques have now reached the ability to find planets
of less than
(so called Super-Earths) that may potentially be
The detection and characterization of Earth-like planet is approaching rapidly with dedicated space observatories already in
operation (Corot) or in development phase (Kepler, James Webb Space Telescope, Extremely Large Telescope (ELT), Darwin/TPF). Space missions
like CoRoT (CNES, Rouan et al. 1998) and Kepler (NASA, Borucki et al.
give us statistics on the number, size, period and orbital distance of planets, extending to terrestrial planets on the
lower mass range end as a first step, while missions like Darwin/TPF are designed to characterize their atmospheres.
In this chapter we
how we can read a planet's spectral fingerprint and characterize if it is potentially habitable.
We discuss the first steps to detect a habitable planet and set biomarker detection in context in Section 1. In Section 2 we focus on
biomarkers, their signatures at different wavelengths, abiotic sources and cryptic photosynthesis – using Earth as our primary example –
the only habitable planet we know of so far. Section 3 concentrates on planets around different stars, and Section 4 summarizes the chapter.