  The recent discovery of seven potentially habitable Earth-size planets around
the ultra-cool star TRAPPIST-1 has further fueled the hunt for extraterrestrial
life. Current methods focus on closely monitoring the host star to look for
biomarkers in the transmission signature of exoplanet's atmosphere. However,
the outcome of these methods remain uncertain and difficult to disentangle with
abiotic alternatives. Recent exoplanet direct imaging observations by THIRSTY,
an ultra-high contrast coronagraph located in La Trappe (France), lead us to
propose a universal and unambiguous habitability criterion which we directly
demonstrate for the TRAPPIST-1 system. Within this new framework, we find that
TRAPPIST-1g possesses the first unambiguously habitable environment in our
galaxy, with a liquid water percentage that could be as large as $\sim~90~\%$.
Our calculations hinge on a new set of biomarkers, CO$_2$ and
C$_{x}$H$_{2(x+1)}$O (liquid and gaseous), that could cover up to $\sim~10~\%$
of the planetary surface and atmosphere. THIRSTY and TRAPPIST recent
observations accompanied by our new, unbiased habitability criterion may quench
our thirst for the search for extraterrestrial life. However, the search for
intelligence must continue within and beyond our Solar System.
