Since the first exoplanet discovery in the 1990s, scientists have learned of the diverse and abundant nature of exoplanets, having now found more than 3700. With such a large and disparate sample set, ESA (European Space Agency) has set its sights on learning how these planets form and what their chemistry is like. A new telescope, or ‘mission’, ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey), has been approved and will investigate the atmospheric composition of exoplanets.
Direct observation of exoplanets is difficult due to the bright, nearby stars they orbit. Astronomers often compare it to staring into a far-off stadium light (the star) and looking for a nearby firefly (the planet). To begin studying the exoplanets’ composition, scientists will use the star’s light filtering through the exoplanet’s atmosphere to identify the chemical composition – effectively looking at the color of the firefly’s wings as it passes in front of the stadium light. This is known as spectroscopy.
ARIEL is the first mission dedicated to this study and will be a space-based telescope. It can provide a wider viewing range of space while simultaneously distancing itself from Earth, where our own planetary atmosphere can interfere with ground-based observations. Giovanna Tinetti, principal investigator for this mission, says that ARIEL will help build a ‘standard model’ of how a planet’s chemistry depends on its star and the condition of its birth, helping to better establish the habitability of a planet. For the first time, scientists (ranging from planetary scientists to astrobiologists) will be able to relate planetary composition, characteristics, and formation to its solar neighbors and host star – and perhaps, in turn, help us better understand Earth’s place in the Universe too.