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Recording of the webinar on Nov 24, 2020 in the SPIE Poincaré series on polarimetry and polarization-based optics and phenomena. This talk to a relatively broad audience presents the work by our group in Leiden on polarization techniques for direct observations and characterization of exoplanets, and spin-off applications here on Earth.

Abstract:
The vast majority of information about our universe comes to us in the form of light. The polarization of the light from astronomical objects can uniquely elucidate e.g. their substructures and magnetic fields. But polarization-based techniques and polarimetry are also crucial to answer one of humanity’s biggest questions: “Are we alone?”. We now know from indirect methods that every star in the sky hosts at least one planet, but is still extremely challenging to actually see these planets. For instance, an Earth analog orbiting a solar-type star is ten billion times fainter in visible (reflected) light. That light is, however, polarized, which enables us to boost the contrast by orders of magnitude, and unambiguously characterize the planetary atmosphere and surface. We combine polarimetry at systems level with adaptive optics, wavefront sensing, and coronagraphy, all of which employ polarization-based and liquid-crystal techniques, and enable broadband operation and spectroscopy/spectropolarimetry. To prepare for direct observations of Earth-like exoplanets with future extremely large ground-based telescopes and dedicated space telescopes, we use the Earth for target practice. We are developing dedicated spectropolarimeters to observe the Earth-as-an-exoplanet from the ISS and from the Moon, and perform circular polarimetric observations of vegetation and beetles to establish remote-sensing of homochirality as a powerful biomarker. All this work also leads to spin-offs in Earth observation, e.g. to measure the effects of air pollution on our climate and our health from the next NASA climate satellite PACE, and by thousands of citizen scientists.

The answer to the Ultimate Question of Life, the Universe and Everything is... polarized!