Earth as a Proxy Exoplanet: Deconstructing and Reconstructing Spectrophotometric Light Curves

Point source spectrophotometric ("single-point") light curves of Earth-like planets contain a surprising amount information about the spatial features those worlds. Spatially resolving these is important for assessing time-varying surface and existence an atmosphere, which in turn critical to life on Earth significant determining habitability exoplanets. Given that only celestial body confirmed harbor life, treating it as proxy exoplanet by analyzing time-resolved spectral images provides benchmark search habitable The Polychromatic Imaging Camera (EPIC) Deep Space Climate Observatory (DSCOVR) such opportunity, with observations ~5000 full-disk sunlit each year at ten wavelengths high temporal frequency. We disk-integrate create single-point decompose them into principal components (PCs). Using machine learning techniques relate PCs six preselected features, we find first fourth curves, contributing ~83.23% curve variability, low clouds, respectively. Surface relevant contrast between land ocean reflectance contained second PC, while individual sub-types are not easily distinguishable (<0.1% total variation). build model systematically altering derive causal relationships PCs. This can serve baseline exoplanets guide wavelength selection sampling strategies future observations.