NASA's next great observatory could spot oceans on distant worlds

NASA's next great observatory, the Habitable Worlds Observatory (HWO), could potentially detect oceans on distant exoplanets by observing "glint," a specular reflection phenomenon. The study, by Eleanor Cornish and Tyler Robinson of the University of Arizona, uses a modified atmospheric tool called rfast to detect this glint. The tool incorporates the Cox–Munk ocean model to simulate how wind and wave patterns affect light reflected back to telescopes. The researchers found that even at relatively high noise thresholds, the model could differentiate between planets with and without oceans, provided they were viewed at a phase angle of more than 120°. This is significant because at higher angles, starlight scatters more, leaving red light, which is a key indicator of ocean glint. The study highlights that the model can differentiate between planets with and without oceans, even with some cloud cover, but acknowledges the challenges posed by clouds and the need for more data about Earth's crescent phase.

The researchers found that the model can detect ocean glint even when there is some cloud cover, but the simulations assumed 50% cloud cover for an Earth-like world. In reality, many exoplanets are much more cloud-covered, which complicates the detection process. The study also notes that the model can differentiate between gas and liquid absorption bands, but it shows the challenges of detecting oceans on distant worlds. The findings are important for HWO, as they provide a tool to detect ocean glint, which is crucial for the observatory's mission. The study also emphasizes that the tool can be used with some as training data, which is crucial for HWO scientists to interpret the data they collect. The study concludes that with the right observation angle, it is possible to detect oceans on distant worlds, but the challenges of cloud cover and lack of data about Earth's crescent phase remain.

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