We're getting closer and closer to finding a real Earth-like exoplanet. But finding one is only half the battle. To truly know if we're looking at an Earth analog somewhere else in the galaxy, we have to directly image it too. That's a job for the Habitable Worlds Observatory (HWO), a planned space-based telescope whose primary job is to do precisely that. But even capturing a picture and a planet and getting spectral readings of its atmospheric chemistry still isn't enough, according to a new paper available on the arXiv preprint server by Kaz Gary of Ohio State and their co-authors. HWO will need to figure out how much a planet weighs first.
