Were getting closer and closer to finding a real Earth-like exoplanet. But finding one is only half the battle. To truly know if were looking at an Earth analog somewhere else in the galaxy, we have to directly image it too. Thats 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 isnt enough, according to a new paper available in pre-print on arXiv by Kaz Gary of Ohio State and their co-authors. HWO will need to figure out how much a planet weighs first.