What we thought were 'exact' weights for planets in other solar systems might actually just be a trick of the math we were using.
April 13, 2026
Original Paper
The Illusory Precision of TTV Masses: Hidden Solutions Behind Kepler-9's Tight Mass Ratio
arXiv · 2604.09268
The Takeaway
Astronomers realized that their standard tools for weighing planets had a major blind spot. This means many of the masses we've calculated for alien worlds might be just one of many possible, and potentially wrong, answers.
From the abstract
Transit timing variations (TTV) are considered a tool for constraining the masses of transiting planets in the absence of radial-velocity data. Although theoretical studies have long revealed that TTV mass determinations intrinsically suffer from degeneracies, existing analyses of TTV data typically report a single-mode solution under a model with a specified number of planets. This is because fitting TTV curves in the high-dimensional solution space of TTV posterior is extremely challenging; ev