A third object from another star system just flew into our neighborhood, and it’s basically propelling itself like a natural rocket.
arXiv · March 18, 2026 · 2603.15735
The Takeaway
Following 'Oumuamua and Borisov, this new visitor from another star system is shedding gas so rapidly that the 'rocket effect' is physically pushing it off its gravitational course. Scientists used this acceleration to calculate that it is a dense, icy nucleus much smaller than previously estimated.
From the abstract
Observations of the interstellar object 3I/ATLAS have revealed a strong production of gas and dust near perihelion, together with rapid brightening. The outgassing from the nucleus has led to a detectable non-gravitational acceleration. In this work, we combine models of the mass loss rate of water and carbon dioxide to derive the non-gravitational parameters and estimate the mass and size of 3I/ATLAS. In addition, we take into account a conservative constraint on the nucleus size from the activ