Does planet nine exist? Where is planet x?Motivated by recent measurements of the free-floating planets, a new paper considers the possibility that the solar system may have captured a terrestrial planet early in its history.

Amir Siraj is a theoretical astrophysicist (Harvard University A.M. ’22, A.B. ’22) and concert pianist (New England Conservatory of Music, M.M. ’23). He is currently pursuing his Ph.D. at Princeton University’s Department of Astrophysical Sciences. CNN called his work one of ten “extraordinary cosmic revelations” in 2022, and he was the youngest scientist named to the Forbes 30 Under 30 list in 2021. Recently named one of Astronomy Magazine’s 25 Rising Stars, Siraj seeks to understand the solar system in the context of its cosmic environment through research topics including: interstellar objects, asteroids and comets, planetary system formation and evolution, supernovae, black holes, dark matter, and the search for life in the universe.

Are There Terrestrial Planets Lurking in the Outer Solar System?https://arxiv.org/abs/2312.08431