“…The slow spin of the bilobate, cold classical Kuiper belt object (CCKBO) Arrokoth (formerly 2014 MU 69 )—revealed by NASA's New Horizons in 2019—as well as its gravitational surface slope distribution and structural integrity, suggest that Arrokoth is a remarkably low‐density body, ∼250–500 kg m −3 (see Hirabayashi et al., 2020; Keane et al., 2022; Mao et al., 2021; McKinnon et al., 2020; Spencer et al., 2020; Stern et al., 2019; and below). Such a density is at the lower end of estimates for cometary nuclei (with which Arrokoth likely shares a similar formation history; Nesvorný, 2018; Morbidelli & Nesvorný, 2020), and is even lower than that of 67P/Churyumov‐Gerasimenko (67P), 532 ± 7 kg m −3 (Groussin et al., 2019).…”