Readers react to a dwarf planet’s odd ring, dry farming and more
Sizing up rings
The dwarf planet Quaoar sports a ring that lies outside the orb’s Roche limit, an invisible line beyond which rings aren’t thought to be stable, Lisa Grossman reported in “This dwarf planet hosts an odd ring” (SN: 3/11/23, p. 11).
Reader Henry Leonard wondered if it’s possible the ring isn’t so unusual, that perhaps Quaoar simply has an unexpectedly large mass, resulting in a large Roche limit.
Astronomer Bruno Morgado of the Federal University of Rio de Janeiro is certain that the dwarf planet’s ring is an oddball. Morgado’s team used the orbital motion of Quaoar’s satellite, Weywot, to determine the dwarf planet’s mass.