title: Mercury has two permanent thermal bulges.
abstract: If Mercury has been rotating with, a period exactly two-thirds of the period of orbital revolution for at least 60,000 years, there exist two permanent thermal bulges on opposite sides of Mercury's surface that alternately face Sun at every perihelion. The bulges increase the strength of the resonance lock and tend to prevent drifting out.
authors.forename: H S
authors.initials: HS
authors.lastname: Liu