• We stated that Alexandra Horowitz from Barnard College in New York believes that dogs have a “theory of behaviour” rather than a “theory of mind” (23 August, p 33). She was merely pointing out an alternative explanation for some experiments in dog cognition: her own view is that dogs do have a rudimentary theory of mind.
• Marcus Chown wrote: “The two stars of the Gamma Cephei system are 28 to 30 astronomical units (AU) apart, roughly equal to the distance between the sun and Uranus” (23 August, p 40). The semimajor axis of Uranus is 19 AU; the distance between the sun and Neptune is 30 AU.
