• We misidentified a photo as showing the Microscopy, Electrochemistry and Conductivity Analyzer from the Phoenix Mars spacecraft (28 July, p 45). It actually shows part of the mass spectrometer for another instrument on Phoenix. Also, we said that Viking 2 landed on Mars on 3 September 1996: it was in 1976.
• We said that flames propagate so quickly through mixtures of gases that the changes in pressure create shock waves leading to an explosion (4 August, p 38). In fact, shock waves travel supersonically, much faster than the fireballs being described, and do not form part of John Dold’s hypothesis.
• Apologies to Alan Kostelecky, whose name we misspelled in the feature on neutrinos (4 August, p 30).
