• The Dark Energy Survey will catalogue 2000 supernovae that exploded in the last 7 billion years (11 April, p 6).
• Sunlight provides the Earth with 120,000 terajoules per second of power, not terawatts as we stated (4 April, p 24).
• In a story on Alzheimer’s, we misspelled the name of Stanford University neurologist Michael Greicius (11 April, p 10).
