Solar Stormwatch was the first space weather citizen science project, the aim of which is to identify and track coronal mass ejections (CMEs) observed by the Heliospheric Imagers aboard the STEREO satellites. The project has now been running for approximately 4 years, with input from >16,000 citizen scientists, resulting in a data set of >38,000time‐elongation profiles of CME trajectories, observed over 18 preselected position angles. We present our method for reducing this data set into a CME catalogue. The resulting catalogue consists of 144 CMEs over the period January 2007 to February 2010, of which 110 were observed by STEREO‐A and 77 were observed by STEREO‐B. For each CME, the time‐elongation profiles generated by the citizen scientists are averaged into a consensus profile along each position angle that the event was tracked. We consider this catalogue to be unique, being at present the only citizen science‐generated CME catalogue, tracking CMEs over an elongation range of 4° out to a maximum of approximately 70°. Using single spacecraft fitting techniques, we estimate the speed, direction, solar source region, and latitudinal width of each CME. This shows that at present, the Solar Stormwatch catalogue (which covers only solar minimum years) contains almost exclusively slow CMEs, with a mean speed of approximately 350 km s−1. The full catalogue is available for public access at http://www.met.reading.ac.uk/~spate/solarstormwatch. This includes, for each event, the unprocessed time‐elongation profiles generated by Solar Stormwatch, the consensus time‐elongation profiles, and a set of summary plots, as well as the estimated CME properties.

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‘Thunder days’ are simple records of thunderstorm activity, logging whether a human observer heard thunder on a particular day or not. Despite their low dynamic range and inherent subjectivity, thunder days are invaluable as the only long‐term observations of thunderstorm occurrence, with some records stretching back into the nineteenth century. Thunder days, however, are potentially susceptible to false positives, particularly from explosions. Thus one might expect UK thunder days to show anomalously high counts on New Year's Eve and the days around 5 November, Bonfire Night, both of which are celebrated with large firework displays across the country. It is demonstrated that UK Met Office records of thunder days between 1980 and 2010 do not show any significant increase in thunder reporting around 5 November or 31 December. In fact, the days around 5 November exhibit the largest reduction in the amount of reported thunder relative to annual climatology. While meteorological variability cannot be completely ruled out, this result is suggestive of observer bias; it is speculated that human observers, armed with a priori knowledge of the likelihood of false positives, ‘second guess’ themselves to a greater degree around 5 November than the rest of the year. In fact, the data suggest they should trust in their ability to correctly discriminate between thunder and fireworks.

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Mike Lockwood and Mat Owens discuss how eclipse observations are aiding the development of a climatology of near-Earth space