All its parts have been built and put together. It has been wrapped in shiny gold insulating foil. Its launch is getting closer. But the Smile spacecraft had one major phase to pass before it could be certified ready for space – and it involved testing, testing and yet more testing.
Since Galileo first observed them through his telescope in the early 1600s, sunspots have fascinated scientists. These dark patches on the Sun's surface can persist for days or even months, but until now, researchers couldn't fully explain why they remained stable for such extended periods.

