Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
After 30 years of planning and negotiations, construction begins this week on the Square Kilometre Array (SKA), the world’s largest radio-astronomy observatory. The giant instrument — to be built across sprawling sites in Australia and Africa — will collect the radio signals emitted by celestial objects and will hopefully shed light on some of the most enigmatic problems in astronomy, such as the nature of dark matter and how galaxies form.