Seeing The Sun

In 2006 NASA launched a complex space mission to give humans our first complete perspective view of the Sun. Prior to this mission we could only observe one side of the Sun at a time. The mission has achieved its initial goal, and now it is also yielding important information about how the sun affects the Earth. 

The mission began when a spacecraft called STEREO-A (for “Ahead”) was sent into orbit around the Sun, and was then followed by the launch of its partner STEREO-B (for “Behind”). Using these two vehicles together would enable a three-dimensional view of the Sun. In 2011, the dual spacecraft mission achieved its goal by providing the first stereoscopic view of our closest star. “A” and “B” had finally reached a 180-degree separation in their orbits, and for the first time, humanity saw our Sun as a complete sphere. 

In 2023 STEREO-A came close to the Earth for the first time since its launching 17 years before, and scientists are using that opportunity to study solar flares. These ejections of solar mass are often harmless, but sometimes they can disrupt satellite and radio signals, or even cause surges in our power grids. There is also evidence that these powerful flares are an important cause of climate change on Earth. During the time that STEREO-A is near the Earth, any solar flares that pass over it will give scientists much needed measurements from inside the flare. This will allow them to build models that can predict the behaviour and consequences of future solar flares.