Red giant star Pi1 Gruis, VLTI image. This image of a red giant star was obtained using the PIONIER instrument on ESO's Very Large Telescope Interferometer (VLTI). PIONIER is the precision integrated-optics near-infrared imaging experiment. The image shows directly observed granulation patterns on the surface of the star. Each convective cell measures about 120 million kilometres across. Pi1 Gruis is around 530 light years from Earth, in the constellation of Grus. Image published in December 2017.