This image from NASA's Kepler spacecraft shows members of the Pleaides star cluster taken during Campaign 4 of the K2 Mission. The cluster stretches across two of the 42 charge-coupled devices (CCDs) that make up Kepler's 95 megapixel camera.
The brightest stars in the cluster - Alcyone, Atlas, Electra, Maia, Merope, Taygeta, and Pleione - are visible to the naked eye. Kepler was not designed to look at stars this bright; they cause the camera to saturate, leading to long spikes and other artefacts in the image. Despite this serious image degradation, a new technique has allowed astronomers to carefully measure changes in brightness of these bright stars as the Kepler telescope observed them for almost three months.