This is an artist impression of exoplanet LTT9779b orbiting its host star. The planet is around the size of Neptune and reflects 80% of the light shone on it, making it the largest known “mirror” in the Universe. This shininess was discovered by detailed measurements made by ESA’s Cheops of the amount of light coming from the planet-star system. Because the planet reflects starlight back to us, the amount of light reaching Cheops’ instruments slightly decreased when the planet moved out of view behind its star. This small decrease could be measured thanks to the high precision of the detectors.

Read more.