NASA's Imaging X-ray Polarimetry Explorer, or IXPE, is a space observatory built to discover the secrets of some of the most extreme objects in the universe - the remnants of supernova explosions, powerful particle streams spit out by feeding black holes, and more. IXPE is NASA's first mission to study the polarization of X-rays from many different types of celestial objects. Measuring the polarization of X-rays traces the story of where this light came from, including the geometry and inner workings of its source. IXPE launched Dec. 9 on a Falcon 9 rocket from NASA's Kennedy Space Center in Florida to its orbit about 370 miles (600 kilometers) above Earth's equator.