Revealing the fascinating mystery of the sky at witching hour, this image presents 22 months of X-ray data collected by NASA's Neutron Star Interior Composition Explorer (NICER) mission aboard the International Space Station during its nightly rotations.

NICER's main goal is for the space station to target and monitor different cosmic sources every 93 minutes as it orbits the Earth. However, when the Sun sets and night comes, the NICER team keeps its detectors active, continuing to collect data during the instrument's passage from target to target, which can occur up to eight times in each orbit.

Each curve traces the X-rays captured during these nightly rotations, as well as the occasional impact of energetic particles. The intensity of each bright spot in the image is the result of the duration of NICER's observations of that region. Even far away from bright sources, X-rays create a glow that spreads across the sky.

Image description: Shows a network of a series of bright dots connected by orange filaments on a black background. These dots mark the intersection of sources in the sky that NICER frequently targets and tracks. The loops show the path of NICER's telescope between these sources.

The image is watermarked "NASA/NICER".