NASAさんのインスタグラム写真 - (NASAInstagram)「These cosmic sparklers light up the night sky. 🎇✨ Happy Fourth of July, from all of us at NASA Goddard! . This is actually a map of the sky in X-rays, recorded by NICER: a payload on the International Space Station. Many celestial objects emit X-rays, such as stars and active galaxies. X-ray astronomy helps us understand how these objects emit such powerful light. . The map includes data from the first 22 months of NICER’s science operations. Each arc traces X-rays, as well as occasional strikes from energetic particles, captured during NICER’s night moves. During the orbital night, NICER stays on even while it swings from target to target. The brightness of each point in the image is a result of these contributions as well as the time NICER has spent looking in that direction. A diffuse glow permeates the X-ray sky even far from bright sources. The prominent arcs form because NICER often follows the same paths between targets. The arcs converge on bright spots representing NICER’s most popular destinations — the locations of important X-ray sources the mission regularly monitors. Credits: NASA/NICER」7月5日 0時23分