NASA 宇宙の記録
今日の天体写真 (APOD)= カレンダーから選ぶ「宇宙の神秘」=

What do stars look like just before they explode? To find out, astronomers are taking detailed images of nearby galaxies now, before any supernova is visible. Hopefully, a star in one of the hundreds of high resolution galaxy images will explode in the coming years. If so, archival images like that taken above by the Hubble Space Telescope can be inspected to find what the star looked like originally. This information is likely important for better understanding of how and why supernovas occur, as well as why some supernovas appear brighter than others. Pictured above, beautiful spiral galaxy NGC 3982 displays numerous spiral arms filled with bright stars, blue star clusters, and dark dust lanes. NGC 3982, which spans about 30,000 light years, lies about 60 million light years from Earth and can be seen with a small telescope toward the constellation of Ursa Major.