2026年2月26日
Webb and Hubble: IC 5332
Image Credit: ESA/Webb, NASA, CSA, J. Lee and the PHANGS-JWST and PHANGS-HST Teams
Text: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)
Explanation: What does the universe look like through infrared goggles? Our eyes can only see visible light, but astronomers want to see more. Today’s APOD shows spiral galaxy IC 5332 as seen by two NASA telescopes: Webb in mid-infrared and Hubble in ultraviolet and visible light. To toggle between the two space-based views just slide your cursor over the image (or follow this link). The Hubble image highlights the spiral arms of the galaxy separated by dark regions, whereas the Webb image reveals a finer, more tangled structure. Interstellar dust scatters and absorbs light from the stars in the galaxy, causing the dark dust lanes in the Hubble image, and then emits heat in infrared light, so dust glows in this Webb image. The Mid-InfraRed Instrument on Webb needs to operate at a chilling temperature of -266ºC (or – 447ºF), otherwise it would detect infrared radiation from the telescope itself. Combining these observations, astronomers connect the “small scale” of gas and stars to the truly large scale of galactic structure and evolution.
Tomorrow’s picture: invertebrates in space
韦伯与哈勃: IC 5332
影像提供: ESA/Webb, NASA, CSA, J. Lee and the PHANGS-JWST and PHANGS-HST Teams
文稿: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)
说明: （IC 5332影像滑动对比与连结）透过红外线眼镜看宇宙会是什么样子？我们的眼睛只能看到可见光（因此得名），但天文学家想要看到更多。今天展示的图片是螺旋星系 IC 5332，分别由美国NASA的两台太空望远镜拍摄：詹姆斯·韦伯望远镜拍摄的中红外线波段影像和哈勃望远镜拍摄的紫外线和可见光影像。哈勃望远镜影像突显了星系中被暗区分隔开的巨大旋臂，而韦伯望远镜影像则展现了更细致且盘根错节的结构。星际尘埃会散射并吸收星系中恒星的光，在哈勃影像中形成了暗尘埃带，并在红外波段以热辐射方式释放热量，因此在韦伯望远镜影像中尘埃会发光。詹姆斯·韦伯望远镜上的中红外线仪器（MIRI）需要在-266ºC（相当于-447ºF）的极低温度下运行，否则它会探测到望远镜自身发出的红外线辐射。结合这些观测，天文学家得以把小尺度的气体与恒星连结到真正庞大的星系结构与演化尺度。
明日的图片: pixels in space
