关于这张图
In this image the NASA/ESA Hubble Space Telescope takes a close look at the spiral galaxy NGC 4217, located 60 million light-years away from Earth. The galaxy is seen almost perfectly edge on and is a perfect candidate for studying the nature of extraplanar dust structures — the patterns of gas and dust above and below the plane on the galaxy, seen here as brown wisps coming off NGC 4217. These tentacle-like filaments are visible in the Hubble image only because the contrast with their surroundings is so high. This implies that the structures are denser than their surroundings. The image show…