가장 희귀한 은하 유형인 고리 은하가 마침내 이해되었습니다.

When we look out into deep space, beyond the confines of the Milky Way, we find that the Universe isn’t quite so empty. An enormous variety of galaxies fill the abyss of space: small and large, near and far, in rich clusters and in near-total isolation. The Milky Way itself represents just one of at least two trillion such galaxies (and probably several times as many) within the observable Universe. Galaxies are collections of both dark matter and normal matter, where the latter includes plasmas, gas, dust, planets, black holes, and — most prominently — stars. After all, it’s through the examination of that starlight that we’ve learned the most about the physical properties of galaxies, and been able to reconstruct how they came to be.
In general, there are four classes of galaxies that we see.

Spirals, like the Milky Way, are the most common type of large galaxy in the Universe.
Ellipticals, like M87, are the largest and most common type of gala