The universe is vast, with galaxies containing gas, dust, stars, and planets sprinkled throughout. But this sprinkling isn’t random; although some galaxies are indeed truly alone, most are not congregating through gravity.
NGC 1706, captured in this stunning Hubble Space Telescope image, is one of about 50 galaxies bound together in a group that lies in the direction of the southern constellation Dorado the Swordfish. The brilliant, face-on spiral and its neighbors sit about 230 million light-years away.
The universe itself is expanding, but galaxies can still exert gravity on each other. If you were to take a step back and view the universe from outside, you’d see that galaxies form clumps and strings, while leaving voids of vast nothingness in between.
About half of all galaxies can be found in some sort of grouping — in fact, galaxies and galaxy groups are the visible signposts marking what astronomers call ...
