Two spiral galaxies touching arms. If you look closely at this week's space image, you can even spot a third galaxy.
The two largest galaxies are NGC 7733 (bottom right) and NGC 7734 (top left). These spiral galaxies are 500 million light-years from Earth and together form Arp-Madore 2339-661. The third small galaxy – NGC 7733N – lies directly above the upper spiral arm of NGC 7722 and is known for its orange-red gas clouds.
Galaxies affect each other. Just look at the area between the two systems, where the two arms appear to be converging. Here star-forming regions and gas clouds are compressed and deformed. In the future, the duo (or actually the trio) merges. This, of course, will take millions of years.
NGC 7733 and NGC 7734 both have a central bar and are therefore called barred spiral galaxies. The spiral arms of barred spiral galaxies — like our own Milky Way — come not from the center, but from the bar. Moreover, the two galaxies are different. NGC 7734 is round and its arms form two thin rings. NGC 7733 is flatter and the arms together form a single outer ring.
The image was taken using the Hubble Telescope, and it contains much more than just the galaxies mentioned above. Dozens of other galaxies can be seen much farther away than the trio.