| 1 | There are also distinct, almost circular depressions of unknown origin near the foot of the flow. | |
| 2 | These are chains or rings of carbons atoms surrounded by hydrogen atoms. | |
| 3 | The green ring structure near the center of the image is about 77 light-years across. | |
| 4 | An atoll is a ring-shaped island that encloses a central lagoon. | |
| 5 | Topology: The different configurations that can be adopted in building networks, such as a ring, bus, star or meshed. |