Osteopenia refers to bone density that is lower than normal peak density but not low enough to be classified as osteoporosis. Bone density is a measurement of how dense and strong the bones are. If your bone density is low compared to normal peak density, you are said to have osteopenia.steopenia refers to bone density that is lower than normal peak density but not low enough to be classified as osteoporosis. Bone density is a measurement of how dense and strong the bones are. If your bone density is low compared to normal peak density, you are said to have osteopenia.
The Milky Way is the second-largest galaxy in the Local Group, with its stellar disk approximately 100,000 ly (30 kpc) in diameter, and, on average, approximately 1,000 ly (0.3 kpc) thick.
The M100 galaxy, which is about 60 percent larger than the Milky Way, next to the M97 galaxy. Think the Milky Way is big? It's puny compared to M87, an elliptical galaxy 980,000 light years in diameter. The Milky Way is only 100,000 light years in diameter. Let's not even get into Hercules A, which is 1.5 million light years across.