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.
So in 90 seconds, for example, we all move some 20,000 kilometers â or 12,500 miles â in orbit around the galaxyâs center. Our Milky Way galaxy is a big place. Even at this blazing speed, it takes the sun approximately 225-250 million years to complete one journey around the galaxyâs center.