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.
Image of the Milky Way taken at 1996. Texas Star Party. Our galaxy, the Milky Way, contains maybe 400 billion stars (plus or minus 200 billion) that lie mostly in a flattened spiral disk of some 70-100,000 light-years (ly) across, with a central bulge of about 10,000 ly in diameter.