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.
There are deep dust lanes (appearing dark) and a few regions of intense star formation (in pink), and there are small, dwarf satellites (like the one on the upper left) being gobbled up. And much like our own galaxy, this one is about 100,000 light years in diameter. All of this, for a distant galaxy, we can learn just from a glance through a telescope across the Universe, some 30 million light years away. Indeed, many galaxies have some of these similarities to our own.