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.
If the whole galaxy were bright enough, this is what youâd see at night (with the moon as a reference) 1 : Huge! And given that itâs 2.5 million light years away, the surprising amount of sky space Andromeda takes up speaks to just how ridiculously large a 140,000 light year diameter galaxy is. Hereâs one more delicious composite photo that shows the relative size Andromeda would be in the sky, courtesy of NASA :