This means that Eratosthenes estimated the circumference of the Earth to be about 40,000 km. He also knew that the circumference of a circle was equal to 2 times Ï (3.1415...) times the radius of the circle. (C = 2Ïr) With this information, Eratosthenes inferred that the Earth's radius was 6366 km.
Ankylosing spondylitis is a form of chronic inflammation of the spine and the sacroiliac joints. The sacroiliac joints are located at the base of the low back where the sacrum (the bone directly above the tailbone) meets the iliac bones (bones on either side of the upper buttocks) of the pelvis.
Ankylosing spondylitis is an inflammatory disease that affects the joints (called the sacroiliac joints) in the lower back in between the spine and pelvis. These joints over time often become swollen and inflamed. One potential complication of this condition is that the spinal bones can fuse together.nkylosing spondylitis is an inflammatory disease that affects the joints (called the sacroiliac joints) in the lower back in between the spine and pelvis. It is an inflammatory arthritis that particularly affects younger people, predominantly males, between the ages of 20 and 40.