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 arthritic condition that causes inflammation along the spine. If left untreated, the condition can cause the vertebrae to fuse together. When the vertebrae fuse, a personâs posture becomes hunched forward. Depending on the severity of these complications, crowding in the ribs can make it difficult for a person with ankylosing spondylitis to breathe. Inflammation is not always limited to the spine. Some people who have ankylosing spondylitis also experience inflammation around the eyes. The condition most commonly affects men, and symptoms are first noticed in early adulthood.