Asteroids are celestial rocky bodies that orbit the sun. It was Sir William Herschel who first coined the term âasteroidâ (Greek for star-like) in 1802. He thought that Ceres and Pallas, discovered in 1801 by Giuseppe Piazzi and Heinrich Olbers respectively, were too small and were remnants of a destroyed planet.
blood cell. n. Any of the cells contained in blood; an erythrocyte or leukocyte; a blood corpuscle. blood cell. n. (Physiology) any of the cells that circulate in the blood. See erythrocyte, leucocyte.
White blood cells. Blood cells that help fight infection and other diseases. An important part of the body's immune system, white blood cells (WBCs) are made in the bone marrow (the soft, sponge-like tissue in the center of most bones). White blood cells are classified according to their structure and function. Two of the most common types are lymphocytes and neutrophils. A low WBC count is called leukopenia. A high WBC count is called leukocytosis. White blood cells are also called leukocytes.