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.
A blood cell, also called a hematocyte, is a cell produced by hematopoiesis and is normally found in blood. In mammals, these fall into three general categories: 1  Red blood cells â Erythrocytes. 2  White blood cells â Leukocytes. 3  Platelets â Thrombocytes.latelets, or thrombocytes or yellow blood cells, are very small, irregularly shaped clear cell fragments (i.e. cells that do not have a nucleus containing DNA), 2â3 Âµm in diameter, which derive from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days.