Chromaffin cell. Chromaffin cells, also pheochromocytes, are neuroendocrine cells found mostly in the medulla of the adrenal glands (located above the kidneys) in mammals.
The elements sodium (Na) and potassium (K) have been detected in the Moon's atmosphere using Earth-based spectroscopic methods, whereas the isotopes radon -222 and polonium -210 have been inferred from data obtained by the Lunar Prospector alpha particle spectrometer.
Orbit of the Moon. The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in approximately 27.323 days (a sidereal month). Earth and the Moon orbit about their barycentre (common center of mass), which lies about 4,600 km (2,900 mi) from Earth's center (about 34 of the radius of Earth). On average, the Moon is at a distance of about 385,000 km (239,000 mi) from Earth's centre, which corresponds to about 60 Earth radii.