The thymus is positioned in the upper chest cavity above the heart. Thymus. The thymus gland is the main organ of the lymphatic system. Located in the upper chest region, the primary function of this gland is to promote the development of specific cells of the immune system called T lymphocytes. T lymphocytes or T-cells are white blood cells that protect against foreign organisms (bacteria and viruses) that have managed to infect body cells.
How long does it take for the Earth to rotate on its own axis ? The time it takes the Earth to rotate once is called a day (24 hours). The actual rotation time is a little less, about 23 hours and 56 minutes. Why do we have Day and Night?
Most people know that the Earth revolves around the Sun in one year (actually. 365.24 days and we add one day to the calendar every four years, for a âleap. yearâ). Most also know that it takes 24 hours (actually 23 hours and 56 minutes) for the Earth to make a full rotation on its axis. Fewer people know that the Earthâs orbit is elliptical, or oval shaped, and that the Earth is sometimes slightly closer to the Sun than at other times, but this is not what causes the seasons, in fact we are closest to the Sun in January! Seasons are caused by the fact that the âEarth is tiltedâ (see Figure 1). What we mean by that is that the Earthâs axial tilt is at an angle of 23.5 degrees relative to the plane of the Ecliptic, its plane of orbit around the Sun. And the imaginary line, on which the Earth rotates, its axis, is tilted close to Polaris, the North Star.