Microorganisms causing diseases that characteristically are waterborne prominently include protozoa and bacteria, many of which are intestinal parasites, or invade the tissues or circulatory system through walls of the digestive tract. Various other waterborne diseases are caused by viruses.
As the Moon revolves around Earth, both objects also progress in orbit around the Sun. After completing one revolution with respect to the stars, the Moon must continue a little farther along its orbit to catch up to the same position it started from relative to the Sun and Earth.
Viewed from Earth, the Moon appears to rock slowly backwards and forwards so that we see a slightly different face throughout the lunar month. There are two main reasons for this. First, the Moonâs orbit around Earth is elliptical not circular so its rotation is sometimes ahead, and sometimes behind, its orbital motion. And second, the Moonâs rotation axis is not at right angles to its orbit around the Earth so we can sometimes see âoverâ or âunderâ its poles. Over time this means we actually get to see about 59 per cent of the Moonâs surface.