The most common way to become infected with giardia is after swallowing contaminated water. Giardia parasites are found in lakes, ponds, rivers and streams worldwide, as well as in municipal water supplies, wells, cisterns, swimming pools, water parks and spas.
Andreas Cellarius's illustration of the Copernican system, from the Harmonia Macrocosmica (1708). Heliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around the Sun at the center of the Solar System. The word comes from the Greek (á¼¥Î»Î¹Î¿Ï helios sun and ÎºÎ­Î½ÏÏÎ¿Î½ kentron center).
closed universe - (cosmology) a universe that is spatially closed and in which there is sufficient matter to halt the expansion that began with the big bang; the visible matter is only 10 percent of the matter required for closure but there may be large amounts of dark matter.