Final answer:
Standing water forms on Earth when precipitation accumulates due to topographical features, impermeable surfaces, or saturation, which prevents water from draining or evaporating. Earth's water is ancient, but the water cycle continually replenishes standing bodies of water. The origin of Earth's water may include interstellar sources, planetary formation, and cometary impacts.
Step-by-step explanation:
Standing water on Earth forms when precipitation from the water cycle accumulates in areas where it cannot readily drain away or evaporate. This occurs due to various reasons, such as the topography of the land, presence of impermeable surfaces, or a high water table. When it rains, water infiltrates the ground to a certain extent, but if the ground is saturated or there is a lack of proper drainage, standing water can form in low-lying areas creating ponds, lakes, or wetlands.
Over time, standing bodies of water can also result from geological features, like a line on Earth's surface that results from a deep crack in the crust, which acts as a natural basin for water accumulation. Furthermore, the original source of Earth's water could be interstellar, with the planet’s oceans and lakes potentially originating from water locked into the rocky material that formed Earth, or via cometary impacts during its formative years.
Water on Earth is constantly in flux, with molecules moving through the global water cycle, changing states between liquid, vapor, and ice. This process shapes our planet's hydrosphere, ensuring that while the water itself is ancient, the standing bodies of water are dynamic and constantly being replenished through various means such as rain, groundwater movement, and melting ice.