All the rage about water. From extrapolation made from the periodic table, H2O, or water, should freeze at lower temperatures. How would this affect the existence of life on Earth if water were to freeze at a much lower temperature? The water molecule has a high polarity, and because of this, water molecules stick together, thus making it harder for water to freeze at lower temperatures. Water is present in different forms in the Solar System, and, as we know, it is essential for life as we know it. Also, heavy water is present in different percentages in comets and asteroids. The percentage of heavy water on Earth matches the percentage of XXXXX, so scientists have concluded that the water on Earth comes from XXXXXX. 3 / 10,000 water molecules on Earth contain heavy water, but in a 1986 flyby of Halley's Comet, the ESA Giotto spacecraft found Halley contained a ratio of 6 / 10,000 heavy water molecules. So comets from the Kuiper Belt were ruled out as providers of Earth's water. From this, scientists concluded that most of Earth's water were delivered by asteroids, billions of years ago, in a period known as the Late Heavy Bombardment.