Incredible ice
We know that it’s solid water, but that’s just the tip of the iceberg
There’s a lot more to solid water than meets the eye
Our ‘blue planet’ is famed for its expansive oceans and salty seas, but approximately ten per cent of our planet’s surface is frozen over. The vast majority of this ice is found in the polar regions. The Antarctic ice sheet covers an area about the size of the United States and Mexico combined. Meanwhile, in the North Pole, the Greenland ice sheet is so heavy that it presses the land below into a concave bowl shape. Because of its brightwhite colouration, ice reflects sunlight back into the atmosphere. This process plays a crucial role in regulating Earth’s climate.
But icy worlds also exist beyond our own planet. When NASA’S MESSENGER mission glimpsed bright spots at Mercury’s poles, scientists theorised that water ice could be hiding inside the planet’s deep, sunless craters.
Ice is simply the solid state of liquid water, forming at temperatures of zero degrees Celsius or below. Its chemical composition is two hydrogen atoms bonded to a single oxygen atom – also known as water.
When water is cooled to a low temperature, bonds form between different water molecules very easily. This forces water into a crystal lattice structure of many layers of hexagonal rings. Most elements are less compact in their liquid state. However, the unique hexagonal structure of ice crystals is filled with more gaps than the disordered fluid structure of water, meaning ice is about ten per cent less dense than water.
It is this phenomenon that allows ice to float – either in the form of gigantic icebergs travelling across the Arctic Ocean or ice cubes in a refreshing drink on a hot day. In fact, ice’s cooling properties are very handy. Before we had electric refrigerators, ice boxes were used to keep food cold and fresh. Ice can also reduce swelling and pain by reducing blood flow to injured body parts.
“Because of its bright-white colouration, ice reflects sunlight back into the atmosphere”