The Ice That's Hotter Than The Sun

round us which we take as a given. We know that gravity makes things drop down towards the ground. We see that birds always poop on a freshly waxed car. And we know that water turns into solid ice when it is cooled below freezing point. But is this last observation always true? Can ice be warm? Can ice be a liquid? Can you really build a hot snowman? How can ice be hot? If you were to heat up an ice cube in a bowl you’d be left with a delicious water soup, would you not? Wait, hang on. We missed out an important detail. Ice does not have to be cold. It’s true, and to explain why, let’s look at how ice is formed here on regular old Earth. If you paid attention in school for anything more than five minutes, you should know that each water molecule consists of two hydrogen atoms and one water atom - hence the name H2-oh-MyGodThat’sRefreshing. Now, when water molecules are sat in liquid form it’s because they possess more energy than they do when they’re solid. Like a room full of hyperactive toddlers, the water molecules run around bouncing off one another when they’re pumped full of fun juice. Cool that water down a little and the molecules move a little slower. Cool it down towards freezing point and they won’t stop altogether, but they will slow down so much that they appear to be stuck in a rigid form. Weirdly, when water is frozen at zero degrees, it is actually less dense than liquid water. The reason for this is that as you head towards freezing point the water molecules begin forming a solid, hexagonal crystalline structure, with the hydrogen atoms of one

molecule bonding weakly with the top of the oxygen atoms of two other water molecules. This pattern takes up more space than the jumbled up arrangement of liquid water since there’s lots of empty space between the molecules, and this causes the water to expand as it forms ice. But in exchange for the restricted legroom, you do get to look at a bunch of delightfully pretty water crystals. You need around 275 individual water molecules to form the beginning of an ice crystal, and 475 to make a fully formed crystal of ice. The colder you freeze ice beyond four degrees Celsius the less dense it becomes, and although ice can start to become more dense when you reach extreme temperatures, it still won’t ever be as dense as it was in its liquid form - even if you squash it. Now if we’re still using the room full of toddlers analogy things become rather grim when we talk about crushing them all together.