Mercury has shrunk more than scientists thought
Mercury is a planet. It is smaller now than it was when it formed.
Volume and temperature
Science
Grade 4
Air, water, and metal all grow bigger when they are warmed and smaller when they are cooled. A soap film or a dented ping-pong ball makes the change easy to see. If you test air, water, and metal in the same way, you find that the size of the change is different for each. Air changes the most, water comes next, and metal changes the least. Even when you cannot see it, things change size with temperature.