Mercury is the closest planet to the Sun, and it’s going through some big changes! Scientists have discovered that Mercury is getting smaller, and they’re trying to understand why this is happening.
In 2004, NASA sent a spacecraft called Messenger on an exciting journey to Mercury. After traveling for 1,260 days, Messenger finally arrived at Mercury and started taking pictures and collecting information. By 2012, Messenger had taken about 100,000 pictures, showing almost the entire surface of Mercury!
The pictures from Messenger showed some interesting things about Mercury’s surface. Scientists saw wrinkles and cracks that made the planet look a bit like a raisin. These features were first noticed by another mission called Mariner 10, and they show that Mercury is changing a lot.
One of the most surprising things scientists learned is that Mercury is shrinking! Over the last 4 billion years, Mercury’s diameter has gotten smaller by about eight miles. This is happening because Mercury’s core, which is mostly made of metal, is cooling down. The core makes up 85% of Mercury’s radius, so when it cools, the whole planet shrinks.
As Mercury’s core cools, the planet’s surface starts to contract, forming cracks and valleys. This is similar to how a grape shrinks and wrinkles when it dries into a raisin. The heat from the core escapes through the planet’s mantle, causing the surface to get smaller.
Mercury’s shrinking is an exciting part of learning about planets and how they change. By studying the data from the Messenger mission, scientists are discovering more about Mercury’s past and what happens when a planet’s core cools down. This helps us understand more about our solar system and the amazing processes that shape it.
Modeling Planetary Shrinkage: Create a simple model to demonstrate how Mercury shrinks. Use a balloon to represent Mercury. Inflate the balloon and draw lines on it with a marker to represent the planet’s surface. Slowly deflate the balloon and observe how the lines wrinkle and come closer together, similar to how Mercury’s surface changes as it shrinks. Discuss with your classmates how this activity relates to the shrinking of Mercury.
Temperature and Material Changes: Explore how temperature affects materials by conducting a simple experiment. Take a piece of chocolate and observe its state at room temperature. Then, place it in a warm area or under a lamp and watch how it changes. Discuss how this change is similar to Mercury’s core cooling and causing the planet to shrink. What happens to the chocolate when it cools down again?
Observation and Drawing: Go outside and find a natural object, like a leaf or a rock, that has cracks or wrinkles. Draw a picture of it and describe what you see. Think about how these features might have formed. Compare your observations to the pictures of Mercury’s surface from the Messenger mission. How do natural processes on Earth help us understand changes on other planets?
