Exploring Density main content.

Exploring Density

The Arthur Ross Hall of Meteorites

Educator's Guide: Activity


In the early solar nebula, particles clumped together, building up into larger and larger bodies. These objects repeatedly crashed into each other as they orbited the sun, shattering them or compacting them. The planets and larger asteroids began to melt and differentiate. Dense metal material sunk to the core. Silicate material formed the mantle. Further heating of the mantle caused the crust to form.

Resource Use

The activity Exploring Density is designed to help students understand the concept of differentiation. When planets differentiate, dense materials sink; lighter materials float.

Have students determine the density of marshmallow fluff and molasses by filling identical beakers to the same level with each material and weighing both beakers. Then, place a dome of marshmallow fluff in the bottom of a clear bowl. Have students thin out fluff near edges and add molasses until it is about 3" deep. Ask students to predict what will happen and why. Then, observe what happens. Which material ends up on top? Why? Discuss the results with students and have them draw conclusions about why dense material is at the core of differentiated planets.