How to Measure the Density of a Planet

You can find the density of any planet with a simple calculation.
••• forplayday/iStock/Getty Images

The physical density of any object is simply its mass divided by its volume; density is measured in units such as pounds per cubic foot, grams per cubic centimeter or kilograms per cubic meter. When calculating the density of a planet, look up its mass and radius, the latter of which is the distance from the surface to the center. Because planets are roughly spherical, calculate the volume of a sphere using the radius. Then divide the mass by the volume of the sphere to get the density.

    Find the planet’s mass and diameter. For example, Earth’s mass is about 6,000,000,000,000,000,000,000,000 kg and its radius measures 6,300 km.

    Enter the radius in the calculator. Multiply by 1,000 to convert kilometers to meters. Cube this number by pressing the "x^3" key; alternatively, you can press the "x^y" key, enter the number three and then press "equals." Multiply by the number pi -- or 3.1416 -- multiply by four and then divide by three. Store the result by pressing the "M+" or other memory key. The figure you see is the planet’s volume in cubic meters. To continue the example, 6,300 km times 1,000 meters/km = 6,300,000 meters. Cubing it gives 250,000,000,000,000,000,000. Multiplying by pi times 4/3 yields 1,047,400,000,000,000,000,000 cubic meters.

    Key the planet’s mass into the calculator. Press the divide key, then recall the volume figure stored in the calculator’s memory. Press the equals key. This result is the planet’s density in units of kilograms per cubic meter. In our example, dividing 6,000,000,000,000,000,000,000,000 kg by 1,047,400,000,000,000,000,000 cubic meters results in a density of about 5,730 kg per cubic meter.

    Tips

    • If you have the planet’s diameter instead of its radius, divide it by two to get the radius.

Related Articles

Orbital Radius vs. Planetary Radius
How to Find the Radius of a Sphere When Given the Volume
What Is the Average Temperature of Jupiter?
How to Calculate the Mass of a Solid
What Are the Elements of Uranus?
How to Calculate the Moment of Inertia
How to Figure the Cubic Yards in a Circle
Which Planet Apparently Shrank in Diameter?
How to Solve Gravitational Force Problems
How to Calculate Volume From Centimeters
How to Find the Volume of a Sphere in Terms of Pi
How to Convert XY Coordinates to Longitude and Latitude
How to Convert ML to MG
Are the Sun & Moon Planets?
How to Compare Earth to Neptune
How to Calculate Your Weight on the Moon
How to Calculate the Volume and Circumference of a...
How to Find and Calculate the Weight of a Sphere
How to Calculate Sphere Size
How to Convert Grams Per Meter Squared to Pounds Per...

Dont Go!

We Have More Great Sciencing Articles!