1. Density In the solar system

2. Density on Earth Density of water 1.0 g/cm 3 Density of air 0.0012 g/cm 3 (sea level at 15° C) Changes in temperature, humidity and salinity can change the density of water and air

3. Density on Earth Metamorphic rocks Sedimentary rocks Igneous rocks Density of rocks 2.2-3.3 g/cm 3

4. Density of Earth Average Density 5.5 g/cm 3

5. Density of Earth Density is one of the clues geologists have used to help understand the internal structure of Earth

6. Inside Earth Seismic waves from earthquakes passing through Earth provide important information about the size and characteristics of each layer.

7. 15 10 5 Density g/cm 3 Inside Earth Using these and other pieces of evidence, geologists have been able to create a model of Earth’s internal structure.

8. Inside Earth Seismic waves from earthquakes passing through Earth provide important information about the size and characteristics of each layer. Inner Core Outer Core Mantle

9. The mass and volume of Earth are much larger than the mass and volume of the Moon. Comparison of Earth and Moon What about density?

10. Earth Average Density 5.5 g/cm 3 Moon Average Density 3.4 g/cm 3 What can we infer about the composition and internal structure of the Moon based on its density compared to Earth? Comparison of Earth and Moon What about density?

11. Mercury vs. Ganymede Average Density 5.43 g/cm 3 Average Density 1.94 g/cm 3 Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington Credit: NASA

12. Mercury vs. Ganymede Average Density 5.43 g/cm 3 Average Density 1.94 g/cm 3 Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington Credit: NASA What can we infer about the compositions of Mercury and Ganymede based on their densities?

13. Mercury vs. Ganymede Rock surrounding a large iron core Image courtesy of Windows to the Universe Credit: NASA Icy shell surrounding a small rocky mantle and small metallic core

14. 1 Ceres Diameter = 606 miles 4 Vesta Diameter = 348 miles The DAWN spacecraft will determine the mass of Vesta and Ceres by measuring each asteroid’s gravity. Vesta arrival: July, 2011 Vesta departure: September, 2012 Ceres arrival: February, 2015 http://dawn.jpl.nasa.gov/ Calculating average density using the mass will give us information about their internal structure