Density In the solar system
Density on Earth Density of air 0.0012 g/cm3 (sea level at 15° C) Density of water 1.0 g/cm3 Changes in temperature, humidity and salinity can change the density of water and air
Density on Earth Igneous rocks Density of rocks 2.2-3.3 g/cm3 Sedimentary rocks Metamorphic rocks
Density of Earth Average Density 5.5 g/cm3
Density of Earth Density is one of the clues geologists have used to help understand the internal structure of Earth
Inside Earth Seismic waves from earthquakes passing through Earth provide important information about the size and characteristics of each layer.
Inside Earth Using these and other pieces of evidence, geologists have been able to create a model of Earth’s internal structure. 15 10 5 Density g/cm3
Inside Earth Inner Core Outer Core Mantle Seismic waves from earthquakes passing through Earth provide important information about the size and characteristics of each layer.
Comparison of Earth and Moon The mass and volume of Earth are much larger than the mass and volume of the Moon. What about density?
Comparison of Earth and Moon What can we infer about the composition and internal structure of the Moon based on its density compared to Earth? Moon Average Density 3.4 g/cm3 What about density? Earth Average Density 5.5 g/cm3
Mercury vs. Ganymede Average Density 5.43 g/cm3 Average Density 1.94 g/cm3 Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington Credit: NASA
Mercury vs. Ganymede What can we infer about the compositions of Mercury and Ganymede based on their densities? Average Density 5.43 g/cm3 Average Density 1.94 g/cm3 Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington Credit: NASA
Mercury vs. Ganymede Rock surrounding a large iron core Icy shell surrounding a small rocky mantle and small metallic core Image courtesy of Windows to the Universe Credit: NASA
The DAWN spacecraft will determine the mass of Vesta and Ceres by measuring each asteroid’s gravity. Calculating average density using the mass will give us information about their internal structure 1 Ceres Diameter = 606 miles 4 Vesta Diameter = 348 miles Vesta arrival: July, 2011 Vesta departure: September, 2012 Ceres arrival: February, 2015 http://dawn.jpl.nasa.gov/