Silicates in Alien Asteroids

This plot of data from NASA's Spitzer Space Telescopes shows that asteroid dust around a dead "white dwarf" star contains silicates—a common mineral on Earth. The data were taken primarily by Spitzer's infrared spectrograph, an instrument that breaks light apart into its basic constituents. The yellow dots show averaged data from the spectrograph, while the orange triangles show older data from Spitzer's infrared array camera. The white dwarf is called GD 40.