Our Solar System
Infrared spectroscopy has provided valuable information about the composition of planets, planetary atmospheres, moons, comets and asteroids. For example, water has been detected in the atmospheres of the giant gas planets and Saturn's moon Titan. In addition, hydrocarbons have been detected on Jupiter and Saturn. Recently, infrared spectra revealed evidence that the planets Uranus and Neptune have large icy cores and that Mars had an early and long term presence of carbon which is one of the requirements for life.
Comets, which are made up of ice, dust and organic solids, contain the original interstellar material from which our solar system formed. Studying comet composition can help us learn about the formation of our solar system as well as other stellar systems. The infrared spectrum of a comet consists of spectral features superimposed on a continuum due to dust. Below 3 microns, this continuous spectrum is the result of sunlight reflected by the comet's dust. Above 3 microns the continuum is due to the thermal emission of the dust itself which depends on the dust temperature. So far, infrared spectroscopy has identified several molecules in comets including silicates (10 microns), water (2.7 microns), carbon monoxide (4.7 microns), CH3OH (3.52 microns), carbon dioxide (4.25 microns), and H2CO (3.59 microns).
To learn more about the infrared detection of ices in our solar system click here. For a list of atoms and molecules identified in comets click here.