Spectroscopy
Spectroscopy is a very important tool in astronomy. It is
detailed study of the light from an object. Light is energy that moves
through space and can be thought of as either waves or particles. The
distances between the peaks of the waves of light are called the light's
wavelength. Light is made up of many different wavelengths. For example,
visible light has wavelengths of about 1/10th of a micrometer - ten thousand
wavelengths would be the width of a dime.
Spectrometers are instruments which spread light out into
its wavelengths creating a spectra. Within this spectra, astronomers can
study emission and absorption lines which are the fingerprints of atoms and
molecules. An emission line occurs when an electron drops down to a lower
orbit around the nucleus of an atom and looses energy. An absorption line
occurs when electrons move to a higher orbit by absorbing energy. Each atom
has a unique spacing of orbits and can emit or absorb only certain energies
or wavelengths. This is why the location and spacing of spectral lines is
unique for each atom.
Astronomers can learn a great deal about an object in
space by studying its spectrum, such as it's composition (what its made of),
temperature, density, and it's motion (both it's rotation as well as how
fast it is moving towards or away from us).
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