What can Spectroscopy tell us

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Transcript What can Spectroscopy tell us

What Can Spectroscopy Tell Us?
Atom or Molecular Fingerprints
Every atom or molecule exists in its own unique energy state. This energy state is
dependent on the surrounding electron configuration. The energy state can be
increased (an electron moves to a higher energy level) by absorbing a photon (a
particle of light) or decreased by emitting a photon. The energy of an absorbed or
emitted photon is dependent on the discrete energy levels of the atom or molecule.
This produces a characteristic spectrum that acts as a fingerprint and allows us to
use spectroscopy to discover from what things are made. Go to this interactive to
play with an atom.
How do we use this information?
We can use this
information to
determine the
composition of distant
objects in the sky, such
as galaxies, stars,
planets, and nebula.
By using spectroscopy
we can determine what
elements are present in
the atmosphere of a
distant planet.
We are also able to determine the
relative abundance of each element.
In other words, it is possible to tell
how much of each element there is
relative to another.
Stellar Absorption and
determining Composition
This is a spectrum of the Sun. The dark bands are called absorption lines
and indicate different atoms present in the outer cooler layers of the Sun.
The pattern of the absorption lines allows astronomers to determine the
types of atoms and molecules that make up the star.
Click on the links below to find
the periodic table of elements
and their respective absorption
and emission spectra in the
visible portion of the spectrum.
We can also learn about the motion
of objects in space
Astronomers can use the Doppler shift to determine how fast a star is
moving towards or away from the Earth. By measuring the amount
that the spectra lines are shifted, we can determine how fast the Earth
and a star is approaching or receding from one another.
We can determine the temperature
The light emitted by a star
can be used to determine
its surface temperature.
Hotter objects have spectra
that peak at bluer
wavelengths while cooler
objects have spectra that
peak at redder
wavelengths. Click on the
Icon below to explore
blackbody radiation.