Download How do scientists know what stars and planets are made of?

How do scientists know what
stars and planets are made of?
Astronomy Unit
Earth Science
If we can’t go to other planets and
stars….
• All atoms and elements plus compounds like
to emit and absorb electromagnetic radiation
at different wavelengths.
• If you pass sunlight through a prism, the light
is bent so you can see all the different colors
of light that make up white light.
Wavelengths
• Each color of light has a different wavelength.
• Light can act like a particle and also like a
wave.
• Red light has longer wavelengths than violet
light (shorter wavelengths).
Well, what about stars?
• Scientists have studied the emission and
absorption spectra of different elements.
• Using a spectroscope, they can analyze the
light coming from a star and compare it to
known spectra from elements.
How else can scientists use this
information?
• Scientists can determine whether galaxies are
moving toward or away from the Milky Way.
• As a galaxy moves, it shifts the wavelengths of
light that are emitted.
• If the galaxy is moving away from us, the spectral
lines are shifted toward the red end of the
spectrum (redshift). If it is moving toward us, the
spectral lines are shifted toward the blue end of
the spectrum (blueshift).
• This is called the Doppler Effect.