http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=sloan
http://www.worldwidetelescope.org/thumbnails/sloan.png
H
H
H
H
H
H
This blue star's spectrum shows absorption lines
produced by Hydrogen in the star's atmosphere.
Blue Star
http://www.worldwidetelescope.org/thumbnails/sloan.png
This red star's spectrum shows absorption bands
produced by molecules in the star's atmosphere.
Red Star
http://www.worldwidetelescope.org/thumbnails/sloan.png
H
H
H
H
H
H
H
The Hydrogen absorption lines in this white dwarf spectrum
are broadened by the star's huge surface gravity.
White Dwarf
http://www.worldwidetelescope.org/thumbnails/sloan.png
Ca
H
Mg
Na
The spectrum of this Elliptical Galaxy is composed of hundreds of billions of stars.
We can easily identify absorption from Calcium, Hydrogen, Magnesium and Sodium.
The redshift indicates that it is 140 million light years from us.
Elliptical Galaxy
http://www.worldwidetelescope.org/thumbnails/sloan.png
S
N
O
O
H
The spectrum of this Dwarf Galaxy shows emission lines
produced by hot Oxygen, Hydrogen, Nitrogen and Sulfur gas.
Blue Dwarf Galaxy
http://www.worldwidetelescope.org/thumbnails/sloan.png
Ca
N
S
O
Mg
H
In Spiral Galaxies we see both emission lines from gas and absorption lines from stars.
The redshift of this galaxy indicates that it is 450 million light years from Earth.
Spiral Galaxy
http://www.worldwidetelescope.org/thumbnails/sloan.png
C
C
Mg
Quasar spectra show broad emission lines. These lines are produced
by fast moving gas clouds near the supermassive black hole at
the center of the Quasar. This Quasar is 5.75 billion light years distant.
Quasar
http://www.worldwidetelescope.org/thumbnails/sloan.png
H
The bright line in the red has been redshifted all the way from the ultraviolet
in this distant Quasar.The dark bands blueward of that line are produced by
gas clouds between us and the Quasar which is 25 billion light years away.
Distant Quasar
http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=114236925
http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=114236925
Kirchhoff's Laws of Spectroscopy
Nineteenth century physicist Gustav Kirchhoff formulated
three laws describing the spectral composition of light.
http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=114236925
Kirchhoff's First Law
A hot object produces light with a continuous spectrum.
http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=962869576
Kirchhoff's Second Law
A hot tenuous gas produces a spectrum with bright lines at specific colors.
http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=549595493
Kirchhoff's Third Law
A hot object surrounded by cooler tenuous gas (like a star)
produces a continuous spectrum with dark absorption lines.
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