#### Transcript EM Spectra and Stars Power Point

```Spectra and
Stars
How do colors in
a spectrum help
us understand
stars?
Image from
a.jpg
www.cpalms.org
We can’t go to stars and planets
to see what they are like.
Deep space image from
by studying the light that they emit or reflect.
www.cpalms.org
what evidence do you have that we can learn
something about stars from their light?
2. From Activity 2 about using c-spectra and colored
. filters…….
3. From Activity 3 about light from a hot gas………
www.cpalms.org
NASA: Spectroscopy in Action PLAY VIDEO
www.cpalms.org
The color of light is the wavelength.
Visible light ranges in wavelength from ~400 to ~700 nanometers.
But visible light is only a small part of the
electromagnetic spectrum.
Image from http://science.hq.nasa.gov/kids/imagers/ems/visible.html
www.cpalms.org
Light is energy ……..
energy travels in waves........
waves have properties!
Waves only transfer energy without the physical movement
of material from one location to another.
Light travels through space at 300,000,000 m/s.
One property of a wave is the wavelength – the distance
between successive wave peaks.
Electromagnetic waves are transverse waves.
Image
from
www.cpalms.org
Light travels as a wave in an infinite
The range of all possible
frequencies
of electromagnetic
the electromagnetic
spectrum.
The wavelength of an EM wave is inversely proportional to its
frequency and also to it’s energy.
The shorter the wavelength, the higher the frequency and the
more energy the wave has.
Image from http://en.wikipedia.org/wiki/Microwave#mediaviewer/File:EM_spectrum.svg
www.cpalms.org
CONTINUOUS
SPECTRUM
Light is separated into its various wavelengths using a
piece of glass called a prism.
A rainbow is an example of continuous spectrum.
Image from
http://commons.wikimedia.org/wiki/File:Spectral_lines_continous.png
Another Image that shows the experiment can be viewed at
http://astronomy.nju.edu.cn/~lixd/GA/AT4/AT404/HTML/AT40401.htm
www.cpalms.org
EMISSION
& ABSORPTION
SPECTRUM
Occur when the light coming from a gas is passed through the surfaces
of a prism or c-spectra. Depending on whether or not the gas cloud is in
front of a blackbody object, the spectrum will either be an
emission line spectrum or an absorption line spectrum.
Image from
http://commons.wikimedia.org/wiki/File:Visible_spectrum_of_hydrogen.j
pg
Another Image that shows the experiment can be viewed at Image from
http://astronomy.nju.edu.cn/~lixd/GA/AT4/AT404/HTML/AT40401.htm
www.cpalms.org
Different Types of Spectra
Each element has different emission lines which show the
same colors that are missing in the absorption line.
Image from http://commons.wikimedia.org/wiki/File:Visible_spectrum_of_hydrogen.jpg and Image
from http://commons.wikimedia.org/wiki/File:Spectral_lines_continous.png
Another Image that shows a comparison can be viewed at
http://www.extremetech.com/extreme/167878-every-color-of-the-suns-rainbow-why-arewww.cpalms.org
there-so-many-missing
Each atom of a given element
is unique and has unique properties,
including what kind of color is emitted when it’s heated.
Images from http://commons.wikimedia.org/wiki/File:Periodic_table_large.png
www.cpalms.org
Hydrogen
Emission Spectrum
Absorption Spectrum
Image from http://commons.wikimedia.org/wiki/File:Visible_spectrum_of_hydrogen.jpg
What is the difference between Emission and Absorption Spectra?
The emission lines emit the color / wavelength.
Absorption lines absorb the same color / wavelength.
www.cpalms.org
Identifying Absorption Lines of a Star
spectrum-hubble-telescope.jpg
www.cpalms.org
Sun’s Absorption Spectrum
Black lines are caused by gases on, or above, the Sun’s surface that
absorb some of the emitted light.
Image from http://www.extremetech.com/extreme/167878-every-color-of-the-suns-rainbow-why-are-there-so-many-missing
The Mystery????
Some lines are not identified.
Are they produced by elements that don’t exist on Earth?
www.cpalms.org
Ultraviolet Image of the Sun
Ultraviolet
(UV) light
waves are
invisible to
the human
eye.
Image from
http://missionscience.nasa.gov/ems/10_ultravioletwaves.html
www.cpalms.org
If we change
the detector,
we can ‘see’
these shorter
wavelengths.
X-ray Image of the Sun
X-ray detectors are
used by scientists
to see and record
the energy within
the corona.
Data was collected
by x-ray detectors
on satellites in orbit
around the Earth
by the Japan's
Hinode spacecraft.
Image from
http://missionscience.nasa.gov/images/ems/emsXRays_mainContent_xraysun.png
www.cpalms.org
Different Types of Telescopes and Detectors
Used to study the light from planetary images and satellite imagery.
First telescope - Galileo in 1609. The eye detects visible light only.
Radio telescopes - detects the very longest wavelength of light.
Space Telescopes - detects different wavelengths, like X-ray,
ultraviolet and infrared.
Space Telescopes - operate in space to avoid the obscuring
effects of our atmosphere.
Hubble Space Telescope - Optical
Spitzer Infrared Observatory