Transcript All these different energies are classified according to wavelength

The Electromagnetic
Spectrum in our
Universe
Background info.
★Everything astronomers know
about the universe comes from
studying light from distant stars and
nebula.
★The universe is full of energy,
visible and invisible, all of these
different energies are called
electromagnetic radiation.
Background info.
★All these different energies are
classified according to wavelength
and frequency.
★This info. is displayed as the
Electromagnetic Spectrum.
Background info.
How do we know this?
Instruments detect their
presence.
Electromagnetic Spectrum
draw this
Sir Isaac Newton discovered that when light passes
through a prism, the different colors of light are broken
up.
each color has its own wavelength
So...what’s a rainbow?
• Speed of light: 300,000 km/sec or
186,000 mi/sec
• Visible light only makes up a small
part of different types of energy
known as electromagnetic radiation
• Gamma waves and radio waves are
different due to their wavelengths
short
waves
long
waves
Which have the highest energy?
Spectroscopy
• study of the properties of light that
depend on its wavelength
• when the light of a star is studied
there are spectral lines
• the spectral lines act as a
“fingerprint” that helps to identify the
elements inside the star (a star’s
chemical composition)
Emission spectrum of Hydrogen, H
Emission spectrum of Iron, Fe
• optical telescopes, radio and x-ray
telescopes are used to collect data
radio telescope
xray telescope
The Expanding
Universe
• The Doppler Effect is used to
determine if a galaxy is moving
away from or towards earth
Electromagnetic Spectrum
Compare red and blue visible light...
Does red have a long or short
wavelength?
Does blue have a long or short
wavelength?
• Doppler Effect works with sound
waves and light waves
the siren in front of
the cop car has a
high pitch, but
behind the car it has
a low pitch sound
draw this
If we could see the sound waves, what color
would they be?
If a galaxy is moving toward earth, is it
blue or red?
If a galaxy is moving away from earth,
is it blue or red?
• 1929 Edwin Hubble discovered
that the universe is expanding
• galaxies are moving away
because they appear red ( the
waves are stretched out)
• most of the galaxies we see have
a Red Shift
• Hubble’s Law: galaxies are moving
away from earth at a speed that is
proportional to their distance
Hubble’s Law
•Distant galaxies are moving away from each
other faster than those that are closer
together
as the dough rises, raisins that
were farther apart travel a greater
distance in the same time as those
that were closer together, raisins
are like galaxies in an expanding
universe
Review #1Which EM waves are
long and stretched out?
๏radio waves
Review #2 What color
waves are long and
stretched out?
๏red waves
Review #3Which EM waves
are short and squished?
๏gamma rays
Review #4What color
waves are short and
squished?
๏violet waves
Review #5 What information is found
by looking at the spectral lines from a
star’s gases?
๏which elements are in the star
(chemical composition)
Review #6 What is happening to
the size of the universe?
๏universe is expanding
Review #7 What kind of shift
is responsible for this?
๏Red shift
Review #8 What does Hubble’s
Law explain?
๏galaxies are moving away at a
speed that is proportional to their
distance