the electromagnetic spectrum in our universe. background info. ★ everything astronomers know about...
TRANSCRIPT
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
long waves
short waves
Which have the highest energy?
•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)
Spectroscopy
Emission spectrum of Hydrogen, H
Emission spectrum of Iron, Fe
•optical telescopes, radio and x-ray telescopes are used to collect data
xray telescope
radio telescope
•The Doppler Effect is used to determine if a galaxy is moving away from or towards earth
The Expanding Universe
Compare red and blue visible Compare red and blue visible light...light...Does red have a long or short Does red have a long or short wavelength?wavelength?Does blue have a long or short Does blue have a long or short wavelength?wavelength?
Electromagnetic SpectrumElectromagnetic Spectrum
•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
If we could see the sound waves, what color would they be?
draw this
If a galaxy is moving toward If a galaxy is moving toward earth, is it earth, is it blueblue or or redred??
If a galaxy is moving away from If a galaxy is moving away from earth, is it earth, is it blueblue or or redred??
•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 LawHubble’s Law
•Distant galaxies are moving away Distant galaxies are moving away from each other faster than those that from each other faster than those that
are closer togetherare 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