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 light... Does red have a long or short wavelength? Does blue have a long or short wavelength? Electromagnetic 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 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 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