1. 8.5CD Electromagnetic Spectrum and Light Years The student is expected to explore how different wavelengths of the electromagnetic spectrum such as light and radio waves are used to gain information about distances and properties of components in the universe. And model and describe how light years are used to measure distances and sizes in the universe.

2. Electromagnetic Spectrum-EMS A range of all types of electromagnetic radiation, from very long wavelengths, radio and microwaves, to very short wavelengths, such as x-rays and gamma rays.

3. Radiation Energy that can travel through the vacuum of space. We call all forms of electromagnetic radiation “light.”

4. EMS Rosa’s Mom Invited Very Ugly Xmas Guests. There are many types of electromagnetic radiation, and they all travel in waves. Scientists use wavelength to classify electromagnetic radiation. Wavelength is measured from the trough (or very bottom) of one wave to the trough of the next wave, or the crest (or very top) of one wave to the next wave.

5. Electromagnetic Radiation All types of electromagnetic radiation travel at about the same speed of 300,000,000 mps. We call this the “Speed of Light.” In addition to speed and wavelength, electromagnetic waves can be measured by frequency. Frequency refers to the number of waves that pass a fixed point in a time frame, such as a second. Which will have a higher frequency, the shorter wavelengths, such as gamma rays, or the longer wavelengths, such as radio waves?

6. Frequency-turn to the EMS handout you glued into your notebook. The shorter wavelengths have higher frequencies because more waves will travel past a point within a given time frame. Ultraviolet, x- ray, and gamma ray radiation are the most dangerous.

7. Visible Light Visible light is the only part of the electromagnetic spectrum that humans can see.

8. Visible Light Visible light is radiated as white light, which is made up of different wavelengths of radiation, from about 400–700 nanometers (nm). Different wavelengths corresponds to a different color. We see the longest wavelengths of visible light as red light. We see the shortest wavelengths as violet light. White light can be separated into different colors using a special lens called a prism. A raindrop acts as a prism when we see a rainbow.

9. Visible Light- During the Explore Activity, we used glasses that acted as a prism to divide light into its different colors. To help you remember the visible light spectrum from longest wavelengths to shortest wavelengths, we use the following mnemonic device. Use red for R, orange for O, etc. ROY G BIV

10. Using light to determine the position of the stars In order to calculate how far away a star is, astronomers use a method called parallax. Because of the Earth's revolution about the sun, near stars seem to shift their position against the farther stars. This is called parallax shift. Stars that are closer to Earth will appear to shift more throughout the year than stars that are further away.

11. Using the EMS to understand the universe Most of our knowledge about the universe comes from observations of visible light. We use telescopes to view distant objects in space. Even though electromagnetic radiation travels faster than anything else in the known universe, it still takes time for the radiation to travel across the vast distances of space Therefore, when we look at stars and other distant objects in space, we are actually looking back in time. Light travels at a speed of 300,000,000 mps or 9.5 trillion km per year.

12. Light-Years The distances in space are vast. Scientists use the distance that light travels in 1 year to measure distances in space. A light-year is the distance that light travels in 1 year, which is 9.5 trillion km. When we observe the light emitted from objects trillions of miles away, we are observing light emitted in the past. It takes about 8 minutes for light from the Sun to reach Earth

13. Light years The closest star to Earth other than the Sun is called Proxima Centauri, which is located about 4.2 light-years from Earth. Light emitted by Proxima Centauri takes 4.2 years to reach Earth. When we observe light from Proxima Centauri, we are observing how it appeared 4.2 years ago. This means scientists can observe light from across the universe that was emitted millions or even billions of years ago. They could even look at a star that no longer exists!

14. Spectroscopy-the study of the EMS to determine an object’s composition We can understand the composition of objects such as stars by analyzing the light these objects emit or reflect. Scientists have determined the colors given off by different elements when they are burned. By studying the colors given off by a star, we can discover the elements that make up a star.

15. The Doppler Effect If an object emitting electromagnetic or sound waves is moving toward you, the waves become compressed and shorter. If an object emitting electromagnetic or sound waves is moving away from you, the waves become stretched and longer. Blueshift-When a star is moving toward Earth, the light waves emitted by the star become compressed. The shorter wavelengths cause the star's light to appear blue. Redshift-When a star is moving away from Earth, the light waves emitted by the star become stretched. The longer wavelengths cause the star's light to appear red.

16. Doppler Effect A scientist named Edwin Hubble used visible light to provide evidence that the universe is expanding through his observations of the Doppler effect. All the galaxies we can observe experience redshift. Therefore, they must be moving away from Earth. If all of the objects in the universe are moving away from each other, the universe must be expanding. The universe is expanding at an increasing rate.

17. Using EMS other than visible light Objects and events in the universe give off high-frequency radiation such as ultraviolet radiation, X-rays, and gamma rays. Scientists can also use the low-frequency parts of the electromagnetic spectrum, such as radio waves, microwaves, and inrfared radiation to study the universe. Scientists can use special instruments, called remote sensing instruments, to detect this radiation and study the objects emitting it

18. Cosmic Background Microwave Radiation Scientists discovered that there are microwaves coming from every direction in space This is called the cosmic microwave background radiation, or CMBR for short. The CMBR comes from radiation created at the beginning of the universe. Used as evidence to support Big Bang Theory

19. Using EMS other than light-x-ray images- neutron stars and black holes

20. Gamma Rays Supernova explosions

21. Fundamental Questions- What units are used to measure distances in space? Light years What is meant by the speed of light? What is a light year? A light year is the distance that light travels in 1 year, which is 9.5 Trillion km How long does it take for light from the Sun to reach Earth. 8.3 minutes

22. Fundamental Questions Describe the electromagnetic spectrum and the wavelengths from long to short. Radio, microwave, infrared, visible light, ultraviolet, xrays, gamma rays Why are images seen through a telescope considered to be information from the past? Light travels 300,000 mps. It takes time for light to travel vast distances, therefore when we observe light from stars, we are observing light emitted in the past,

23. Fundamental Questions What are blueshift and redshift, and what do they tell us about an object’s movement in space? Blueshift-When a star is moving toward Earth, the light waves emitted by the star become compressed. The shorter wavelengths cause the star's light to appear blue. Redshift-When a star is moving away from Earth, the light waves emitted by the star become stretched. The longer wavelengths cause the star's light to appear red. What is frequency? The amount of waves of light that pass a point in 1 second Which wavelengths have the highest frequency and energy? The shortest wavelengths, such as ultraviolet, xrays, and gamma rays have the highest energy and frequency What color is visible light, and what colors is light comprised of from longest to shortest wavelength? Visible light is white, and is comprised of red, orange, yellow, green, blue, indigo, violet.