On Target? Do this on your Warm Up worksheet! No warm up today-get out your lab notebook and turn to your review table!

For today... 1.Warmup 2.Review

ANNOUNCEMENTS! Test on Thursday! Checking grades: I will be sending s home to parents after the test on Thursday if you are failing my class! Study hard! Keep up with your lab notebooks! I will be in the library after school TODAY if you need help understanding or studying! Remember-I don’t take late work. Make sure you’re turning everything in ON TIME! Honors: self-assessment assignment is due ON THURSDAY!

Fill this out in you lab notebook with your group: ActivityProperties (Big Ideas!) Significance to Astronomy Stellar Parallax and finger model Slinky Lab EM Waves in Space and Cell Phones Watt’s Up? Starburst Graphing and Inverse Square Law Star Spectra and Intensity Graphs

REVIEW ANALYSIS 1.The Sun is a yellow-white star. What range of surface temperatures would you expect on the Sun? 2.Spectral analysis of a star reveals that its light has a peak intensity at a wavelength of 640nm. Sketch a graph of the spectrum from this star and describe it’s temperature and color.

ANALYSIS: On the back 1.Spectral analysis of a star reveals that its light has a peak intensity at a wavelength of 640nm. Sketch a graph of the spectrum from this star and describe it’s temperature and color.

REVIEW ANALYSIS A star has a peak intensity at 640 nm. What color is it? What temperature is it? Formula: T (K) = 2.9 X 10 6 Peak wavelength

REVIEW ANALYSIS Explain to your neighbor what is happening in this picture! Why does the yellow star appear to change positions? Why does the yellow star appear to move more than the other stars in the photo?

I have two stars. Star A is 4.36 light-years (ly) from Earth, while Star B is 4.22 ly from Earth. When viewed from Earth in June, and again, in December, which star appears to shift the greatest distance compared to very distant background stars? EXPLAIN WHY. (1 light year = 9.5 trillion kilometers!) REVIEW ANALYSIS

Parts of a Wave-Draw and label wavelength, frequency, and amplitude Objective: I can describe the parts of a wave and label these parts on a drawing of a wave

Frequency of a Wave

What did we find? Changing the wavelength, frequency, and amplitude does not change the speed of the wave Changing the medium that the wave travels through does. Only the material through which the wave travels (the medium) affects the speed of a wave-changing the tension of the slinky! Objective: I can test what variables change the speed of a wave and summarize class data for how wave speed changes.

You and your best friend are having a race from the Sun to the Earth. You are riding a red wave. Your bff is riding a blue wave. Who will win the race? Explain why!  “I think that… because…”

Speed of a Wave WHAT WE KNOW:  Speed = distance/time But what if we don’t have a fast enough stop watch?  Speed = wavelength * frequency c = λ * ν

Why do we see COLOR?

Read: EM Waves in Space- Rainbows From Outer Space (p. 481 – 484) Answer the Following Questions in your Lab Notebook: What type of wave travels through space, carries energy, and is a type of radiation? Visible light is an example of _______________ waves, also called EM ________. The speed of light is ________ at _________m/s. What is the equation that relates speed, wavelength and frequency? At a constant speed, when the _________ of a wave increases, the wavelength __________. All waves in the EM spectrum vary in ____________ and __________ but have the same ___________, the _______ of ________.

How do cellphones work? Voice Electrical signal (microphone) EM wave (antenna) Frequency adjustment and matching with tower Other phone antenna Converted to electrical Converted to voice

Why are some stars brighter than other stars?

Why do some stars look brighter than others? Why is the sun the brightest star we can see? It’s closest to us Is the sun the brightest star in the universe? NO! Polaris (the north star) is 2200 times brighter Does that mean stars closer to us are always brighter? NO! Polaris (the north star) is 433ly away but Proxima Centauri is 4.2ly away. We can’t even see Proxima Centauri without a telescope because it’s so dim. I can explain why some stars look brighter than others.

When you look at the bulb, energy enters your eyes. When you place your hand near the bulb, energy hits your hand. Do your eyes or your hand receive all of the energy produced by the bulb? I can explain why some stars look brighter than others.

Why does Stellar Parallax not work for all stars? Some stars are too far away (shift is so small, it is not noticeable or there aren’t enough background stars for good comparison Apparent Brightness and Luminosity are used for these stars.

Inverse Square for light What is the change in apparent brightness of a star if you move twice the distance?

Answer In Your Lab Notebook! If the distance from the source of energy increases 4 times, what happens to the apparent brightness, provided the luminosity remains the same? *Remember your inverse square law equation! d=distance to the star, b=the apparent brightness of the star L=the luminosity of the star.

How do we know luminosity? Several different ways... Read pg 498 and answer these questions in your lab notebook: To find the distance to a star using the inverse square law, what 2 things do you need to know? How would scientists use the inverse square law to find the luminosity of a nearby star? If the distance to star A is 10 times greater than the distance to star B, and the two stars have the same luminosity, how would their apparent brightness compare?