Thursday, November 29, 2012

Shifting through space - Doppler effect - red or blue shift

after our introduction of wave, we will explore the concept of how wave travel through space.
which will also help find some evidence to support the Big Bang theory. watch video...
remember the lab#3 on spectroscopy --- http://coolcosmos.ipac.caltech.edu/cosmic_games/spectra/index.html

Let's say you are sending a spacecraft to Mars. You'd like your spacecraft to help you figure out what the rocks on Mars are made of. Or, let's say you'd like to know what gases are in the planet Jupiter's atmosphere. Or, maybe a strange gas has entered your school building and you'd like to figure out if it's dangerous or not. A spectrometer will help you in all these cases. It turns out that different substances absorb or emit light at different wavelengths in the Electro Magnetic (EM) Spectrum. If you shine the light you get from burning sodium into a prism or diffraction grating or other spectrometer, you'll find that the light comes out in bands of color at different places on the spectrum.
The amazing thing is, every time you see burning sodium, you'll see this same pattern of light if you send it through a spectrometer. You will always see those same bright aqua and green lines by themselves in the middle of the spectrum. These lines are called spectral lines, and they are related to the way the atoms in the material are arranged.

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Variations in Air Pressure and Corresponding Waveform
Loudspeaker and Waveform

watch a video on The Doppler Effect

Suppose that there is a happy bug in the center of a circular water puddle. The bug is periodically shaking its legs in order to produce disturbances that travel through the water. If these disturbances originate at a point, then they would travel outward from that point in all directions. Since each disturbance is traveling in the same medium, they would all travel in every direction at the same speed. The pattern produced by the bug's shaking would be a series of concentric circles as shown in the diagram at the right. These circles would reach the edges of the water puddle at the same frequency. An observer at point A (the left edge of the puddle) would observe the disturbances to strike the puddle's edge at the same frequency that would be observed by an observer at point B (at the right edge of the puddle). In fact, the frequency at which disturbances reach the edge of the puddle would be the same as the frequency at which the bug produces the disturbances. If the bug produces disturbances at a frequency of 2 per second, then each observer would observe them approaching at a frequency of 2 per second.
Now suppose that our bug is moving to the right across the puddle of water and producing disturbances at the same frequency of 2 disturbances per second. Since the bug is moving towards the right, each consecutive disturbance originates from a position that is closer to observer B and farther from observer A. Subsequently, each consecutive disturbance has a shorter distance to travel before reaching observer B and thus takes less time to reach observer B. Thus, observer B observes that the frequency of arrival of the disturbances is higher than the frequency at which disturbances are produced. On the other hand, each consecutive disturbance has a further distance to travel before reaching observer A. For this reason, observer A observes a frequency of arrival that is less than the frequency at which the disturbances are produced. The net effect of the motion of the bug (the source of waves) is that the observer towards whom the bug is moving observes a frequency that is higher than 2 disturbances/second; and the observer away from whom the bug is moving observes a frequency that is less than 2 disturbances/second. This effect is known as the Doppler effect.
The Doppler effect is observed whenever the source of waves is moving with respect to an observer. The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding. It is important to note that the effect does not result because of an actual change in the frequency of the source. Using the example above, the bug is still producing disturbances at a rate of 2 disturbances per second; it just appears to the observer whom the bug is approaching that the disturbances are being produced at a frequency greater than 2 disturbances/second. The effect is only observed because the distance between observer B and the bug is decreasing and the distance between observer A and the bug is increasing.
The Doppler effect can be observed for any type of wave - water wave, sound wave, light wave, etc. We are most familiar with the Doppler effect because of our experiences with sound waves. Perhaps you recall an instance in which a police car or emergency vehicle was traveling towards you on the highway. As the car approached with its siren blasting, the pitch of the siren sound (a measure of the siren's frequency) was high; and then suddenly after the car passed by, the pitch of the siren sound was low. That was the Doppler effect - an apparent shift in frequency for a sound wave produced by a moving source.

The Doppler effect is of intense interest to astronomers who use the information about the shift in frequency of electromagnetic waves produced by moving stars in our galaxy and beyond in order to derive information about those stars and galaxies. The belief that the universe is expanding is based in part upon observations of electromagnetic waves emitted by stars in distant galaxies. Furthermore, specific information about stars within galaxies can be determined by application of the Doppler effect. Galaxies are clusters of stars that typically rotate about some center of mass point. Electromagnetic radiation emitted by such stars in a distant galaxy would appear to be shifted downward in frequency (a red shift) if the star is rotating in its cluster in a direction that is away from the Earth. On the other hand, there is an upward shift in frequency (a blue shift) of such observed radiation if the star is rotating in a direction that is towards the Earth.
http://coolcosmos.ipac.caltech.edu/cosmic_classroom/cosmic_reference/redshift.html

Redshift

Astronomers often use the term redshift when describing how far away a distant object is. To understand what a redshift is, think of how the sound of a siren changes as it moves toward and then away from you. As the sound waves from the siren move toward you, they are compressed into higher frequency sound waves. As the siren moves away from you, its sound waves are stretched into lower frequencies. This shifting of frequencies is called the Doppler effect.
A similar thing happens to light waves. When an object in space moves toward us it light waves are compressed into higher frequencies or shorter wavelengths, and we say that the light is blueshifted. When an object moves away from us, its light waves are stretched into lower frequencies or longer wavelengths, and we say that the light is redshifted.
In the visible portion of the electromagnetic spectrum, blue light has the highest frequency and red light has the lowest. The term blueshift is used when visible light is shifted toward higher frequencies or toward the blue end of the spectrum, and the term redshift is used when light is shifted toward lower frequencies or toward the red end of the spectrum. Today, we can observe light in many other parts of the electromagnetic spectrum such as radio, infrared, ultraviolet, X-rays and gamma rays. However, the terms redshift and blueshift are still used to describe a Doppler shift in any part of the spectrum. For example, if radio waves are shifted into the ultraviolet part of the spectrum, we still say that the light is redshifted - shifted toward lower frequencies.
The light from most objects in the Universe is redshifted as seen from the Earth. Only a few objects, mainly local objects like planets and some nearby stars, are blueshifted. This is because our Universe is expanding. The redshift of an object can be measured by examining the absorption or emission lines in its spectrum. These sets of lines are unique for each atomic element and always have the same spacing. When an object in space moves toward or away from us, the absorption or emission lines will be found at different wavelengths than where they would be if the object was not moving (relative to us).
The change in wavelength of these lines is used to calculate the objects redshift. Redshift is defined as the change in the wavelength of the light divided by the wavelength that the light would have if its source was not moving (called the rest wavelength).
Redshift = (Observed wavelength - Rest wavelength)/(Rest wavelength)
Cosmological Redshift

The cosmological redshift is a redshift caused by the expansion of space. As a result of the Big Bang (the tremendous explosion which marked the beginning of our Universe), the Universe is expanding and most of the galaxies within it are moving away from each other. Astronomers have discovered that all distant galaxies are moving away from us and that the farther away they are, the faster they are moving. This recession of galaxies away from us causes the light from these galaxies to be redshifted. As a result of this, at very large redshifts, much of the ultraviolet and visible light from distant sources is shifted into the infrared part of the spectrum. This means that infrared studies can give us much information about the ultraviolet and visible spectra of very young, distant galaxies.

Doppler Shift Interactive (70.0K)
Astronomers use the Doppler Effect to determine the motion and speed of galaxies and other distant objects. This Interactive shows you what the Doppler Effect is: how the frequency and wavelength of light or sound waves change as the source or the observer (or both) move relative to each other. Click on the buttons to make the Observer, the Source or Both approach, and observe the waves on the graph. Or take matters into your own hands by clicking and dragging on the spaceship to change its velocity.

Sunday, November 25, 2012

star's life cycle




History Channel documentary on star's life cycle but its much longer... http://www.youtube.com/user/kmehtas

Stars Life And Death of a Star part 1 of 5

Formation of a whopper 100 solar mass star

 


another version http://www.calpoly.edu/~rechols/astropicslab7/hrevolutionary.jpg
Extra credit: watch and do a report on this video>>> click here
watch LIGHT SPEED


and for the Galaxy: see http://www.youtube.com/user/Spyrox08
part 1 part 2  Part 3 (sorry discovery block part 1 and 3) T-T...
see if you can find it from Discovery Channel
 http://dsc.discovery.com/tv-shows/other-shows/videos/how-the-universe-works-the-shape-of-galaxies.htm

Thursday, November 15, 2012

Lab #5: Solar system in Scale

Solar system and Planets in Scale:

click to see instruction: front page, back page...




also on Nov 16 , Friday you can observe the Leonid Meteor Shower Webcast  at NASA!
Leonid Meteor Shower 2012 Sky Map
This sky map for the Leonid meteor shower of 2012 shows the location of the radiant (center) before dawn on Saturday, Nov. 17 - the peak viewing time.
CREDIT: StarDate.org

                                                            


The annual Leonid meteor shower will peak overnight tonight (Nov. 16) and early Saturday (Nov. 17), and you can watch the celestial fireworks show live via a NASA webcast.
Scientists at NASA's Marshall Space Flight Center in Huntsville, Ala., will provide a live views of the Leonid meteor shower from an all-sky camera beginning late Friday afternoon and running through early Saturday morning.
The webcast will be embedded below when it begins by 7 p.m. EST (0000 Nov. 17 GMT):

If you can't see the screen above, you can also directly access the Marshall Leonids Ustream feed at this link: http://www.ustream.tv/channel/nasa-msfc 

Wednesday, November 14, 2012

Review for Test #3 (11-21-12) Study the notes and the LABs

ESRT Pg 14
http://www.youtube.com/embed/videoseries?list=PL09E558656CA5DF76 
* Tour of the EMS 01 - Introduction by ScienceAtNASA 37,423 views 3:04
Tour of the EMS 02 - Radio Waves by ScienceAtNASA 18,484 views 3:39
Tour of the EMS 03 - Microwaves by ScienceAtNASA 13,763 views 5:23
Tour of the EMS 04 - Infrared Waves by ScienceAtNASA 14,393 views
* Tour of the EMS 05 - Visible Light Waves by ScienceAtNASA 19,477 views 3:40
Tour of the EMS 06 - Ultraviolet Waves by ScienceAtNASA 14,676 views 5:03
Tour of the EMS 07 - X-Rays by ScienceAtNASA 14,476 views 2:50
Tour of the EMS 08 - Gamma Waves by ScienceAtNASA 13,658 views 3:42 http://www.youtube.com/embed/videoseries?list=PL09E558656CA5DF76 leave me a note... so I know you watched them all... Test on Wednesday! Happy Thanksgiving!

Astronomy Review: 

watch this video.... Intro+to+the+Universe+movie

Lab# 3 Spectrum of the Stars click to watch the video
Lab #4 HR diagram on ESRT pg 15

Describe the different types of star.
MAIN SEQUENCE: Most stars are like this.
GIANT STAR: Cool large star
RED SUPERGIANT: Very large, very cool, very rare
WHITE DWARF: Small, very hot star

and being able to interpret the HR diagram fully! 
and Lab #5 distance and scale planets of the solar system....
ASTRONOMICAL UNIT: The average distance between the Earth and the Sun (1AU = 1.5 x 1011m
Define the light year.
LIGHT YEAR: The distance that light travels in one year. 1 ly = 9.46 x 1015 m
(1 ly = 63 000 AU)
Compare the relative distances between stars within a galaxy and between galaxies, in terms of order of magnitude.
GALAXY: A group of stars held together by gravity. Typically contains 1011 stars and is 105 ly across. Distances between stars approx. 100 ly. Distance between galaxies 106 ly. Shapes can be spiral, globular or irregular

 

Tuesday, November 13, 2012

Solar Eclipse 2012 - Cairns AU with HW#5B


looking for Home work 5B: topic 3 Review Q&A ?
after reading pg 48, 49, 50 click to see the original size
goto topic3 Question 30-43 Question 44 to50
if you don't want to write the Question print them out!
 

Friday, November 9, 2012

Wavelength data worksheet notes

first of all say happy birthday to CARL SAGAN

According to the handout given in class...see http://science.hq.nasa.gov/kids/imager/ems/ 
http://missionscience.nasa.gov/ems/09_visiblelight.html

but this one  seems better....
http://www.physicsclassroom.com/class/waves/u10l2a.cfm

Check Your Understanding

Consider the diagram below in order to answer questions #1-2.
1. The wavelength of the wave in the diagram above is given by letter ______.

2. The amplitude of the wave in the diagram above is given by letter _____.

3. Indicate the interval that represents one full wavelength.
a. A to C
b. B to D
c. A to G
d. C to G



Wavelength of Light


Ever wonder how we able to see the color and how we interpret them. The reason for the interpretation is that the colors are nothing but the electromagnetic radiations with different wavelengths. The visible region of the electromagnetic spectrum is also known as Visible Light. In the below section we will discuss light and the characteristics of different wavelengths of the visible spectrum. Before we proceed forward let us understand the concept of light.

It is an electromagnetic wave which is visible to human eyes. It extends from the infrared region in EM spectrum to the UV region. Other than these regions humans are unable to see. Although we won’t be able to see the region other than the visible region still the infrared and ultraviolet region both are useful for us.
The colour of the object which we see is due to the fact that the object emits that color and it absorbs all the other colours.

Wavelength of Visible Light

Back to Top
As already discussed, the Wavelength of Visible Light ranges from 400 – 700 nm. In this section let us discuss wavelength of different colours of the visible light spectrum.

Spectrum

The visible spectrum of the electromagnetic spectrum is known as visible light. The visible spectrum has various different color with different wavelengths. The violet color has shortest wavelength while the red color has the longest wavelength. It can be seen in the above diagram.

The Wavelength spectrum is explained by the spectrum of electromagnetic spectrum. The electromagnetic spectrum extends from low frequencies to almost infinite frequencies. The low frequencies results in very large wavelength as we know that the wavelength and frequency are inversely proportional to each other and the infinite frequency corresponds to almost zero wavelength which is measured in Plank's length. The Wavelength spectrum has the following range as shown in the figure:
Wavelength Spectrum

Frequency to Wavelength


Frequency and wavelength are the basic concepts in waves.
In Electromagnetic waves the frequency and wavelength plays a very significant role. There are different types of waves with varying frequency and wavelength in this spectrum.
In order to know the which type of wave it is, we need to understand the Frequency Wavelength Relationship.



***************************** on other notes....lol which one are you? 

Tuesday, November 6, 2012

Lab#4: Some important characteristics of stars

listen to a college professor's lecture about....
Some Important Characteristics of Stars
Last: ______________________ First: ________________ Period: ____ Group: _____ Date:      /       /
Group Members: ________________________, ________________________, ________________________
Read, Understand and Apply!
Failure is not an option!
Investigative Question: How do scientists classify stars?
Materials:  ESRT, color pencils (red, orange, yellow, white, light blue, blue), circle template, stencils or different size/color stickers
Introduction: Astronomers use two basic properties of stars to classify them. These two properties are luminosity and surface temperature. Luminosity refers to the brightness of the star relative to the brightness of our sun if they were located next each other. In order to calculate this value, scientists must know the size (surface area), distance and real temperature of the star.

L=4Ï€r2f
L=Luminosity r=radius f=energy flux of the surface of the star (S x T4) S=Stefan-Boltzmann Constant
*Flux is the amount of light that comes from a certain area in a certain amount of time.

A bigger star will appear brighter than a smaller star of the same temperature when placed next to it. For example, 10 light bulbs of the same power (wattage) and temperature will appear brighter than a single light bulb because, cumulatively, they have a larger surface area.  Another example, a flash light and a searchlight have similar temperature, therefore similar flux, but from a distance of 100 meters, the search light is the brighter of the two. Why? Because, the search light is bigger and has a larger surface area than the flashlight.

A star has the same surface temperature as the sun, but its ten times larger in radius would be 100 times the luminosity of the sun. If the distance between earth and the sun increases 10 times the sun will appear 100 times dimmer.

Star A and B have the same radius. If star A has a temperature that is twice higher than star B then Star A will be 16 time more luminous than Star B.

Astronomer will often use a star’s color to measure its temperature.  Stars with low temperature produce a reddish light while stars with a high temperature shine with a brilliant blue-white light. Surface temperatures of stars range from about 3000 degrees Celsius to 50, 000 degrees Celsius. When these surface temperatures are plotted against luminosity, the stars fall into groups. Using data similar to what you will plot in this activity, Danish astronomer Ejnar Hertzsprung and US astronomer Henry Russel independently arrived at similar results in what is now commonly referred to as the HR diagram.
……………………………………………………… cut and paste into lab book ……..…………………………………......................  




Part 1: Pre-lab Exercise: Use your ESRT, Characteristics of Stars chart to answer the following questions   
1.      The horizontal axis represents _______________________ and _______________________
2.      The unit for temperature is ____, the range is from(smallest) _________ to _________ (largest)
3.      The vertical axis represents _______________________ and _______________________
4.      Scale range for Luminosity is from (smallest) _________ to _________ (largest)
5.       Each increment on Luminosity scale increases and decreases by __________ times.
6.      There are _____  major groups of stars labeled in this chart, which are: ________________________, ________________________, ________________________ and ________________________
7.      Complete the table below
Star
Temperature
Color
Luminosity
Size
Small, medium, massive
Barnard’s Star




Sun




Spica





……………………………………………………… cut and paste into lab book ……..…………………………………......................
Part 2: Characteristics of stars data table
Star
Surface
Temp. (K)
Luminosity
(x sun)
Circle size
Star
Surface Temp. (K)
Luminosity (x sun)
Circle size
Proxima Centauri
3042
0.0017
3/16”
Altair
6900
11
11/32”
40 Eridani B
3100
0.5
1/4”
Polaris
7200
2200
7/16”
Barnard’s Star
3134
0.004
3/16”
Procyon B
7740
0.001
3/16”
Betelgeuse
3140
120000
½”
Vega
9000
40
11/32”
Antares
3400
57500
½”
Sirius A
9940
25
11/32”
Lacaille
3626
0.03
7/32”
Rigel
12130
117490
½”
Aldebaran
3910
518
3/8”
Regulus
12460
288
3/8”
Ceti
4797
139
3/8”
Achemar
15000
3150
7/16”
Sun
5800
1
9/32”
Spica
22400
12100
½”
Procyon A
6530
7
5/16”
Sirius B
25200
0.03
7/32”

……………………………………………………… cut and paste into lab book ……..…………………………………......................  



Some Important Characteristics of Stars: STUDENT INSTRUCTIONS
Read, Understand and Apply!
Failure is not an option!
Procedure.  Record all observations in corresponding Data Tables, Charts and Graphs. Cut and glue the sections as you complete them. You must follow the sequence of instructions and procedure.
Cut and glue the introduction into your lab book. Read and understand the introduction.        
 Part 1. Pre-lab exercise: After reading the introduction, use your ESRT “Characteristics of Stars” chart and complete the blank spaces with appropriate terminology and values. Do not forget the correct units!  
Part 2.
a.      Use the surface temperature and luminosity values for Proxima Centauri and plot (with a dot) this data on the graph paper (Characteristics of Stars- HR Diagram) provided.
b.      Use the circle template/stencil and the size of the star provided in the data table and draw a circle around the dot, considering the dot is the center of the circle representing the star.
c.       Repeat the procedures a and b for all other stars, one at a time.
d.      Refer to ESRT “Characteristics of Stars” chart. Determine the colors and corresponding temperatures on the horizontal axis. Use this information and color each circle representing a star on the diagram you created. 

Part 3. Conclusion questions. Use diagram you created and the ESRT to answer the following questions. Use complete sentences and complete thoughts when answering.

1. What is the relationship between the size of stars and luminosity?

2. What is the relationship between the temperature and color exhibited by stars?

3. How do the luminosity and temperature of the Sun compare with those of other stars?

4. How is the Sun classified? Must state star group, temperature and luminosity.

5. How do astronomers estimate a star’s temperature?

6. Compared to Sun, the star Betelgeuse is: Must state size, temperature and luminosity.   

7. Name the star which is about 200 times brighter than the Sun but has a surface temperature about 2000 K cooler than the Sun.
8. The star with the lowest luminosity is the dimmest because of its surface temperature or size?
9. Use ESRT “Solar System Data” table to help you answer this question. If you were to observe the Sun from the Earth and Saturn at the same time, what would the Sun’s luminosity from Saturn be if the Sun’s luminosity from Earth is 1? Explain your answer.
10. Summarize how astronomers classify stars?


goto here for more notes to help you understand...

H-R Diagram (279.0K)
Manipulate the properties of a star (luminosity and temperature) and see how the star evolves along its evolutionary path at a rate determined by its nuclear burning timescale. As the star evolves, its color and size will change