Download Topic 3

Key Terms
Use the spaces below to define the key terms in your own words.
3.1
Key Terms
Textbook Definition
Drawing / In my own words
Textbook Definition
Drawing / In my own words
Textbook Definition
Drawing / In my own words
Refracting
Telescope
Reflecting
Telescope
Interferometry
Hubble Space
Telescope
3.2
Key Terms
Electromagnetic
Energy
Electromagnetic
Spectrum
Radio Telescopes
Space Probes
3.3
Key Terms
Triangulation
Parallax
Doppler Effect
(Doppler Shift)
Spectrometer
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CHAPTER 3 – OPTICAL TELESCOPES, RADIO TELESCOPES, AND OTHER TECHNOLOGY ADVANCES OUR
UNDERSTANDING OF SPACE
3.1 – USING TECHNOLOGY TO SEE THE VISIBLE
Optical Telescopes
Lenses or mirrors gather and focus __________; the _______________ the lens or mirror, the greater
the light-gathering capability of the telescope.
_________________ telescopes have been used for 400 years beginning with Dutch lens-grinding
technology and Galileo’s first telescope observations in the 1600s.


__________________ telescope
o uses two _______________ to gather and focus light
o disadvantage: the maximum lens size is about 1 m
_________________ telescope
o uses curved ___________________ to gather and
focus light
o advantage: can be segmented instead of being one
single piece and can reach a size of 10 m
o e.g. Keck telescopes on Mauna Kea, Hawaii
Interferometry
Telescopes can be _______________ together for greater
magnification and resolution. The combined telescopes are spaced
separately but have their images combined digitally using
__________________.


_____________________ = making an object appear larger
___________________ = the ability to distinguish two points
as different
The Hubble Space Telescope
The Hubble telescope is a _______________________ telescope orbiting ___________ at an altitude of
600 km. It is currently the best “Earth-based” method of reducing ___________________________ from
moisture, clouds, wind, air and light pollution.
The Hubble Space Telescope is a cooperative program of the European Space Agency (ESA) and NASA to
operate a long-lived space-based ______________________ for the benefit of the international
astronomical community.
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HST was envisioned in the ‘40s, designed and built in the ‘70s and ‘80s, and operational in the ‘90s. HST
was designed to be a long term space-based observatory. To accomplish this and protect the spacecraft
from instrument and equipment failure, regular ________________________ missions occur.
Hubble has special grapple fixtures, 76 handholds, and is stabilized in all three axes. HST is a 2.4-meter
reflecting telescope and was deployed by the space shuttle Discovery in 1990.
(http://www.youtube.com/watch?v=jw8VYKGQk-I and http://www.youtube.com/watch?v=--X9zfgZtS0)
Assignment – Pg. 439
1. Why is there a need for telescopes?
2. What type of optical telescope uses mirror to focus light?
3. Describe the advantage of using a segmented mirror telescope.
4. Describe the technique called interferometry.
5. The resolving power of a telescope is a measure of its:
a.
b.
c.
d.
Operating ability under poor weather conditions
Magnification
Ability to distinguish details in an object
Quality in general
6. Large ground-based telescopes are built with the ability to move to oppose the movement of Earth.
Why is this necessary?
7. Describe two advantages of reflecting telescopes over refracting telescopes.
8. Why is the Hubble Space Telescope a reflector and not a refractor?
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9. Even though it has a smaller mirror than many Earth-based telescopes, the Hubble Space Telescope
can see objects more than 50 times farther than what Earth telescopes can see. Explain why that is.
10. a) What happens to the detection capabilities of two reflecting telescopes working together?
b) Would two refracting telescopes have the same capabilities? Explain your answer.
3.2 – USING TECHNOLOGY TO SEE BEYOND THE VISIBLE
Current technology does not rely on the visible __________________ of light alone to explore the
universe. Many objects also radiate invisible forms of ______________________ energy at the speed of
light.



Examples are X-rays, radio waves, microwaves, infrared, ultraviolet and gamma rays. Each type
of wave has a distinctive ______________________ and __________________.
wavelength - the _____________________ from one point of a wave to the next point (e.g.
crest to crest)
frequency - ________________ of waves passing a point per second
What are the advantages in using other parts of the electromagnetic spectrum to study the sky instead
of relying on light?
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1)
2)
3)
4)
5)
6)
Radio waves can ___________ easily through most surfaces
Not effected by ________________________
Detected _______ or _____________
Not _______________ by clouds or atmosphere and pollution
Can travel farther then light
______________________ form of energy to humans.
Combining the power of the Hubble Space Telescope with the Chandra X-ray Observatory, researchers
have made images of a rotating star that provides new clues about how the
powerful object works.
Radio Telescopes
Radio telescopes are basically ___________________ dishes made of metal
mesh. The dish is a large _____________________ that gathers and focuses
radio waves onto the middle receiver where they are converted to electrical
impulses then sorted out by a ___________________________.
http://www.youtube.com/watch?v=brDCI5UHjUE
_________________________, or using arrays, can be used to simulate a much
larger telescope. Ex. Two small radio telescopes 100m apart mimic the ability of one single
radio telescope with a dish diameter of 100m!
Black holes are objects with such high _________________ that not even light can escape.
They may be formed when the most massive of stars die and their cores collapse into a
super-dense mass.
Space Probes
Optical and radio telescopes can find out much about the ____________________ of
matter in the universe. But one thing they cannot do is conduct tests on __________, for example, on
Mars.
Accurate knowledge about the soil is needed in planning the first _______________ mission to Mars.
Space probes and robot explorers, though extremely _____________________, provide this information
without ________ to human life.
Assignment – Pg. 445
1. What is electromagnetic radiation?
2. Name four other forms of electromagnetic radiation besides visible light.
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3. How is wave frequency related to wavelength?
4. What advantages are there to using space probes rather than manned flights?
5. What are the sources of radio waves from space?
6. Why aren’t television signals visible to us?
7. Explain two advantages of using radio telescopes instead of optical telescopes.
8. a) Explain how all forms of electromagnetic radiation are similar to each other.
b) Explain how each form is different from the others.
9. When combining information from multiple telescopes, the length of the distance between the
telescopes is very important. Is there a limit to how far that distance can be: a) on Earth? B) in
space?
3.3 – USING TECHNOLOGY TO INTERPRET SPACE
What Are Stars Made Of?
Astronomers use the visible ________________ of light to study the composition of stars from here on
Earth. Each star emits a ____________________________ of black lines where its elements absorb light.
The resulting spectrum looks like a rainbow with black vertical lines on it.
The instrument used to analyze a star’s
spectrum is called a
______________________. The other data
needed is a list of known spectra for
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__________________ in the Periodic Table.
Star Direction of Motion
Scientists can determine if a star is moving __________________ or
_______________ from us by looking for a blue-shift or red-shift in the
light that reaches Earth.
The principle involved is the _________________ effect.
(http://www.youtube.com/watch?v=Tn35SB1_NYI and
http://www.youtube.com/watch?v=4cCk1MXJHm0)
The pitch (tone) of a sound wave _______________ depending on whether the
object is moving toward or away from the observer.
Light is also made of ________________, so light can also change depending on
whether it is moving toward or away from the __________________.
For example: an ambulance siren’s pitch is ____________________ as it
approaches the observer and falls as it passes by. This is because the
_______________ in front are compressed and in back are stretched out.
Compressed waves are pitch, stretched waves are low pitch.
A star moving toward Earth will have its waves
__________________ (short light waves are blue). This
is called a ____________ shift. A star moving away will
have its waves __________________ (long light waves
are red). This is called a ________ shift.
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Measuring Distance
Mathematics and physics are powerful tools in helping to measure distances in space. Two methods for
calculating ______________________ include:


______________________
___________________
Triangulation is based on ___________________ while parallax uses the apparent __________ of an
object compared to its background when viewed from two different angles.
Parallax
Parallax is the apparent ___________ of a nearby
object compared to more distant
_________________ objects. It occurs when the
target object is viewed from two different
_______________. These two different views are
then used in triangulation calculations. The largest
___________________ on Earth is the diameter of
Earth’s orbit around the Sun.
*** 1 AU = 150,000,000 km
***
How long apart would measurements be taken?
Triangulation
1. Locate the object whose distance is to be measured.
2. Measure a baseline. The longer, the better.
3. From the ends of the baseline, measure the angles “a” and “b” to
the target object.
4. Draw a scale diagram.
5. Draw a perpendicular line.
6. Measure the perpendicular line.
7. Convert to real distance.
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Assignment – Pg. 454
1. Explain the meaning of triangulation and give an example of a situation in which it might be used.
2. How is parallax used to measure distances in space.
3. a) What is a spectrum?
b) What can a star’s spectrum indicate about a star?
4. What is the Doppler Effect? Give an example of its use.
5. When using the triangulation technique, why is it important to measure the baseline correctly?
6. How do astronomers determine the elements that make up a star?
7. Explain why the spectra of some stars shift.
8. What type of shift in the spectrum would you expect from a star that was:
a. Moving in the same direction as Earth, at the same speed as Earth?
b. Moving at right angles to the direction of sight?
9. What conditions would have to be met in order for an ambulance with its siren on not to exhibit the
Doppler Effect when it passes you?
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Section Review – Pg. 455
1. With the aid of two diagrams, describe how refracting and reflecting telescopes work.
2. Explain why infrared telescopes would not be useful for stargazing in a city.
3. What is the advantage of using telescopes set up in an array?
4. What is a spectrometer used for?
5. If you see a red-shifted star, what does that tell you about the direction in which the star is moving
through space? Explain your answer.
6. You are the owner of a company that wants to build the largest optical telescope in the world.
Which type would you choose and why?
7. Why can radio astronomers make observations at any time during the day, but optical astronomers
are mostly limited to making their observations at night?
8. Why do different elements in a star display different patterns of lines in their spectra?
9. Why is the Doppler Effect important to astronomers?
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