Download What Channel is That?

DATE:
NAME:
Science 9
Space Exploration
CLASS:
What Channel is That?
Topic 5
Textbook
Read pages 393 – 397 in your textbook and answer the following questions
1. Define ELECTROMAGNETIC RADIATION -
2. In the space below, list all the waves that Electromagnetic Radiation (EMR) includes.
3. Astronomers use radio waves to learn about the composition of stars through a process known as
_______________________________.
Radio Telescopes
4. Telephone calls used to be made by ____________ waves. The reception was _________, and
people had to shout over hiss and ____________ on the line.
5. Karl Jansky was given the job of tracking down the radio emissions that were _______________
with these communications. He build a _______________________.
6. He learned to identify radio emissions that rose and set with the __________, __________, and
_________. He concluded that these radio waves sources came from ______________.
7. Grote Reber built a ________________ (radio telescope) and “listened” to the sky. “Listening” to
the stars would be like _____________ a radio between channels. The hiss would become
_____________ when he tuned in to an area in space that was giving off large amounts of radio
waves. These are known as _____________________.
Bigger Radio Telescopes
8. The resolving power of an optical telescope relates to the fineness of ___________ it can image.
The wavelength of the light is on factor for ______________ power. The smaller the wavelength,
the ___________ the resolving power.
9. Radio waves have wavelengths that are millions of times ______________ than light waves. This
means radio waves provide images with ___________ resolution that light waves. However,
radio waves penetrate ________________ in the galaxy where visible light stops.
“Seeing” Radio Waves
10. Radio telescopes ___________ “see” radio sources. In the early days, the movement of dials
and __________ monitored the incoming radio waves. Astronomers then ___________ the data.
11. Today, computers store the same data and false color it to produce ___________ of the radio
waves.
Optical Connections
13. Radio astronomers wanted to identify their ___________ radio sources with objects they had
seen with ______________ telescopes so they could be sure just what objects were emitting
radio waves. But radio images have (high/low) resolution.
Connecting Radio Waves
14. Astronomers improved radio images by connecting ________________. If two radio telescopes
are separated by some distance, but connected _____________________, their signals can be
combined using a computer.
15. The resulting images are as good as if one telescope were used that was as big as the
_____________ between the two. This method is called ______________________.
Radio Telescopes Bigger Than Earth
16. Define VERY LONG BASELINE INTERFEROMETRY –
17. VLBI produces images _______ times as detailed as the largest optical telescopes that exist
today. Astronomers combine signals from any (and as many) radio telescopes in the _________.
Astronomers record each telescope’s signal with _________________, which are then
transferred to computer disks, and combined to form _______ image.
Review:
18. How did Karl Jansky know that some radio waves come from space?
19. Why are radio telescopes built so much larger than optical telescopes?
20. Explain the technique of interferometry.
21. How is very long baseline interferometry different from normal interferometry?
22. If you were to build a radio telescope, would you build it in a country with lots or rain or
sunshine? Why?