1. Using Technology to Interpret Space

3. Triangulation
Used to help measure distant objects indirectly or in space!
Based on the principals of triangle geometry
We need 3 pieces of information to solve for “D”:
A baseline (S)
The two angles between the baseline and target object (A and B)

4. Measure a baseline
Select an object to be the top point of the triangle
At one end of the baseline use a protractor to measure the angle between it and the top of the triangle
Repeat at the other end of the baseline for the other angle
Make a SCALE drawing using the baseline and the angles
Mark a perpendicular line on your scale drawing. Measure the line and use the scale to convert it to the actual length

5. Example 1 2. Use a protractor to determine the angles of the triangle
1. Measure your baseline
2. Use a protractor to determine the angles of the triangle
3. Make a scale diagram
55o
45o
 m 

6. Example 1
Scale of drawing: 1 m = 1 cm
4. On your scale drawing, make a perpendicular line from the baseline to the object
5. Measure this line
6. Use the scale to convert it to the actual length
5.5 cm
55o
45o
 cm 
Big . = Big m = x = m
Little Little cm cm

7. When do we use triangulation???
Parallax is the apparent shift in position of a nearby object when the object is viewed from two different places.
Thumb example – Hold out your arm and stick out your thumb
With your right eye closed, look at an object on the far wall behind your thumb. Now, look with your left eye closed Has the background moved????

8. Parallax
Astronomers use a star’s parallax to determine what angles to use when they triangulate the star’s distance from the Earth.
The larger the baseline, the more accurate the result.
The longest baseline that astronomers can use is the diameter of Earth’s orbit.
Measurements have to be taken six months apart to achieve the diameter of the orbit.

9. Composition of Stars
Isaac Newton passed a beam of light through a prism to produce a spectrum of colors.
Joseph von Fraunhofer used a spectroscope to observe the spectrum produced by the Sun. He noticed dark lines, called spectral lines. At the time he was unaware of what these lines were.
The significance of the spectral lines was discovered about 50 years later when Kirschoff and Bunsen, two chemists, used a spectroscope to observe various chemicals when they were heated.
H-R animation
Star Spectra (Gizmo)

10. Spectroscopy for Astronomers
Astronomers refract the light from distant stars to determine what the star is made of.
Stars have dark bands in distinct sequences and thicknesses on their spectra.
Each element that is present in the star creates its own black-line ‘fingerprint’
Spectral Composition
Video part 1
Video part 2
Video part 3

11. Doppler Effect
A change in the pitch of sound waves is because they are stretched or squeezed. This is known as the Doppler effect.

12. Like sound, light also travels in waves. Therefore:
If an light emitting object is moving towards you, it’s light waves are compressed (shift towards the blue side of the visible spectrum)
This is known as blue-shift
If a light emitting object is moving away from you, it’s light waves spread out (shifts towards the red side of the visible spectrum)
This is known as red shift

13. Red Shift-Blue Shift
The amount of shift indicates the speed at which the star is approaching or moving away.

14. Analyzing the blue-shift and red-shift in the spectra of stars and galaxies shows astronomers whether the bodies are moving toward Earth (A) or away from Earth (C).
No shift in the spectrum (B) means that the star and Earth are moving in the same direction. The star is said to be stationary A B C

15. Technology for our use:
One of the most common applications of the Doppler Effect today is the radar gun used by police.
The radio signal is sent out from the gun at a known wavelength; a moving car generates a returning wavelength.
The size of the difference in the two wavelengths shows how fast the vehicle is moving
Doppler Effect Learning Gizmo

16. Homework
Page 454 #1-7
Section 3 Review Page 455 # 1-3, 5-7