Transcript GO 3_3 Interpreting Space

Using Technology to Interpret Space
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)
1. Measure a baseline
2. Select an object to be the top point of the triangle
3. At one end of the baseline use a protractor to measure
the angle between it and the top of the triangle
4. Repeat at the other end of the baseline for the other
angle
5. Make a SCALE drawing using the baseline and the
angles
6. Mark a perpendicular line on your scale drawing.
Measure the line and use the scale to convert it to the
actual length
Example 1
1. Measure your baseline
2. Use a protractor to
determine the angles
the triangle
3. Make a scale
diagram
of
45o
55o
---------10 m -------
Example 1
Scale of drawing: 1 m = 1 cm
5. Measure this line
45o
5.5 cm
4. On your scale drawing, make
a perpendicular line from the
baseline to the object
55o
6. Use the scale to convert
it to the actual length
------- 10 cm ------
Big . = Big
Little
Little
10 m =
x .
10 cm
5.5 cm
= 5.5 m
 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????
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.
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)
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
Doppler Effect
 A change in the pitch of sound waves is because
they are stretched or squeezed. This is known as
the Doppler effect.
 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
Red Shift-Blue Shift
 The amount of shift indicates the speed at which the
star is approaching or moving away.
 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
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
Homework
 Page 454 #1-7
 Section 3 Review Page 455 # 1-3, 5-7