Unit E Section 3.3

Question 1

two ways of measuring distances indirectly,

on the ground or in space.

Answer 1

Triangulation and parallax

Question 2

What is Triangulation?

Answer 2

Triangulation is based on the geometry of a triangle.

By measuring the angles between a baseline and the target object (such as a tall tree or a water tower), you can determine the distance to that object.

Question 3

What must you know when doing triangulation?

Answer 3

-you must know the length of one side of the triangle
(the baseline)

-the size of the angles created when imaginary lines are drawn from the ends of the baseline to the same points on the distant object

Question 4

What is Parallax?

Answer 4

Parallax is the apparent shift in the position of a nearby object when the object is viewed from two different places

Question 5

Why do astronomers use parallax?

Answer 5

Astronomers use a star’s parallax (that is, its apparent shift in position relative to the background stars) to determine what angles to use when they triangulate the star’s distance from Earth.

Question 6

When triangulation calculations are made, the longer the baseline, the…….

Answer 6

the more accurate the results

Question 7

white light is actually a combination of
all colors (the “rainbow” colors)

Answer 7

White light can be separated into its component colours by being shone through a prism. The result is bands of colour, which together are referred to as the visible spectrum

Question 8

Why do different stars have dark bands in distinct

sequences and thicknesses on their spectra?

Answer 8

this happened because the various elements in a star absorb light in different ways.

As a result, each element creates its own black-line “fingerprint.”

Question 9

How do astronomers figure out a star’s composition?

Answer 9

Astronomers compare the spectrum of a star with known spectra of elements to determine the star’s composition.

Question 10

spectrometer?

Answer 10

An instrument used when comparing the spectrum of a star with known spectra of elements to determine the star’s composition

Question 11

What is a pitch?

Answer 11

the frequency of sound waves.

Question 12

Why does the pitch of a siren go louder when it is near a person?

Answer 12

This occurs because the sound wavelengths become compressed in front of the vehicle as to the vehicle approaches, causing the pitch to rise.

the vehicle moves away, the wavelengths behind the vehicle are no longer squeezed.

Question 13

What is a pitch?

Answer 13

the frequency of sound waves.

Pitch refers to the shift in the sound waves of a moving object.

Question 14

What form does light travel?

Answer 14

light also travels in waves

Question 15

Changes in light waves can be used to do what?

Answer 15

Changes in those waves can be used to measure how fast and in what direction a light-emitting object is
moving

Question 16

What shifts in the light waves of a moving star

Answer 16

The position of the dark bands in the light spectrum

Question 17

What happens in the spectrum when wavelengths become compressed:

Answer 17

The spectrum of an approaching star shows

the dark lines shifting to the blue end of the spectrum as the light’s wavelengths become compressed

Question 18

What happens when the wavelengths stretch

out:

Answer 18

In the spectrum of a star moving away from Earth, the dark lines shift to the red end as the wavelengths stretch out.

Question 19

What does the amount of that shift shown in the spectrum?

Answer 19

The amount of that shift shows up in observations of a star indicates the speed at which the star is approaching or receding.

Question 20

The Doppler effect comes into play in a number of everyday applications. Such as:

Answer 20

One of the most common is the radar gun used by police to detect drivers who are traveling above the speed limit.

Question 21

What does the Doppler effect refer to?

Answer 21

to the change in frequency of sound, light, and other waves, which results from the relative motion between an observer and the source of the waves