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Intro Astronomy > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

The colors of the rainbow, or of white light passed through a prism, from longest to shortest wavelength are

A

red, orange, yellow, green, blue, indigo, violet.

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2
Q

Who discovered the invisible infra-red (or heat) portion of the solar spectrum?

A

Sir William Herschel

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3
Q

What is the frequency of the shortest wavelength light that can be detected by the average human eye?

A

400nm

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4
Q

Interstellar space (the space between the stars) is filled with extremely low-density hydrogen gas. In the vicinity of a hot star, this gas can be heated to a very high temperature. This hot, low-density gas will

A

emit light at specific wavelengths characteristic of hydrogen.

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5
Q

Which of the following types of electromagnetic radiation has the lowest energy?

A

infrared radiation

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6
Q

Which of the following types of electromagnetic radiation has the greatest energy?

A

gamma-rays

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7
Q

Which of the following types of electromagnetic radiation has the greatest energy?

A

gamma-rays

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8
Q

The ____ of a gas is a measure of the average speed of the particles (atoms or molecules) in the gas.

A

Temperature

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9
Q

Which of the following types of electromagnetic radiation has the smallest frequency?

A

Radio

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10
Q

Long wavelength visible light

A

will appear red in color to the average human eye.

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11
Q

A Spectrograph is an instrument that reveals

A

the spectral DNA Fingerprint of elements in the Heavens

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12
Q

When a rod of metal is heated intensely, its predominant color will

A

change from red through orange to white and then to blue.

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13
Q

The chemical makeup of a star’s “surface” is usually determined

A

by spectroscopy of the light emitted by the star.

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14
Q

An absorption spectrum is also called a bright line spectrum.

A

False

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15
Q

The dark absorption lines in the solar spectrum are caused

A

by a cooler layer of gas overlying the hot solar surface, which contains many elements, including hydrogen, helium, magnesium, calcium, iron, etc.

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16
Q

Diagram 6-2 illustrates a light source, a gas cloud, and three different lines of sight. Along which line of sight would an observer see an absorption spectrum?

A

3

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17
Q

Diagram 6-2 illustrates a light source, a gas cloud, and three different lines of sight. Along which line of sight would an observer see a continuous spectrum?

A

1

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18
Q

Diagram 6-2 illustrates a light source, a gas cloud, and three different lines of sight. Along which line of sight would an observer see an emission spectrum?

A

2

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19
Q

We plot the intensity of the radiation emitted from an object at a certain temperature versus its wavelength. As we increase the temperature, the wavelength at which the spectrum peaks becomes shorter and shorter. This is an example of

A

Wien’s Law

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20
Q

A visible light spectrum of the Sun reveals many dark absorption lines. These lines are caused by [photon] absorption which takes place in the

A

photosphere

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21
Q

What is a diffraction grating?

A

A piece of glass, or plastic, with thousands of closely spaced, parallel grooves

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22
Q

The light from a small amount of a particular chemical element, such as H or He, when vaporized into a gas, on Earth, is found to consist of

A

a pattern of narrow, bright emissions at wavelengths that are specific to the element and different for each element

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23
Q

What evidence do we have that the Sun contains the element, iron?

A

Solar spectra show absorption in spectral lines that are characteristic of iron and are unique to it.

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24
Q

Each element has its own set of characteristic absorption lines because

A

electron energy levels differ for each element

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25
Q

When astronomers look for evidence of hydrogen gas in the spectra of the Sun, or other stars, the positions of the spectral “lines” due to hydrogen

A

will always be in the same characteristic pattern as seen in the laboratory, a pattern unique to hydrogen, but will appear black due to absorption in the cool atmosphere of the star.

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26
Q

The photosphere of the Sun is

A

the visible “surface” of the Sun.

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27
Q

Granulation or the mottled appearance of the whole solar “surface” is an indication of what physical process at work in the Sun?

A

Convective motion of gases in the photosphere.

28
Q

A supergranule on the Sun is

A

a large area of slowly rising and falling gas containing hundreds of ordinary granules.

29
Q

Where is the chromosphere on the Sun?

A

It is the layer above the visible surface of the Sun.

30
Q

The highest temperatures in the Sun are found in the

A

solar interior.

31
Q

What is the solar wind?

A

Material from the corona, accelerated out into space

32
Q

The heliosphere is

A

the protective region containing the Sun and planets created by the solar wind, which prevents penetration by much of the radiation from outside the solar system.

33
Q

Sunspots are

A

cooler, darker regions on the Sun’s surface.

34
Q

The major feature that distinguishes a sunspot from other regions on the Sun is

A

its very powerful magnetic field.

35
Q

What is the average length of time from one maximum in the number of sunspots on the Sun to the next maximum?

A

11 years

36
Q

Galileo observed the phenomenon of solar rotation in the early 1600s by

A

measuring the motion of sunspots across the solar surface the Sun.

37
Q

What is the rotation period of our Sun?

A

About one rotation per month

38
Q

What is the Zeeman effect?

A

The splitting of spectral lines emitted by atoms within a magnetic field

39
Q

Intense magnetic fields have been found to exist in sunspots by the observation of what specific physical effect?

A

The Zeeman effect, the splitting of spectral absorption lines

40
Q

Although we speak of the solar “surface,” the Sun is so hot that it has neither liquid nor solid matter anywhere inside it.

A

True

41
Q

The energy source for our Sun is?

A

Thermonuclear fusion of H and He with resultant release of energy

42
Q

Thermonuclear fusion is

A

the combining together of light nuclei (e.g., hydrogen) to produce heavier nuclei (e.g., helium) with the resultant release of energy.

43
Q

The core of our Sun, in which all of the Sun’s thermonuclear energy is produced, takes up about

A

¼ of the Sun’s radius.

44
Q

In terms of its total hydrogen-burning lifetime, the Sun is

A

about half-way through its life.

45
Q

The most probable theory for formation of the Sun & solar system is that

A

the Sun and planets slowly condensed to their present form from a collapsing, rotating nebula cloud of gas and dust cloud.

46
Q

The most common elements in the universe are

A

hydrogen and helium, with small amounts of heavier elements.

47
Q

What fraction of the mass of the Earth is made up of the elements hydrogen and helium?

A

Less than 1%

47
Q

Hydrogen and helium together account for what percentage of the total mass of all the matter in the universe?

A

98%

48
Q

Most of the mass of our bodies comes from heavy elements such as carbon and oxygen. This fact immediately tells us that

A

the solar system did not form directly from the material created by the Big Bang.

49
Q

Where, theoretically, was all the hydrogen in the universe formed?

A

In the Big Bang, at the very ‘beginning’ of the Universe

50
Q

There is very little hydrogen or helium in the inner part of the solar system today. We believe the reason for this is that

A

the intense radiation from the early Sun “drove” [quoting the textbook] the light elements out of the inner solar system.

51
Q

The process of accretion in planetary formation is

A

the slow accumulation of solid particles by gravity and collision into larger, solid objects.

51
Q

The birthplace of our Sun and planets (and of other stars and maybe their planets) is thought to have been

A

in the condensation (collapsing) of a rotating nebula of cool gas and dust clouds

52
Q

The correct sequence of planets in our solar system, from our Sun outward, is

A

Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

53
Q

In August 2006, Astrophysicists gathered at a symposium in Prague, Czech Republic and made a new definition of what constitutes a “major planet.” Because of their decision what planet has been demoted to “minor planet” status?

A

Pluto

54
Q

Where is the Asteroid Belt located in our solar system?

A

Most asteroids orbit our Sun in a belt about 1.5AU wide between the orbits of Mars and Jupiter.

55
Q

What are comets?

A

Comets are chunks of rock and ice. Beyond the orbit of Neptune lies hundreds of millions of these objects.

56
Q

What is the Kupier Belt?

A

A belt of comets that abound in the million in orbit past Pluto out to 50 AU from our Sun.

57
Q

What is the distance between the Earth and the nearest star?

A

1AU

58
Q

Strong evidence for the existence of planetary systems in the process of formation around other stars comes from

A

periodic wobbling of the positions and spectral line displacements of several nearby stars.

59
Q

____ is a set of rules that describes how atoms and subatomic particles behave.

A

Quantum Mechanics

60
Q

Our Sun has a surface temperature of approximately 5800 K (or 10,000 F). At what wavelength does the maximum energy radiated by our Sun occur? Hint: Our sun’s dominant wavelength is in the yellow region.

A

520 nm

61
Q

Which of the following cannot be determined from the spectrum of a star?

A

tangential (perpendicular to line of sight) velocity

62
Q

The radiation emitted from a star has a maximum intensity at a wavelength of 300 nm. What is the surface temperature of this star?

A

10,000 K

63
Q

Photons of blue light

A

have a greater energy than photons of red light.

Intro Astronomy (4 decks)

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