Astronomy Midterm #2

Front 1

The only difference between visible light and radio waves is that

Back 1

radio waves have longer wavelengths than visible light.

Front 2

Two sets of waves can combine with each other to produce a resultant wave. This phenomenon is called?

Back 2

interference

Front 3

What do all kinds of electomagnetic energy have in common?

Back 3

all have the same speed in a vacuum

Front 4

The tendency of light to bend at the edge of an opening is called?

Back 4

diffraction

Front 5

Which of the following effects demonstrates the wave-nature rather than the particle-nature of light?

Back 5

diffraction & interference

Front 6

Which of the following lists the various forms of radiation in order of -longest- to -shortest- wavelength?

Back 6

visible, ultraviolet, X-ray, gamma rays

Front 7

The Moon is about 400,000 km from Earth. About how long would it take a radar signal from Earth to reach the Moon?

Back 7

1.3 seconds

Front 8

The _____ the frequency of light, the ______are the photons of which it is composed.

Back 8

higher, more energetic

Front 9

When an electron jumps from an excited state to the ground state in an atom,

Back 9

a photon is emitted

Front 10

When an atom changes from a lower to a higher energy level, the process is called

Back 10

excitation

Front 11

Suppose you have a detector that captures 1000 photons with a wavelength of 100 Angstroms each. How many photons would you need to collect in order to have the same total amount of energy if the photons had a wavelength of 20 Angstroms?

Back 11

200

Front 12

In an atom that absorbs a photon,

Back 12

an electron moves to a larger orbit.
an electron moves to a higher energy level.
the atom may become ionized.
it is possible it will spontaneously change its energy state again soon.

Front 13

Wien's Law

Back 13

relates the temperature of a radiating object to the wavelength at which it will emit the most energy.

Front 14

When a cool gas cloud intervenes between an observer and a source of light that emits light of all wavelengths, the observer would see..

Back 14

an absorption spectrum characteristic of the gas cloud

Front 15

Ionization means that an atom..

Back 15

loses an electron

Front 16

Who discovered that most of the universe is hydrogen?

Back 16

Cecilia Payne-Gaposchkin

Front 17

Which of the following has the stellar spectral classes correctly ordered from coolest to hottest?

Back 17

MKGFABO

Front 18

You would expect to find the highest degree of ionization in the atmosphere of

Back 18

an O-type star.

Front 19

We can measure the temperatures of stars from a study of their

Back 19

spectra & colors

Front 20

The spectral type of the sun is..

Back 20

G

Front 21

What quantity has the biggest influence in determining the spectral type of a star?

Back 21

surface temperature

Front 22

A star whose parallax is 0.1 second of arc is at a distance of

Back 22

10 parsecs

Front 23

If a star is observed from Earth to have a parallax of 0.25 seconds of arc, what would the parallax be if the star were observed from telescopes in Saturn's orbit, which is 10 times larger?

Back 23

10 times larger, 2.5 seconds of arc

Front 24

In the Hertzsprung-Russell (H-R) diagram, a star less luminous and hotter than the Sun would be found

Back 24

below and to the left of the Sun

Front 25

How much more energy does each unit area of a 25,000 K star radiate than a 5,000 K star?

Back 25

625 times

Front 26

If two stars A and B have the same surface temperature, yet star A has a lower luminosity than star B, then

Back 26

A must be smaller than B

Front 27

The constellation Gatorius consists of five stars, all of which appear equally bright to the eye. Star A is an O supergiant, B is an M giant, C is an M main sequence star, D is a G main-sequence star, and E is a B white dwarf. Which star is intrinsically the most luminous?

Back 27

A

Front 28

Into which category do the majority of stars fall?

Back 28

main sequence

Front 29

The Hertzsprung-Russell diagram is

Back 29

a graph of stellar luminosity versus surface temperature

Front 30

How do Saturn's rings rotate?

Back 30

slowly in the outer regions and rapidly in the inner regions

Front 31

Jupiter gives off more energy than it receives from the Sun. What is the source of this excess energy?

Back 31

internal heat left over from its formation

Front 32

What is Jupiter's Great Red Spot thought to be?

Back 32

a violent and long-lived storm, like a cyclone or hurricane

Front 33

From the observed densities of the Jovian planets, we infer that they are made primarily of ?

Back 33

hydrogen

Front 34

What makes it possible for astronomers to calculate the masses of the Jovian planets?

Back 34

the presence of moons

Front 35

Which of the following quantities determines whether a planet will exhibit seasons?

Back 35

axial tilt

Front 36

What do astronomers infer about Jupiter from the presence of its magnetic field?

Back 36

the presence of a rotating core of liquid metallic hydrogen in the interior.

Front 37

Jupiter's Galilean satellites have higher densities than the satellites of the other Jovian planets. We can infer that the Galilean satellites contain more _____ than the satellites of the other Jovian planets.

Back 37

rocky silicate materials like the Moon

Front 38

Which features characterize Io?

Back 38

volcanic flows

Front 39

What features characterize Europa?

Back 39

an ice-covered ocean of water

Front 40

What might you reasonably conclude about the origin of small Jovian satellites that orbit in a direction opposite to the largest satellites?

Back 40

they are captured comets

Front 41

What features characterize Titan?

Back 41

the presence of an atmosphere

Front 42

What is at least one reason why rings are thought to be sharp-edged, rather than fuzzy-edged?

Back 42

The presence of shepherd satellites

Front 43

Which of the following planets would come closest to floating in a giant interplanetary bathtub filled with water?

Back 43

Saturn

Front 44

Why is the interior of Io so hot?

Back 44

Jupiter exerts strong tidal forces on it.

Front 45

A friend of yours argues that Pluto is probably an escaped satellite of one of the giant planets. What piece of evidence could you cite that would best argue -against- this idea?

Back 45

Pluto has a moon of its own

Front 46

Which of the following is -not- characteristic of the terrestrial planets?

Back 46

short rotation periods

Front 47

Why did proto-terrestrial planets have a different chemical composition than proto-jovian planets?

Back 47

High temperatures in the inner solar system made the difference.

Front 48

Which one of the following statements concerning comets is correct?

Back 48

Comets are observed in all directions on the celestial sphere.

Front 49

Suppose you wanted to study objects whose chemical make-up was most like that of the solar system at the time it formed. Thus, you would want to study objects that had undergone the least amount of chemical change. Which one of the following would contain such material and thus be the best to study?

Back 49

the comets

Front 50

What is the source of particles that impinge on the Earth during a meteor shower?

Back 50

material evaporated from and strewn out along the orbits of comets

Front 51

Which one of these planets has the most extreme seasonal variations?

Back 51

Uranus

Front 52

In which of the following characteristics is there NOT a MAJOR difference between Pluto and the Jovian planets?

Back 52

distance from the sun

Front 53

If a comet has a very eccentric (i.e. very elliptical) orbit and has an orbital period of 1000 years, what is its maximum distance from the Sun?

Back 53

200 AU

Front 54

What is the Oort cloud?

Back 54

A nearly spherical distribution of comets, that have been flung out from the inner Solar system by the Jovian planets