ast 103 - test 2

Question 1

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

Answer 1

Gamma ray, x-ray, ultraviolet, visible light, infrared, radio

Question 2

When an atom absorbs a photon containing energy, any of the following can happen except which?

Answer 2

An electron moves from an upper energy level to a lower one

Question 3

Consider an atom of gold in which the nucleus contains 79 photons and 118 neutrons. What is its atomic number and atomic weight?

Answer 3

The atomic number is 79, and the atomic weight is 197

Question 4

How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?

Answer 4

It releases a photon equal in energy to its own energy drop

Question 5

You observe a distant galaxy. You find that a spectral line normally found in the visible part of the spectrum is shifted toward the infrared. What do you conclude?

Answer 5

The galaxy is moving away from you

Question 6

Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes?

Answer 6

The two stars will look like a single point of light

Question 7

Which of the following could not be determined by an observation that uses spectroscopy?

Answer 7

The size of a distant galaxy

Question 8

How are wavelength, frequency, and energy, related for photons of light?

Answer 8

Longer wavelength means lower frequency and lower energy

Question 9

What do astronomers mean by light pollution?

Answer 9

Light pollution refers to light used for human activities that brighten the sky and hinders astronomical observations

Question 10

What is meant by spectral resolution?

Answer 10

It is a measure of how close two spectral lines can be distinguished

Question 11

The planet closest in size to the Earth is?

Answer 11

Venus

Question 12

According to our basic scenario of solar system formation, why do the jovian planets have numerous large moons?

Answer 12

As the growing jovian planets captured gas from the solar nebula, the gas formed swirling disks around them, and moons formed from condensation accretion within these disks.

Question 13

Which of the following statements about the asteroid belt is not true?

Answer 13

The combined mass of all asteroids is roughly the same as the mass of Earth

Question 14

Venus has a higher average surface temperature than Mercury. Why?

Answer 14

Because its surface is heated by an extreme greenhouse effect

Question 15

In what way is Pluto more like a comet than a planet?

Answer 15

It is mostly of rock and ice

Question 16

How is Einstein’s famous equation, E=mc2, important in understanding the Sun?

Answer 16

It explains the fact that the Sun generates energy to shine by losing some 4 million tons of mass each day

Question 17

What percentage of the mass of the solar nebula consisted of elements other than hydrogen and helium?

Answer 17

2%

Question 18

Why did the solar nebular heat up as it collapsed?

Answer 18

As the cloud shrank, its gravitational potential energy was converted to kinetic energy and then into thermal energy

Question 19

What was the frost line of the solar system?

Answer 19

The distance from the Sun where temperatures were low enough for hydrogen compounds to condense into ices, between the present-day orbits of Mars and Jupiter

Question 20

According to our theory of solar system formation, why do we find some exceptions to the general rules and pattens of the planets?

Answer 20

Most of the expectations are the result of giant impacts

Question 21

Which planet has the highest average surface temperature and why?

Answer 21

Venus, because of its dense carbon-dioxide atmoshpere

Question 22

What is the primary reason that astronomers suspect that jovian moons were captured into their current orbits?

Answer 22

Some moons have orbits that are “backwards” (compared to their planet’s rotation) or highly inclined to their planet’s equator

Question 23

According to our present theory of solar system formation, how did Earth end up with enough water to make oceans?

Answer 23

The wanted was brought to the forming Earth by planetestimals that accreted beyond the orbit of Mars

Question 24

The nebular theory of the formation of the solar system successfully predicts all but one of the following. Which one does the theory not predict?

Answer 24

The equal number of terrestrial and jovian planets

Question 25

According to the nebular theory, how did the Kuiper belt form?

Answer 25

It is made of planetestimals that formed beyond Neptune’s orbit and never accreted to form a planet

Question 26

What is the primary reason why a Pluto flyby mission would be cheaper than a Pluto orbiter?

Answer 26

The fuel needed for an orbiter to slow down when it reached Pluto adds a lot of weight to the spacecraft

Question 27

Suppose you start with 1kilogram of a radioactive substance that has half-life of 10 years. Which of the following statements will be true after 20 years pass.

Answer 27

You’ll have 0.25 kilogram of the radioactive substance remaining

Question 28

How does the Sun’s mass compare with that of the planets?

Answer 28

It is a thousand times more massive than all the planets combined

Question 29

In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?

Answer 29

Radio

Question 30

The spectra of most galaxies show redshifts. This means that their spectral lines…

Answer 30

have wavelengths longer than normal

Question 31

Everything looks red through a red filter because

Answer 31

the filter transmits red light and absorbs other colors.

Question 32

At extremely high temperatures (e.g., millions of degrees), which of the following best describes the phase of matter?

Answer 32

a plasma consisting of positively charged ions and free electrons

Question 33

When white light passes through a cool cloud of gas, we see

Answer 33

an absorption line spectrum.

Question 34

You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two?

Answer 34

The line in the faster rotating star is broader.

Question 35

What causes stars to twinkle?

Answer 35

bending of light rays by turbulent layers in the atmosphere

Question 36

Which of the following is farthest from the Sun?

Answer 36

a comet in the Oort cloud

Question 37

What are the main constituents of the jovian planets?

Answer 37

hydrogen and helium