Question 13 out of 3 points

 What do asteroids and comets have in common?Answer

Selected Answer:  Most are unchanged since their formation in the solar

nebula.

Correct Answer:  Most are unchanged since their formation in the solar

nebula.

Response Feedback:

 Correct, both are left over from the formation of the Solar System

Question 20 out of 3 points

A constellation isAnswer

Selected Answer:

 d.

members of a single star cluster

Correct Answer:

 c.

stars at varying distances in the same part of the sky

Response Feedback:

Incorrect, the stars in a constellation are not necessarily members of a single star cluster.  stars in a single cluster are approximately the same age and distance.

Constellations are just pretty pictures in the sky created by our ancestors to tell stories.

Question 30 out of 3 points

We currently know of approximately how many exo-planets?Answer

Selected Answer: 900

0

Correct Answer: 900

Response Feedback:

Incorrect, see the exo-planets encyclopedia for the latest numbers

Question 43 out of 3 points

A G2V star and a K2V star have the same:Answer

Selected Answer: none of the

above

Correct Answer: none of the

above

Response Feedback:

Correct, remember for main sequence stars the mass, radius, luminosity and temperature are all related (and all are lower as you get to later spectral types).

Question 50 out of 3 points

Why does the fusion of hydrogen release energy to power the Sun and stars?Answer

Selected Answer:

 c.

fusion breaks up hydrogen molecules, releasing energy.

Correct Answer:

 b.

fusion combines 4 hydrogen atoms into one helium which has less mass than 4 protons

Response Feedback:

Incorrect, this mass difference powers the stars, think Einstein's equation E = m c2, the energy released is proportional to the mass difference.

If helium was more massive than the 4 hydrogen atoms the stars would not shine.

Question 60 out of 3 points

You observe a star cluster with a main-sequence turn-off point at spectral type G2 (the same spectral type as the Sun). What is the age of this star cluster?Answer

Selected Answer: 4.6 billion years.

Correct Answer: 10 billion years.

Response Feedback:

Incorrect, stars like the Sun live 10 billion years

Question 73 out of 3 points

 Which of the following is not a characteristic of the inner planets?Answer

Selected Answer:

 They all have substantial atmospheres.

Correct Answer:  They all have substantial

atmospheres.

Response Feedback:

 Correct, only Venus and Earth have significant atmospheres

Question 80 out of 3 points

Remembering that the surface temperature of the Sun is ~6000K, a red giant would have a temperature of:Answer

Selected Answer: 30,000

K

Correct Answer: 3000 K

Response Feedback:

Incorrect, a red giant like Arcturus is ~1/2 the (surface) temperature of the Sun.

A 30,000 K star is an O star like Rigel and the Earth is ~300 K.

Question 93 out of 3 points

A star like the Sun will:Answer

Selected Answer:

 a.

become a white dwarf

Correct Answer:

 a.

become a white dwarf

Response Feedback:

Correct, after it uses all of its hydrogen fuel a star like the Sun will expand into a red giant, then eventually after running out of its core helium become a planetary nebula and then a white dwarf

Question 103 out of 3 points

What was the material out of which the Solar System formed primarily made of?Answer

Selected Answer: Mostly hydrogen and helium with a small amount

of dust grains

Correct Answer: Mostly hydrogen and helium with a small amount

of dust grains

Response Feedback:

Correct, the Universe is still mostly hydrogen and helium (from the Big Bang)

Question 113 out of 3 points

Your mass would be approximately (                   )  times larger than it is here on Earth if you were on a 1 Solar mass white dwarf:Answer

Selected Answer: the

same

Correct Answer: the

same

Response Feedback:

Correct, your mass is always the same.  Note that the weight increases as the gravitational force increases.

Question 123 out of 3 points

If the Sun were to suddenly expand to be 10 times its current size of ~0.0047 AU but keep the same mass, the Earth would:Answer

Selected Answer: stay in the same

orbit

Correct Answer: stay in the same

orbit

Response Feedback:

Correct, the force on the Earth would be unchanged since the mass of the Sun is unchanged, so the orbit would not change.

Note this would not be true if the Sun were to expand to be larger than the Earth's orbit of course.

Also note that orbital distances are defined from both object's centers, so while the Earth in some sense is

"closer" to the Sun's surface, its distance from the Sun's center and hence its orbital distance is unchanged.

Question 133 out of 3 points

Consider two stars, A and B, with the following apparent and absolute magnitudes:

m(A) = -2 (apparent magnitude)M(A) = 10 (absolute magnitude)

m(B) = 3 (apparent magnitude)M(B) = 5 (absolute magnitude)

which is more luminous?

Answer

Selected Answer:

 a.

A appears brighter, but B is actually brighter

Correct Answer:

 a.

A appears brighter, but B is actually brighter

Response Feedback:

Correct, A's apparent magnitude of -2 (a smaller number) means it appears brighter but B's absolute magnitude of 5 (versus 10 for A) means it is in intrinsically brighter.

Question 140 out of 3 points

 When we see a region of a planet that is not as heavily cratered as other regions, we conclude thatAnswer

Selected Answer:  the planet formed after the age of bombardment and missed out on getting hit by leftover

planetesimals.

Correct Answer:  the surface in the region is younger than the surface in more heavily cratered regions.

Response Feedback:

 Incorrect, the regions that have been reformed via vulcanism, erosion, etc most recently have fewer craters

Question 150 out of 3 points

Incandescent light bulbs have a temperature of ~2700 K, this means that their light is emitted mostly:Answer

Selected

Answer: at optical wavelengths

Correct Answer: at infrared

wavelengths

Response Feedback:

Incorrect, the cooler temperature (relative to the Sun) means that these bulbs emit most of their light at longer - infrared - wavelengths.  This is why they are so inefficient.

Question 163 out of 3 points

If we see a high mass Ostar in the Andromeda galaxy tonight, we know that:Answer

Selected Answer: it will have already gone (Type II)

supernova

Correct Answer: it will have already gone (Type II)

supernova

Response Feedback:

Correct, remember that an O star has lifetime of order 1 million years, and so even before the light from an O star reaches us from Andromeda (2 million light years away) the star has been born, evolved, and exploded as a Type II SN before any being in the MIlky Way can see it.

Question 170 out of 3 points

 What happens to the core of a star after it ejects a planetary nebula?Answer

Selected Answer:  It becomes a neutron

star.

Correct Answer:  It becomes a white

dwarf.

Response Feedback:

 Incorrect, this is the path stars like the Sun take in becoming white dwarfs

Question 180 out of 3 points

Open clusters contain approximately ( )   stars:Answer

Selected

Answer: 1,000,000,000

Correct Answer: 1,000

Response Feedback:

Incorrect, open clusters typically contain fewer stars (1,000) than the globular clusters (~100,000-1,000,000) which formed early in the galaxies history.

Question 193 out of 3 points

About how old is the Solar System?Answer

Selected Answer: 5 billion

years

Correct Answer: 5 billion

years

Question 203 out of 3 points

Approximately how many Earth's fit inside the Sun:Answer

Selected Answer:

 c.

1,000,000

Correct Answer:

 c.

1,000,000

Response Feedback:

Correct, the volume of the Sun is ~1,000,000 times that of the Earth.

Question 213 out of 3 points

The MK-spectral types OBAFGKM must represent a sequence of:Answer

Selected Answer: decreasing

temperatures

Correct Answer: decreasing

temperatures

Response Correct, the first letter of the spectral type is related to the

Feedback:

effective surface temperature of the star.  Not that (for example) M stars can have a variety of radii and hence luminosities (as L=T4R2), and that a supergiant has a larger mass than a giant or main sequence M star.

Question 220 out of 3 points

The Sun will most likely never become a nova or type Ia supernova because such events only happen to stars thatAnswer

Selected Answer: are much more massive than

the Sun

Correct Answer: are in close binary systems

Response Feedback:

Incorrect, novae and type Ia supernovae occur in binary systems where one member is a white dwarf.

Remember that high mass stars become type II supernovae.

Question 230 out of 3 points

 On a Hertzsprung-Russell diagram, where on the main sequence would you find stars that have the greatest mass?Answer

Selected Answer:  lower

right

Correct Answer:  upper left

Response Feedback:

 Incorrect, O stars have the largest mass

Question 243 out of 3 points

A main sequence star's luminosity comes from:Answer

Selected Answer:

 a.

fusion of hydrogen into helium in the core

Correct Answer:

 a.

fusion of hydrogen into helium in the core

Response Feedback:

Correct, the main sequence is when a star uses nuclear fusion reactions to convert hydrogen into helium in the core of the star.

Question 253 out of 3 points

Type II supernovae occur in evolved O and B stars because they:Answer

Selected Answer: can fuse elements heavier than helium and thus have

large iron cores

Correct Answer: can fuse elements heavier than helium and thus have

large iron cores

Response Feedback:

Correct, remember that iron has the highest binding energy of all elements and so a star cannot extract energy from fusing iron into heavier elements.

Question 263 out of 3 points

Compared to stars like the Sun, B stars like RigeL have:Answer

Selected Answer: lifetimes much shorter than

the Sun

Correct Answer: lifetimes much shorter than

the Sun

Response Feedback:

Correct, hot, luminous massive stars like Rigel burn through there fuel much more quickly and thus have lifetimes much shorter than the Sun.

Question 270 out of 3 points

 How thick are Saturn's rings from top to bottom?Answer

Selected Answer: a few kilometers

Correct Answer:  a few million

kilometers

Response Feedback:

 Incorrect, the rings are incredibly thin

Question 28

3 out of 3 points

After the collapse began were all parts of the Solar Nebula the same temperature, and if not which part was hottest?Answer

Selected Answer: Not all the same temperature, and the inner parts

were the hottest.

Correct Answer: Not all the same temperature, and the inner parts

were the hottest.

Question 293 out of 3 points

 Why do asteroids and comets differ in composition?Answer

Selected Answer:  Asteroids formed inside the frost line, while comets formed

outside.

Correct Answer:  Asteroids formed inside the frost line, while comets formed

outside.

Response Feedback:

 Correct, asteroids formed where the pre-Solar nebula was too hot for ices to form

Question 303 out of 3 points

Type-II supernovae occur when:Answer

Selected Answer:

 d.

a massive star collapses after running out of fuel

Correct Answer:

 d.

a massive star collapses after running out of fuel

Response Feedback:

Correct, a Type II supernova is when the core of a massive star collapses, releasing energy that explodes the rest of the star

Question 313 out of 3 points

 The core of the Sun isAnswer

Selected Answer:  much hotter and much denser than its

surface.

Correct Answer:  much hotter and much denser than its

surface.

Response Feedback:

 Correct, remember our discussion based upon the average density and the luminosity relationship with temperature and radius

Question 323 out of 3 points

You observe two stars over the course of a year (or more) and find that both stars have measurable parallax angles. Star X has a parallax angle of 1 arc-second. Star Y has a parallax angle of  1/4 of an arc-second. How do the distances to the two stars compare?Answer

Selected Answer: star Y is 4 times further

away

Correct Answer: star Y is 4 times further

away

Response Feedback:

Correct, the parallax angle is equal to (distance)-1, so the more distant star has a smaller parallax, and if the parallax is 4 times smaller then it is 4 times further away.

Question 333 out of 3 points

Hydrostatic equilibrium means that:Answer

Selected Answer: stars have a higher temperature and pressure in their

centers to support the mass of their outer layers

Correct Answer: stars have a higher temperature and pressure in their

centers to support the mass of their outer layers

Response Feedback:

Correct, the concept of hydrostatic equilibrium implies that a star must have a higher pressure in its center to support the weight of the outer layers.

Question 340 out of 3 points

An M-star which is 1/1000th the luminosity of the Sun an 1/10th its mass should live approximatelyAnswer

Selected Answer:

 b.

1 billion years

Correct Answer:

 d.

1 trillion years

Response Feedback:

Incorrect, since the amount of energy it puts out is 1/1000th that of the Sun but it has only 1/10th the fuel, it should last 100 times longer- since the Sun lives 10 billion years an M star should live 1 trillion years.

Question 350 out of 3 points

 On a Hertzsprung-Russell diagram, where would you find red giant stars?Answer

Selected Answer:  lower

right

Correct Answer:  upper

right

Response Feedback:

 Incorrect, red giants are cool (to the right) and bright (toward the top)

Question 360 out of 3 points

Remembering that the Sun has a surface temperature of  approximately 5,800 K, a main sequence A star like Vega will have a temperature of approximately:Answer

Selected Answer: 5,800

K

Correct Answer: 10,00

0K

Response Feedback:

Incorrect, an A star is slightly hotter than the Sun, a star at ~50,000K is an O star (the hottest stars) and all of the other choices are as cool or cooler than the Sun so would not fit an A star.

Question 370 out of 3 points

Imagine a star which has the same luminosity as the Sun but which has a surface temperature that is twice that of the Sun. You would

then expect that a planet identical to Earth orbiting at 1 AU from this star would:Answer

Selected Answer: be ~4x hotter than the Earth

Correct Answer: be approximately the same temperature

as the Earth

Question 380 out of 3 points

Pluto is now classified as a dwarf planet because:Answer

Selected Answer: its moon Charon is too massive, so the center of mass of

the system is outside Pluto

Correct Answer: it is in the Kuiper belt

Response Feedback:

Incorrect, Pluto has not "cleared" its orbit.  Note that it croses Neptune's orbit not that of Uranus.

Question 390 out of 3 points

We can determine the age of a globular cluster by:Answer

Selected Answer: counting the number of neutron stars in the cluster.

Correct Answer: finding the spectral types of the most luminous main

sequence stars.

Response Feedback:

Incorrect, the most massive/luminous main sequence stars left are the ones whose lifetime is less than the age of the cluster, so the cluster must be just older than that age.

All of the stars with lifetimes less than the age of the cluster will have evolved off the main sequence already.

Question 403 out of 3 points

How do the planets near the Sun differ from those farther out?Answer

Selected Answer: The ones nearest the Sun are

generally smallest.

Correct Answer: The ones nearest the Sun are

generally smallest.

Question 60 out of 3 points

Type II supernovae occur in evolved O and B stars because they:

Answer

Selected Answer:

form white dwarf stars in binary systems

Correct Answer:

can fuse elements heavier than helium and thus have large iron cores

Response Feedback:

Incorrect, remember that iron has the highest binding energy of all elements and so a star cannot extract energy from fusing iron into heavier elements.

Question 110 out of 3 points

About how old is the Solar System?

Answer

Selected Answer:

5 trillion years

Correct Answer:

5 billion years

Question 130 out of 3 points

 How thick are Saturn's rings from top to bottom?

Answer

Selected Answer:

 a few hundred kilometers

Correct Answer:

 a few million kilometers

Response Feedback:

 Incorrect, the rings are incredibly thin