Astronomy Exam #2 for the 10-Week Session

Astronomy Exam #3 Fall 2010

Name______

1)In the space below contrast the properties of the Terrestrial and Jovian planets.

2)The minor planet Pluto has a diameter of 2.38x108cm and a mass of 1.25x1025 g. Calculate its density and discuss its composition using the table of bench mark densities to the right.

3)There is a number line below which is marked in AU. On that number line mark the positions of the eight planets from the Sun, which is at 0AU, as precisely as you can. You may use the first letter of the planet’s name as an identifier.

4)Which of the planets listed below has a mass of just about 1/10 the mass of the Earth?

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A)Mercury

B)Mars

C)Earth

D)Uranus

E)Venus

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5)Which of the values listed below best represents the mass of Jupiter?

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A)1,000 Earth masses

B)300 Earth masses

C)100 Earth masses

D)30 Earth masses

E)10 Earth masses

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6)For which of the reasons below is Venus sometimes called “Earth’s twin”?

A)The atmosphere of Venus contains N2 and O2 just like the Earth.

B)The mass and radius of Venus is just about the same as those of the Earth.

C)Venus has one moon orbiting it just as the Earth does.

D)The Venus spins at the just about the same rate as the Earth so that their day lengths are about equal.

E)Venus has a strong magnetic field like the Earth

7)Which of the following is NOT a characteristic of the Jovian planets?

A)They have very few, if any, natural satellites.

B)They all have large quantities of gas.

C)They are primarily made of hydrogen and helium.

D)Their orbits are separated by relatively large distances.

E)They all have ring systems.

8)Which of the ages below corresponds to the age of our solar system?

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A)1 Million Years

B)64 Million Years

C)4.6 Billion Years

D)10 Billion Years

E)13.1 Billion Years

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9)What are the two most abundant gases in an interstellar cloud?

______and ______

10)The image below is meant to represent the solar nebula. In the boxes on the figure insert the appropriate values for the diameter and thickness of the solar nebula

11)State or identify the source of energy that provided initial heating of the solar nebula even before the Sun was formed.

A)Friction of dust grains rubbing against each other within the cloud
Radioactive decay of heavy elements like uranium

B)Nuclear fusion of light elements like hydrogen

C)Nearby stars heated the nebula with their star-light

D)Gravitational collapse of the nebular gas was converted into heat

12)The image to the right is of the nucleus of Comet Hartley 2. The nucleus is only about 2 km long. Comets like this are examples of which of the following objects?

A)Interstellar dust grain

B)Solar Nebula

C)Planetesimal

D)Dwarf Planet

E)UFO

13)In a few sentences, explain why planetesimals had more material to grow from in the outer parts of the Solar System than in the inner part.

14)In a few sentences, explain why the composition of the planets abruptly changes between the inner and outer solar system.

15)Which of the processes listed below was responsible for planet growth?

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A)Accretion

B)Coalescence

C)Collisions

D)Condensation

E)All the above

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16)In a few sentences, explain how the Jovian planets could begin with the accumulation of solid ice and rock and yet end by becoming surrounded by huge envelopes of hydrogen-rich gases.

17)Scientists are still unsure as to the origin of the Earth’s oceans. Circle the hypotheses below that are currently be investigated regarding the origin of the Earth’s oceans. (Circle all that apply)

A)Comets delivered water to fill the oceans to the Earth after it had formed.

B)The water came from water rich icy planetesimals that the Earth formed from.

C)The water is outgassed from volcanoes that release the small amount of water bound in the origin rocks the Earth formed from.

D)The water was captured as it evaporated off the Sun’s surface.

18)In a few sentences, explain why Saturn’s moon Titan has an atmosphere, but Earth’s moon does not even though both moons have nearly identical gravity fields and escape velocities.

19)Which of the processes below terminated the formation of the planets in our solar system?

A)All the gas, dust and ice were consumed by the planets leaving no more material left to grow with.

B)A nearby supernova removed all the unbound gas, dust and ice from our system thus starving the planet formation process.

C)All the rock fell into the Sun and the ice melted and evaporated into space, again, starving the planet growth process.

D)The initial burst of energy from the newly ”turned on” Sun swept the solar system clear of the raw materials needed to grow planets.

E)The seventh day ended.

20)Below are listed ten of the 496 known planets around other stars. The table contains the planet name, mass, semi-major axis of its orbit and its eccentricity.

21)What is the average mass of these planets in Jupiter masses and Earth masses?

Average mass = ______= ______

22)The average semi-major axis of these planet’s orbits is 1.14 AU. In a few sentences characterize these planets given their average mass and average semi-major axis and state how they appear to be different from the planetary systems the Solar Nebula Model would predict.

23)Which of the ten planets above has the most circular orbit?

Planet Name ______

24)Which of the planets above seems to be most similar to our planetary system?

Planet Name ______

25)Examine the characteristics of the planet HD 154672b. Propose a mechanism, in a few sentences, that would place this planet into the orbit it currently has assuming that it formed farther from its star.

26)Examine the characteristics of the planet HD 11506b. It is 2.43 AU from its parent star. The distance to the star is 169 ly. What is the angular separation between the planet and its parent star in degrees and arcseconds?

27)The radial velocity curve of a star known as HD 160691. Asuming that the star is similar to our Sun, what can you say (quantitatively) regarding the planet(s) that surround this star.

28)What is the ratio of radii between the largest and smallest of the planets in our solar system? See Table to the right

29)The mass of the Sun is closest to which of the values below?

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A)300 Earth masses

B)3,000 Earth masses

C)30,000 Earth masses

D)300,000 Earth masses

E)3,000,000 Earth masses

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30)The Sun is approximately how much larger in radius than the Earth?

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A)100 Earth radii

B)1,000 Earth radii

C)10,000 Earth radii

D)100,000 Earth radii

E)1,000,000 Earth radii

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31)The density of the Sun is closest to the density of ….

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A)Iron, 8 g/cm3

B)Rock, 5 g/cm3

C)Water, 1 g/cm3

D)Ice, 0.9 g/cm3

E)Air, 0.001 g/cm3

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32)The surface temperature of the Sun is….

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A)32,000 K

B)15,500 K

C)7,200 K

D)5,800 K

E)1,600 K

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33)The core of the Sun has a temperature of…

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A)Unknown

B)15 Million K

C)50 Million K

D)100 Million K

E)1.4 Billion K

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34)The Sun can be functionally divided into two layers. Describe the physical characteristics of the two layers in the space below.

35)In a sentence or two, describe the functional difference between the core and envelope. In other words, what purpose does the core serve in the star’s function and what purpose does the envelope serve in the star’s function?

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