Astronomy Exam 3

What do we know about the rings around jovian planets?

1. All four jovian planets have rings 2. They are made of vast numbers of particles, each circling the planets according to Kepler's laws 3. Rings are fed with new material from impacts on small moons within the rings

Choose all that apply about comets:

1. Comets grow tails only when they approach the Sun. 2. Comets in plane of the Solar System come from Kuiper belt. 3. Comets with randomly oriented orbits come from Oort cloud.

Which of the following molecules represent greenhouse gases? Choose all that apply:

1. H20 2. CO2 3. CH4

Choose the properties below that best describe the surface and structure of Mercury:

1. No atmosphere 2. Large differences in temperature 3. No pressure

Choose the properties below that best describe the surface and structure of Venus

1. Primarily carbon dioxide atmosphere 2. High pressure compared to Earth 3. High temps

The image shows a thick dust cloud observed at two different wavelengths. Choose all the correct answers that you can infer from it

1. Stars seen in panel B must be located behind the dust cloud. 2. Background stars seen through the cloud appear redder than they really are, thus the name "reddening". 3. The dust cloud is completely opaque to visible light (panel A), but is transparent to longer near-infrared wavelength (panel B).

What arguments led to the decision to exclude Pluto from the family of planets?

1. The Kuiper belt from which some comets come contains objects as large as or even larger than Pluto. 2. Large objects in the Kuiper belt (Pluto, Eris, etc.) have tilted, elliptical orbits and icy compositions like those of comets. 3. Pluto has a relatively large moon, Charon (about half its size), while all other planets are significantly larger than their moons.

Choose all that apply relative to Saturn's rings:

1. They are made of numerous small, individual particles. 2. They orbit over Saturn's equator. 3. Rings are very thin due to frequent collisions between particles.

What makes a planet habitable?

1. size 2. distance from sun

What unique features on Earth are important for life?

1. surface of liquid water 2. climate stability 3. plate tectonics 4. atmospheric oxygen

Which of the following surface features are seen on Mars?

1. volcanoes 2. carters 3. huge canyons

What is a meteor?

A "shooting star": the glowing trail of hot gas and vaporized debris left by friction as an object moves through the Earth's atmosphere

What does Pluto most resemble?

A comet

What is the Great Red Spot?

A huge, spinning vortex larger than the Earth in Jupiter's atmosphere

Jupiter's Great Red Spot is basically

A large, long lasting storm

While explaining the formation of the Solar System we discussed the fact that higher temperatures will allow molecules to move faster. Also, the more massive the particles, the lower the velocity they will have. Given this information, what conditions would you think would be best to retain very light elements in a planetary atmosphere?

A planet with a high mass and low temperature.

At their centers, all jovian planets have cores made of

A solid mixture of rock

The surface of Venus has an almost uniform distribution of craters and the number of craters is much less than that observed on the Moon. What can we say about the age of the surface of Venus?

All of the surfaces of Venus are approximately the same age, all being much younger than the Moon's.

If there are at least a million asteroids, how did spacecraft like Galileo survive their trip through the asteroid belt?

Although there are many asteroids, they are widely spaced.

If everything in the Solar System is moving around, why do the Perseid meteors repeat regularly around August 11th?

Because the Earth in its orbit intersects the same swarm of meteor particles at the same time each year.

Visible starlight passing through a dust cloud can be affected in the following ways

Brightening

Astronomers estimate that the runoff channels seen on Mars must be at least 3.9 billion year old. How do they estimate ages like this?

By counting impact craters in the regions containing these channels.

The main component of the atmosphere of Mars is

Carbon dioxide

The main component of the atmosphere of Venus is

Carbon dioxide

What means greenhouse effect?

Certain molecules in the atmosphere let visible sunlight through, but trap escaping infrared photons emitted by the heated surface.

Saturn's ring system is so thin because of

Collisions among ring particles

What kind of spectrum do we get from an emission nebula?

Emission line spectrum

Although Jupiter and Saturn have very strong magnetic fields, there is no evidence for a magnetic field in Neptune and Uranus.

False

The ring systems around the planets are similar to a large, smooth, solid, rotating sheet

False

There is no evidence for liquid water ever being present on the surface of any terrestrial planet besides the Earth.

False

What is the difference between an emission and a reflection nebula?

Generally, emission nebulas appear red, and reflection nebulas look blue

Io exhibits a great deal of volcanic activity, indicating that its interior is very hot. What is Io's heat source thought to be?

Io is subject to a strong and changing gravitational force from Jupiter that distorts its shape and heats it by internal friction.

Which of the following is NOT a way that Jupiter differs from terrestrial planets?

It has many more craters from early collisions.

Jupiter does not have a large metal core like Earth. How can it have a magnetic field?

It has metallic hydrogen inside, which circulates and makes a magnetic field.

What is unusual about Triton?

It orbits its planet backwards

Hydrogen and helium are the primary constituents of

Jovian planets

Choose the correct answer:

Jupiter's magnetic field is stronger than the Earth's magnetic field

Most short period comets are thought to originate from the

Kuiper Belt

What planet can best be describe as "cool, thin atmosphere, some cratering with little evidence for present geologic activity."

Mars

The main asteroid belt is located between the orbits of

Mars and Jupiter

Which of the following defines density?

Mass divided by volume

What planet can best be described as "large temperature variations, no atmosphere, heavily cratered with no evidence for present geologic activity."

Mercury

Which of the following planets has a difference of temperature on its surface of over 500 K?

Mercury

Which of the following are the terrestrial planets?

Mercury, Venus, Earth, Mars

What is the name of the luminous phenomenon observed?

Meteor

Neptune displays a deep blue color. What can be the reason for that?

Methane in the atmosphere absorbs red light and scatters (reflects) blue light.

Why are Uranus and Neptune so blue?

Methane in their atmospheres absorb red light and reflect blue light from the Sun

Among planets Neptune has the third largest mass in the Solar System but Uranus has the third largest size. What does this imply about the two planets?

Neptune is denser than Uranus

The main component of the atmosphere of Earth is ______

Nitrogen

In what way is the Moon similar to the Earth?

None of the above

What process is replenishing the heat lost through the surface of the Earth to maintain its internal heat?

Nuclear fission - larger radioactive elements break apart to produce smaller elements and energy.

What do we conclude if a planet has few impact craters of any size?

Other geological processes have erased craters

Which fundamental property of a terrestrial planet has the greatest effect on its level of volcanic and tectonic activity?

Planets size

Which is the dominant process that continues to contribute to Earth's internal heat?

Radioactive decay of unstable isotopes

Asteroids are composed mainly of

Rocky material

Why is Venus so hot?

Runaway greenhouse effect

Which of the jovian planets has density smaller than the density of water?

Saturn

Sirius has an apparent magnitude m = -1.4. Betelgeuse has an apparent magnitude m = 0.4. Which one is brighter from the point of view of an observer located on the Earth?

Sirius

A planet is discovered with a small (but measurable) magnetic field and has a density of 4500 kg/m3 (or 4.5 g/cc). The planet spins every 30 hours. What is the most likely interior composition of the planet? (Recall the source of magnetic field for our Earth and the typical density of rocky terrestrial worlds

Some rock and some liquid metal

Why are there two tails to some comets?

The first tail, called the "gas or plasma tail," is pushed out by the solar wind. The second tail, called the "dust tail," is pushed out by the solar radiation.

Why is the inner core solid even though it is hotter than the outer liquid core?

The great pressure at Earth's center forces the atoms in the core together, causing it to solidify

In class we have been talking about the force of gravity. The atmosphere of a planet is held to the planet by the gravitational pull between the molecules in the gas and the planet. Which statement is most accurate?

The greater the mass of the planet, the greater the gravitational force.

Although the Earth and Venus are similar in many ways, what one main difference caused the very different atmospheric conditions on these planets?

The location of the planets in the Solar System.

The densest part of a comet is

The nucleus

What means differentiation when talking about the interior structure of planets?

The process by which gravity separates materials according to density.

Why does Mars appear red?

The surface rocks of Mars have some iron oxide, giving them a reddish color.

What evidence do we have that the surface features on Mercury were not formed during recent geological activity?

They were heavily cratered

The only moon in the Solar System that has a very thick atmosphere is

Titan

A planet with a density of 3300 kg/m3 would be composed primarily of rocky material.

True

The main source of the volcanic activity on Io is interior heating due to the tidal forces exerted by Jupiter.

True

What planet can best be describe as "hot, dense atmosphere, few craters with some evidence for recent geologic activity."

Venus

Which planet of the Solar System has its day longer than its year?

Venus

The Martian polar caps are composed of frozen

Water and carbon dioxide

The rings of the outer planets consist of

billions of small particles (of various sizes) that all orbit the equator of each planet

The Earth has very few craters on its surface compared to the Moon because

erosional and geologic processes on the Earth have erased many of the craters.

When a periodic comet leaves its dusty debris behind in its orbit, the Earth can intercept this debris and

have a meteor shower as the dust burns up.

Apparent magnitude (m) is an indicator of:

how bright the star appears to be at its actual (real) distance

Absolute magnitude (M) is an indicator of:

how bright the star would appear to the eye if it were placed at a standard distance of 10 parsecs

One of the key reasons professional astronomers today are interested in comets is that they

icy pieces left over from the time that our solar system formed that can give us clues about that early time

Our Sun has an apparent magnitude of -26.8. Its absolute magnitude is 4.8. This implies that the Sun

is much closer than 10 parsecs

Where is most of the CO2 that has outgassed from Earth's volcanoes?

locked up in rocks

The innermost part of our Earth is

solid metal due to the high pressures inside of the Earth.

In its overall composition, the Moon most resembles

the earths crust and mantle

If a star has an apparent magnitude m = 1.0 and an absolute magnitude M = 4.0, the conclusion is

the star is at a distance smaller than 10 parsecs

Some jovian planets give off more energy than they receive because

they are still slowly contracting after formation

The Earth's atmosphere is transparent to which of the following waves?

visible, radio