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106 Cards in this Set

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The earliest evidence for life on Earth dates to

about 3.8 billion years ago

For most of the history of life on Earth, the dominant life forms have been

Single-Celled organisms

What is absolutely necessary for all living organisms (not just animals) to survive?


When we analyze whether a world is a possible home to life, the key thing we look for is

the past or present existence of liquid water.

The habitable zone is the region where water is a liquid on a planet’s surface. How does the greenhouse effect change where this is?

It moves it further from the Sun

The chemical element that is considered key to making the raw materials for life is


The only place outside of Earth where there is irrefutable evidence for (ancient, microbial) life is

there is no irrefutable evidence for life beyond Earth

Other than Mars, the next most likely candidates for life in the solar system are

the icy moons of the jovian planets.

Why do astronomers suspect that there is chance that life may exist on Jupiter's moon Europa?

The presence of abundant liquid water, one of the basic requirements of life on the Earth.

Recent exoplanet discoveries suggest that our galaxy has at least ten billion (10 000 000 000) Earth-like planets in the habitable zones of their stars.

10 million

What is outgassing?

Adding gas to an atmosphere through volcanism.

A planet is discovered with a rich oxygen atmosphere but no sign of life. Why or why not is this surprising?

Surprising. Rich oxygen atmospheres can only be produced by living organisms.

In a gas at a temperature of 300 K, how does the speed of the molecules depend on their mass?

More massive molecules move slower.

Consider a planet orbiting a star like ours. This planet has a mass that is 1.2 times the mass of the Earth, and it is 1.5 AU from its star. Which of these is a plausible atmosphere for this planet?

Thick atmosphere (40 bars) of carbon dioxide with a surface temperature of 450 K

What do we mean by a runaway greenhouse effect?

a greenhouse effect that keeps getting stronger until all a planet's greenhouse gases are in its atmosphere

The carbon cycle is a "negative feedback cycle". The "negative feedback" part means

Small changes in the amount of carbon dioxide tend to return to the original equilibrium temperature.

Consider the following feedback system: the Earth’s polar caps. If they begin to melt, this will change the Earth’s reflectivity. This reflectivity change will affect the temperature. What type of feedback system is this?

Positive feedback

All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space?

Mars lost any global magnetic field that it may once have had.

Venus may have started with an ocean's worth of water. Where is its water now?

The water was lost when ultraviolet light broke apart water molecules and the hydrogen escaped to space.

Why does the burning of fossil fuels increase the greenhouse effect on Earth?

Burning releases carbon dioxide into the atmosphere.

As a submarine goes down in the ocean, the pressure


If you make the surface a planet brighter (by increasing the reflectivity) what will this do to its surface temperature?

Decrease it

The Sun emits mostly visible light. The Earth’s surface is cooler, so it emits mostly infrared light. Imagine that the atmosphere transmits visible light but absorbs infrared light. What will this do to the sunlight coming in? What will it do to the infrared radiation from the Earth going out?

Incoming sunlight passes through atmosphere, outgoing infrared absorbed

Which of the following statements about Earth's troposphere is not generally true?

It is the layer of the atmosphere in which ozone absorbs dangerous ultraviolet light from the Sun.

X rays from the Sun's corona

are absorbed in the earth's thermosphere.

Why should we expect rising air at the equator and descending air at the poles?

Solar heating at the equator causes the air to rise

Which of the following is not caused by the Coriolis effect on Earth?

Water going down a drain swirls in opposite directions in the Northern and Southern hemispheres.

Is this a sensible statement? Additional heating of the Earth’s surface is likely to result in more (or stronger) storms.

Yes. Storms are caused by convection, which is caused by surface heating

Why are there few deserts along the Earth's equator?

There tends to be rising air at the equator which creates clouds and hence rainfall.

Which of the following best describes the geological history of the Moon?

Early in its history, it suffered many impacts and experienced some volcanism and tectonics, but it now has little geological activity at all.

"The cratering history of the Moon tells us that impact cratering still happens on the Earth.”

Yes. Earth and Moon are both still hit, but the Moon does not hide craters as Earth does.

Which has the older surface?

Heavily cratered Martian highlands

Many Mars volcanoes are shield volcanoes. What does this imply about the lava that produced them?

The lava is intermediate viscosity

Which composition allows a world to be geologically active even at relatively cool temperatures?

Ice, because ice melts at a lower temperature

What drives the motion of the continental plates on Earth?

convection cells in the mantle

If crust and mantle rocks flow at a rate of centimeters per year, how far could they travel in billions of years of Earth’s history? Remember that there are 100,000 centimeters in a kilometer.

More than 10,000 km, part way around the Earth.

Deep trenches in the ocean mark places where

one plate slides under another, returning older crust to the mantle.

What is the biggest impactor that is statistically likely to hit the Earth in your lifetime (100 years)?

Between 10 and 100 m

If an impactor with the potential for mass extinction typically happens once in 100 million years, how many such impacts would we expect to have occurred in the history of life on earth (about 4 billion years)?

40 times

What do we mean when we say that the terrestrial worlds underwent differentiation?

At a time when their interiors were molten, denser materials sank toward their centers and lighter materials rose toward their surfaces.

Which of the following planets could be made mainly of hydrogen and helium?

400 Earth masses, 1.5 g/cm3

Jupiter and the other jovian planets are sometimes called "gas giants." In what sense is this term misleading?

They really contain relatively little material in a gaseous state. Much more of their mass is liquid, metallic, or in strange high-pressure states that we don’t naturally find on Earth.

How do the jovian planet interiors differ?

All have cores of about the same mass, but differ in the amount of surrounding hydrogen and helium.

Which internal heat source still generates heat within the terrestrial worlds today?

heat from radioactive decay

Which of the following best describes why the smaller terrestrial worlds have cooler interiors than the larger ones?

The smaller size means that heat doesn't have to travel as far to get from the center to the surface.

When a large comet or asteroid hits the surface of the Moon, it

Explodes on impact, producing a large circular crater.

Would you expect a typical impact on the Moon to be more or less energetic than a typical impact on Earth?

Less energetic on the Moon

Volcanism is more likely on a planet that

has high internal temperatures.

Which of the following describes tectonics?

the disruption of a planet's surface by internal stresses

Should we be surprised to discover the following solar system? It has 7 planets, four of these planets orbit in the same plane, while the other 3 are in orbits that are roughly perpendicular to the others.
Yes, this is surprising. Planets should all orbit in the same direction if they form in the same disk.
In general, the colder the temperature:
the more materials are in solid form.
Which of the following lists the ingredients of the solar nebula from highest to lowest percentage of mass of the nebula?
light gases (H, He), hydrogen compounds (H2O, CH4, NH3), rocks, metals
Because small-scale accretion is caused by electrostatic forces, it is effective on
Solids only
The steps in the process of formation of the large, outer planets were
accretion of ice-rich planetesimals to form a large core, followed by gravitational capture of hydrogen and helium gas.
Jovian moons are large enough to accrete gas efficiently.
Outside of the frost line, what materials condensed to form solids in the disk around the Sun?
Hydrogen compounds, rocks, and metals
Why are the inner planets made of denser materials than the outer planets?
In the inner part of the nebula only metals and rocks were able to condense because of the high temperatures, whereas hydrogen compounds, although more abundant, were only able to condense in the cooler outer regions.
Which new idea has been added into our theory of solar system formation as a result of the discoveries of extrasolar planets?
Jovian planets can migrate inward from the orbits in which they are born.
What do meteorites reveal about the solar system?

They reveal that the age of the solar system is approximately 4.6 billion years.

What is the correct order of the planets from largest to smallest mass?
Jupiter, Saturn, Neptune, Uranus, Earth, Venus, Mars, Mercury.
Which of the following is a characteristic of the terrestrial planets?
They all have solid, rocky surfaces.
Uranus is “tipped over” so that its equator is roughly 90 degrees to its orbit. What should this do to seasons on Uranus?
There will be extreme seasonal changes
Which of the following is not a characteristic of the jovian planets when compared with the terrestrial planets?
solid, icy surfaces
Why aren't small asteroids spherical in shape?
The strength of gravity on small asteroids is less than the strength of the rock.
Suppose you view the solar system from high above Earth's north pole. Which of the following statements about planetary orbits will be true?
All the planets orbit counterclockwise around the Sun.
Which of these would make it easier to see an exoplanet?
Planet is far from its star
We measure the mass of an extrasolar planet by
using Newton's law of gravity, using the measured distance from the star and its gravitational pull on the star.
If you must observe several transit events to announce a planet candidate, which will you be able to announce soonest?
A planet in a close orbit
Which combination of observations would allow you to find the density of an extrasolar planet?
Radial velocity and imaging/Radial velocity and transit
An atom is now known to consist of a
small, massive, electrically charged core with electrons surrounding it.
Which of the following would you have to change to turn lead into a different chemical element?
The number of protons.
Consider a helium balloon and all of its contents. As it is inflated, what happens to its mass, its volume, and its density?
Mass increases. Volume increases. Density decreases.
As the temperature goes down, most gases go through what phase transitions?
First into a liquid then into a solid
The wavelength of a wave is
the distance between two adjacent peaks of the wave.
Light behaves as:
Both particles and waves
What makes radio waves different from visible light?
Radio waves have lower energy.
Why does a red shirt look red?
The red shirt reflects red light and absorbs other colors.
The primary thing we can learn about a gas from studying the spectral lines it emits or absorbs is its
The key property of a hypothesis that makes it scientific is that it should be
Once a scientist (or group of scientists) finds an interesting result, what process must they go through to have their results published in a scientific journal?
The result must be sent to another scientist who will look for errors.
Consider lifting a ball straight up into the air at a constant speed. There are two forces acting on the ball: gravity and the push from your hand. Which force is larger?
The two forces are the same.
Two identical spacecraft are accelerated by rocket engines. The second spacecraft has twice as much mass as the first. Which has a higher acceleration?
The first spacecraft: it has less mass
Suppose you lived on the Moon. Which of the following would be true?
Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth.
A car moving at 30 miles/hour has roughly 100,000 J of kinetic energy. You need to keep your foot on the gas to maintain your speed (assume a flat road). The gas you burn represents 500 J of chemical energy every second. After 5 minutes, how much kinetic energy does your car have?
100,000 J

Why is it more dangerous to put your hand in boiling water (212 F) than in a hot oven (350 F)?

The water has more thermal energy than the air in the oven.

Consider swinging on a swing. How do kinetic energy (KE) and gravitational potential energy (GPE) change as you swing?

GPE is maximum at the top of the arc, while KE is maximum at the bottom of the arc.

The formula E = mc2 tells us that

A small amount of mass can be converted into a large amount of energy.

Over the course of one night, an observer at any given location on the Earth sees the constellations gradually shift across the sky from east to west. This is caused primarily by

The spin of the Earth on its own axis

Are there stars that never appear to set as seen from Southern California?

Yes, stars near the North Star appear to circle around this point without setting.

In the northern hemisphere, the stars rise in the East, set in the West and spin counter-clockwise around the North celestial pole. In the southern hemisphere the stars rise in the

East, set in the West and spin clockwise around the South celestial pole.

Orion is visible on winter evenings but not summer evenings because of

the location of the earth in its orbit.

The Earth experiences seasons because

The tilt of the Earth's spin axis causes different hemispheres to get more or less sunlight.

Imagine a planet whose spin axis is perpendicular to its orbital plane. How would you describe its seasons?

constant through the year.

Why do we see different phases of the Moon?

Because more (or less) of the half of the Moon that is lit up by the Sun becomes visible as the Moon orbits the Earth

A friend exclaims that a few months ago she saw the full moon overhead at noon. Is this possible?

No, the full Moon is never overhead at noon.

The Earth's shadow falling on the Moon is the reason we see

lunar eclipses

A person on Earth sees a total solar eclipse. What would someone else standing on the side of the Moon facing the Earth see at this time? The Earth's

day side, with a dark spot that moves across it.

Our solar system consists of

the Sun and all the objects that orbit it.

Sound travels at a speed of 300 meters per second. In analogy to the light-year, what does 1 sound-minute equal?

The distance traveled by sound in 1 minute.

The Sun is

An ordinary star.

If our sun is expected to last about 6 billion years longer, then turn to be a planetary nebula for several thousand years, about how much of the rest of its life will our sun be a planetary nebula?

A millionth

Arrange the following items according to size, from the smallest to the largest.

Earth, Sun, giant star, solar system, galaxy

In what sense are we "star stuff"?

We are made from the debris of previous generations of stars.

The formation of our solar system occurred

Around 4.6 billion years ago, billions of years after the universe formed.

What does 3.67 x 103 mean?


When we convert from kilometers to meters, we multiply by 1000 m/ 1 km. We can do this because

this fraction is equal to one.