Astronomy Test #3

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Which of the following correctly describes
the meaning of albedo?

Reflectivity: (albedo) the fraction of incoming sunlight the planet reflects
Ex: wearing a black shirt

Which of the following worlds has the
greatest difference in temperature
between its "no atmosphere" temperature
and its actual temperature?

Venus would be would be 510° colder without greenhouse effect

What are greenhouse gases?

Visible light passes through atmosphere and warms planets surface

How does the greenhouse effect work?

atmosphere absorbs infrared light from surface, trapping heat

The sky is blue because...

air molecules scatter blue light more than red light

Why is the difference in meaning between
the terms weather and climate?

weather: ever-varying combination of wind, clouds temperature and pressure
climate: long term average of weather, depends on global conditions and is more predictable

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

the release of carbon dioxide from fossil fuels and other sources adds to the greenhouse effect, increasing global warming.

True or False: Without greenhouse gases,
Earth's surface would be frozen over.

true. earth would be below freezing

True or False: Clouds, snow, and ice have
higher albedos than rocks.

they reflect back more solar energy back into space then rocks.

True or False: Earth outgassed as much
carbon dioxide as Venus, but it is locked
up in the oceans and rocks.

TRUE most carbon dioxide is in water and rocks instead of being in the atmosphere

How much energy does Jupiter emit
compared with how much it receives from
the sun?

Jupiter radiates 2x as much energy as it receives from the sun

Why is Jupiter denser than Saturn?

Jupiter is larger in size and in mass because it has greater gravity and it is more compressed.

Why does Jupiter have several distinct
cloud layers?

different chemical compounds make clouds different colors

The fact that most moons always show the
same face to their planet is explained by...

a natural consequence of tidal forces acting on the moons.

What mechanism is most responsible for
generating the internal heat of IO that
drives the volcanic activity?

tidal bulges

Which moon has the most substantial


Which of the Jovian planets have rings?

All of them do.

What is the most important reason why an
ice moon is more likely to be geologically
active than a rocky moon of the same size?

tidal heating can melt internal ice, driving activity.

True or False: Hydrogen exists as a gas,
liquid, and solid within Jupiter.


True or False: Jupiter is slowly shrinking
through gravitational contraction today.


What do asteroids and comets have in

they are small and orbit the sun

An icy leftover planetismal orbiting the sun

a comet!

The combined mass of all the asteroids in
the asteroid belt is...

all asteroids in space wouldn't even make 1 terrestrial planet

Why aren't small asteroids spherical in

The strength of gravity on small asteroids is less than the strength of the rock.

Most meteorites are...

contain at least some iron metal

What is a meteorite?

rock from space that falls
remnants from solar nebula
two types: primitive and processed

True or False: Comet nuclei can be darker
than charcoal.


True or False: A comet that has an orbit
around the sun inclined to the ecliptic
plane by 65 degrees probably originated in
Kuiper Belt.


True or False: Oort cloud comets are
so far from the sun that the gravity of
neighboring stars can alter their orbit.


The first planets around the other sun-like
stars were discovered...

about a decade ago.

Which of the following methods has led
to the most discoveries of massive planets
orbiting near their parent stars?

Doppler technique, radial velocity

How much brighter is a sun-like star than
the reflective light from a planet orbiting
around it?

a billion times brighter

By itself, the Doppler technique provides a measure of a planet's ..

tells us its motion toward and away from us

The composition of a planet can be
determined by ...

Spectroscopic measurements

The transit method of planet detection
works best for ...

transit: when planet crosses in front of a star
big planets in edge-on orbits around around small stars

A planet is detected via the Doppler
technique. The repeating pattern of the
stellar motion tells us ...

measuring stars Doppler shift tells us its motion toward and away from us
current techniques can measure motions as small as 1m/s

How do we think the "hot Jupiters"
around other stars were formed?

They formed as gas giants beyond the frost line and then migrated inwards.
nebular theory: formed outside frost line then migrated after they form
composed the same way as Jupiter, but much closer to a star

Most of the planets discovered around
other stars are more massive than Jupiter.

False. Has a mass similar to Jupiter's.

True or False: Astronomers have
discovered more planets around other
stars than in our solar system.

true. 1/10 of stars have planets

True or False: A planet size can be
determined by observing its transit across
a star.

true, tells planets radius

True or False: A planet's mass can be
determined by observing its transit across
a star.

false? just its radius

The earliest evidence for life on Earth
dates is ...

fossils and carbon isotopes show life probably arose on earth 3.85 million years ago

Which living organisms most resemble the
common ancestor of all life according to
genetic testing?


When did oxygen begin to accumulate in
the atmosphere?

Cyanobacteria or blue-green algae became the first microbes to produce oxygen by photosynthesis, perhaps as long ago as 3.5 billion years ago and certainly by 2.7 billion years ago. But, mysteriously, there was a long lag time - hundreds of millions of years - before Earth's atmosphere first gained significant amounts oxygen, some 2.4 billion to 2.3 billion years ago.

Which of the following is the most
important for maintaining a stable climate
on Earth over the time it took for large
organisms to evolve?

cyanobacteria paved the way for more life forms by releasing oxygen into atmosphere via photosynthesis

What defines the habitable zone around a

~contains the necessities for life, doesn't necessarily have it
~the more massive the star, the larger the habitable zone-higher probability of a planet
~"minimum and maximum zone for water"

At present, what is the primary way that
the search for extraterrestrial intelligence
(SETI) is carried out?

-look for deliberate signals from extra-terrestrials
-we have sent signals ourselves, we'll hear back in 42,000 years, sent to global cluster M13

What is absolutely necessary for living
organisms to survive?

nutrient source + energy (sun) +liquid water

Genetic studies indicate that every living
organism on Earth today shares a common
ancestor. T/F


The rise of life on the planet Earth some
4 billion years ago was made possible, in
part, by the plentiful oxygen in Earth's
early atmosphere. T/F

False! Can't go back to the dinosaur times because there wasn't enough oxygen.

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