Astronomy HW Qts

Which of the following was not discovered by Galileo using a telescope?

Mars has a polar ice cap similar to Earth

Which terrestrial object shows the least evidence of recent volcanic activity?

Mercury

_________ is the idea that the simplest explanation for a phenomenon is usually the correct one.

Occam's razor

How do the wavelength and frequency of red light compare to the wavelength and frequency of blue light?

Red light has a longer wavelength and lower frequency than blue light

Which is not a reason that we suspect Mars once had liquid water on its surface?

Rovers have detected minerals that must have formed in the presence of liquid water

If you could find a large enough ocean, which one of these planets would float in it?

Saturn

Our universe is approximately 13.7 _________ years old.

billion

Chromatic aberration results from

blue light being refracted more than red light

In practice, the smallest angular size that one can resolve with a 10-inch telescope is governed by the

blurring caused by Earth's atmosphere

What is a planetesimal?

bodies of ice and rock 100 meters or more in diameter

Light has aspects of

both a particle and a wave

What does amplitude reveal about light?

brightness

Which formula denotes how the speed of light is related to its wavelength λ and frequency f?

c = λf

The majority of the energy in our universe is

made up of dark energy that permeates space

Earth's innermost core is solid, not liquid, because

the pressure is too high for the material to be in a liquid state

Human eye diameter is about 8 mm. The Hubble telescope diameter is 2.4 m. The ratio of the light energies from the source collected by the

90,000

The Moon mass is approximately 7.3 10^22 kilogram. Its radius is 1.7 10^6 meters. The escape velocity from the Moon is approximately

0.02 km/s

How far away on average is Earth from the Sun?

1 astronomical unit

A 100-kg astronaut throws a 1-kg wrench with a force of 1 N. What is the acceleration of the wrench after the wrench leaves the astronaut's hand?

1 m/s2

If a radioactive element has a half-life of 10,000 years, what fraction of it is left in a rock after 40,000 years?

1/16

The Sun's magnetic field reverses direction every

11 years

An object was found in a Solar system with a semimajor axis approximately 40 AU. What is its rotational period around the Sun?

250 years

Given that the Sun's effective temperature is 5700K with its radius of 696,340 km. How many hydrogens convert to helium in a second if all the energy of the sun is coming from the hydrogen to helium fusion process?

3.47x10^38

Jupiter is approximately _______ times more massive than Earth

300

The speed of light is approximately

300,000 km/s.

After the Sun, the next nearest star to us is approximately _________ away.

4 light-years

In a simplified nuclear fusion reaction, 4 hydrogens convert to Helium. How much energy released in this process?

4.2x10-12 J

One of the nearest stars is Alpha Centauri, light to travel from Alpha Centauri to us?

4.4 years

The currently broken telescope Arecibo had a diameter of 300 m. Observing at the wavelength of 10 cm, it could resolve objects with the highest resolution of

70 arcsec

An astronaut who weighs 700 N on Earth is located in empty space, very far from any other objects. Approximately what is the mass of the astronaut?

70kg

The average distance between Earth and the Sun is 1.5 * 10^11 m, and light from the Sun takes approximately _________ to reach Earth.

8 minutes

Which of the following is false?

A scientific theory is an undisputed fact.

Two rocks (call them S and T) are released at the same time from the same height and start from rest. Rock S has 20 times the mass of rock T. Which rock will fall faster if the only forces involved are each rock's mutual gravitational attraction with Earth?

Both rocks will fall at the same rate.

The Sun rotates once every 25 days relative to the stars. The sun rotates once every 27 days relative to the Earth. Why are these two numbers different?

Earth moves in its orbit during this time

We experience seasons because

Earth's equator is tilted relative to the plane of the solar system.

Leap years occur because

Earth's orbital period is 365.24 days

True facts:

Everyone on Earth observes the same phase of the Moon on a given night, In some phases, the Moon can be observed during the day, A full Moon can be seen on the eastern horizon at sunset.

Who of the following was a proponent of the heliocentric model of the solar system?

Galileo, Copernicus, Newton

We have direct evidence for the current existence of water on the surface of which terrestrial object?

Ganymede

How did Ptolemy "fix" the geocentric system?

He introduced epicycles.

We can determine how the density changes with radius in the Sun using

Helioseismology

_________ hypothesized that planetary motions could be explained by a force arising from the attraction between the mass of the planet and the Sun that decreased with the square of the distance between them.

Isaac Newton

How does the speed of light traveling through a medium (such as air or glass) compare to the speed of light in a vacuum?

It is always less than the speed of light in a vacuum

If the carbon dioxide in Earth's rocks were suddenly released into its atmosphere, what would happen?

It would cause a runaway greenhouse effect

If the Sun instantaneously stopped giving off light, what would happen on the day-side of Earth?

It would get dark 8.3 minutes later

Suppose by some mysterious process that the nuclear fusion rate in the core of the Sun were to increase. What would happen to the appearance of the Sun?

It would grow larger but stay at the same temperature, making it more luminous, it would grow larger but cooler

If an object is moving in a circular orbit at a constant speed, which of the following is false?

Its acceleration is zero

________ was the first person to introduce a mathematical heliocentric model of the Solar System from which accurate predictions could be made of planets' positions.

Johannes Kepler

The largest volcanic mountains in the Solar System are found on

Mars

What do astronomers mean when they say that the Sun makes energy by hydrogen burning?

The Sun is fusing hydrogen into helium and releasing energy

In the absence of air friction, a 0.001-kg piece of paper and a 0.1-kg notebook are dropped from the same height and allowed to fall to the ground. How do their accelerations compare?

The accelerations are the same.

Which of the following is true about a comet that is on an elliptical orbit around the Sun?

The comet's speed is greatest when it is nearest the Sun.

If a collapsing interstellar cloud formed only a protostar without an accretion disk around it, what would happen?

The forming protostar would be rotating too fast to hold itself together

Which of the following is not a characteristic of the early Solar System, based on current observations?

The initial composition of the solar nebula varied between its inner and outer regions.

Venus and Earth probably formed with similar amounts of carbon dioxide in their secondary atmospheres. Which of the following is true?

The majority of Earth's carbon is now bound up in rock, whereas Venus's remains in its atmosphere

If the Sun stopped nuclear fusion in its core, how long would it take for its luminosity to change significantly?

about 100,000 years

Earth is located approximately

about halfway out from the center of the Milky Way.

Why are Jupiter and Saturn not perfectly spherical?

They rotate rapidly

Why did the terrestrial planets lose the majority of the gas in their primary atmospheres?

They were too hot and their escape velocities too low to hold onto them

The time it takes a planet to complete one full orbital revolution is commonly known as its

period

What is the difference between visible light and X-rays?

Wavelength; X-rays have a shorter wavelength than visible light

If Earth's axis were tilted by 5° instead of its actual tilt, how would the seasons be different than they are currently?

Winters would be warmer

Gravity is

a fundamental force, a mutually attractive force.

What is a protostar?

a large ball of gas not yet hot enough at its core to be a star

Which of the following photons carries the smallest amount of energy?

a microwave photon, whose wavelength is 10−2 m

The time it takes light to cross Neptune's orbit is closest to which of the following?

a night's sleep

An atmospheric window is

a region of the electromagnetic spectrum that can reach the ground

Which of these stars would have the biggest redshift?

a star moving at high speed away from you

Which of these objects would exhibit an absorption spectrum?

a thin, cool gas cloud that lies in front of a hotter blackbody

If we could increase the quantum efficiency of the human eye, it would

allow humans to see better at night or other low-light conditions

How often do leap years occur?

almost every 4 years

The Maunder Minimum was a 60-year period when

almost no sunspots occurred on the Sun

If you observe an isolated hot cloud of gas, you will see

an emission spectrum

One of the central assumptions in astronomy is that the physical laws of nature

are the same everywhere in the universe.

When you look at the visible surface of a gas giant planet, you are looking at that planet's

atmosphere

The main greenhouse gases in the atmosphere of the terrestrial planets are

carbon dioxide and water vapor

Kepler's second law says that if a planet is in an elliptical orbit around a star, then the planet moves fastest when the planet is

closest to the star

The hottest layer of the solar atmosphere is the

corona

Which of the layers of the Sun is located the farthest from the center of the Sun?

corona

The majority of the mass in our universe is made up of

dark matter

As wavelength increases, the energy of a photon _________ and its frequency _________

decreases; decreases

Cameras that use adaptive optics provide higher spatial resolution images primarily because

deformable mirrors are used to correct the blurring due to Earth's atmosphere

Which of the following is a bound orbit?

elliptical, hyperbolic

The balance of energy in the solar interior means that

energy production rate in the core equals the rate of radiation escaping the Sun's surface

A hypothesis is an idea that is

falsifiable with current technology, potentially falsifiable with future technology

In the absence of the greenhouse effect, the water on the surface of Earth would

freeze

The net effect of the proton-proton chain is that four hydrogen nuclei are converted to one helium nucleus and _________ are released

gamma ray photons, positrons, and neutrinos

Which of the following lists different types of electromagnetic radiation in order from the shortest wavelength to the longest wavelength?

gamma rays, ultraviolet, visible, infrared, radio waves

The early universe was composed mainly of which two elements?

hydrogen and helium

The majority of the Sun's energy comes from

hydrogen fusion

If the radius of an object's orbit is halved, and angular momentum is conserved, what must happen to the object's speed?

it must be doubled

One reason to prefer a reflecting over a refracting telescope is

its lack of chromatic aberration, its shorter length for the same aperture size, its lack of an aperture limit, its lighter weight for larger apertures

What is the reason Mercury has so little gas in its atmosphere?

its mass is small, it has a high temperature ,it is close to the sun, its escape velocity is low

Whether or not a planet is composed mostly of rock or gas is set by

its mass, its temperature, its distance from the star when it formed

In the radiative zone inside the Sun, photons are transported from the core to the convective zone over a time of

many thousands of years

The force of gravity that an object has is directly proportional to its

mass

The giant planets are made primarily of

molecular hydrogen and helium

The diameter of the Moon is

more than half the distance across the continental United States.

If the Sun is located at one focus of Earth's elliptical orbit, what is at the other focus?

nothing

When two atomic nuclei come together to form a new species of atom, this is called

nuclear fusion

The net result of the proton-proton chain of nuclear reactions is that four protons are converted into

one helium nucleus, as well as energy, positrons, and neutrinos

Which of the following processes did not contribute gas to Earth's secondary atmosphere?

oxidation

___ in our atmosphere is a direct consequence of the emergence of life

oxygen

_________ in our atmosphere is a direct consequence of the emergence of life

oxygen

If photosynthesis were to disappear on Earth,

oxygen would disappear from the atmosphere

The fact that the speed of light is constant as it travels through a vacuum means that

photons with longer wavelengths have lower frequencies

Retrograde motion is seen when ____________ due to Earth's motion

planets change the direction in which they move across the night sky

As energy moves out from the Sun's core towards its surface, it first travels by ______, then ______, and then ______

radiation; convection; radiation

The Moon undergoes synchronous rotation, and as a consequence the

rotational period of the Moon equals the orbital period of the Moon around Earth

According to the conservation of angular momentum, if an ice-skater who is spinning with her arms out wide slowly pulls them close to her body, this will cause her to . . .

spin faster

When the northern hemisphere experiences fall, the southern hemisphere experiences

spring

Newton's first law states that objects in motion

stay in motion unless acted upon by an unbalanced force.

During which season (in the Northern Hemisphere) could you see the Sun rising from the furthest north?

summer

Sunspots appear dark because they have _________ than those of the surrounding gases

temperatures that are lower

The Local Group is the environment around

the Milky Way that contains a few dozen galaxies.

A partial lunar eclipse occurs when

the Moon passes through part of the Earth's shadow.

Solar and lunar eclipses are rare because

the Moon's orbital plane is tipped by 5.2° relative to Earth's orbital plane.

The ecliptic is defined by the motion of _________ in the sky.

the Sun

What is a secondary atmosphere?

the atmosphere that remains after the planet has formed

Tidal forces are caused by

the difference between the strength of the gravitational pull of the Moon and Sun on either side of Earth

What is a primary atmosphere?

the gas captured during the planet's formation

One can argue that the heliocentric model of the Solar System was more natural than the geocentric model, based on

the observed retrograde motions of the planets. Earth's motion

If you go out at exactly 9 P.M. each evening over the course of 1 month, the position of a given star will move westward by tens of degrees. What causes this motion?

the revolution of Earth around the Sun

Nuclei of atoms are held together by

the strong nuclear force

Why can you see fainter stars with an 8-inch telescope than you can see with your naked eye?

the telescope collects light over a larger area

Astronauts orbiting Earth in the space shuttle experience so-called weightlessness in space because

they are in constant free fall around Earth.

The major advantage CCDs have over other imaging techniques is that

they have a higher quantum efficiency, they have a linear response to light, they yield output in digital format, they operate at visible and near-infrared wavelengths

In the absence of a greenhouse effect, what would happen to Earth's oceans?

they would freeze over

A theory is

tied to known physical laws, able to make testable predictions, a hypothesis that has withstood many attempts to falsify it

Which of the following is not a reason to put a telescope in space?

to get closer to the stars, to avoid weather on Earth

The greenhouse effect is the

trapping of infrared radiation by the atmosphere

Astronomers can use ground-based telescopes to observe the majority of which of the following parts of the electromagnetic spectrum?

visible and radio

Astronomers can use ground-based telescopes to observe in the majority of which of the following parts of the electromagnetic spectrum?

visible, ultraviolet, and infrared

The presence of gases such as carbon dioxide and water vapor in a planet's atmosphere is direct evidence of _____ in a planet's history

volcanic activity

The color of visible light is determined by its

wavelength

Which of the following properties of an astronaut changes when he or she is standing on the Moon, relative to when the astronaut is standing on Earth?

weight

The day with the smallest number of daylight hours over the course of the year for a person living in the northern hemisphere is the

winter solstice (Dec. 22)