Astronomy Exam 1

Why does the angle of the Sun's rays matter in regard to Earth's seasons?

They are more spread out if they strike at an angle

Different cultures created different calendars because

They used different definition of the day, month, and year

Despite the fact that the Sun's gravitational force on Earth is almost 200 times stronger than the Moon's gravitational force on Earth, the strength of the Moon's tidal force on Earth is more than twice as strong as the Sun's. Why is that?

Tidal forces depend on the difference between the gravitational force on the near side of Earth compared to the far side

The celestial equator is :

directly above the Earth's equator

A light-year is a unit commonly used in astronomy as a measure of

distance

The time it takes a planet to complete its orbit around the Sun is determined by its

distance from the Sun

When the Sun, Earth, and a plaent all lie along a straight line, the planet is at

either opposition or conjunction

When Earth catches up to a slower-moving outer planet and passes it in its orbit, the planet

exhibits retrograde motion

Tides on Earth occur only in the oceans (true or false)

false

A superior planet is one that is

farther from the Sun than Earth

Imagine two objects moving away from you. Object A is faster than object B. You will observe that the light

from object A has a larger shift in frequency

One of the nearest stars is Alpha Centauri, whose distance is 4.4 light-years. The time it takes light to travel from Alpha Centauri to us is

4.4 years

If the plane of the Moon's orbit were the same as the ecliptic (the plane of the Earth's orbit), we would have

One solar eclipse and one lunar eclipse each month

Which of the following is not true about orbits

Orbits are always circular

Galileo observed that Venus had phases that correlated with its size in his telescope. From this information, you may conclude that Venus

Orbits the sun

Just after sunset, a star appears near the eastern horizon. Where will it appear to be after 6 hours

Overhead

Just after sunset, a star appears near the eastern horizon. Where will it appear to be after 6 hours?

Overhead

If you measured the orbital period of the Moon and the distance between Earth and the Moon, then you could calculate

The sum of the masses of Earth and the Moon

Planets with high eccentricity may be unlikely candidates for life because

The temperature varies too much

Imagine that you observe a star/planet system, edge-on. When the planet is moving away from Earth, in which direction is the star moving?

toward Earth

The diffraction limit of a 4-m telescope is _________ than that of a 2-m telescope.

two times smaller

A sidereal day is the time

required for Earth to rotate once on its axis relative to the distant stars

The moon:

rotates on its axis with the same period as its revolution about the Earth

The magnification of a telescope depends on the focal length of the telescope and

the focal length of the eyepiece

If Erath had half of its current radius, how would the strength of lunar tides change

the highs would be lower and the lows would be higher

After greatest wester elongation, before superior conjunction

Waxing gibbous Venus

Polaris, the North Star, is unique because:

it is the only star in the sky that doesn't move throughout the night.

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

to get closer to the stars

The distance between the foci when the eccentricity equals zero is

zero

If you observe the Moon rising in the east as the Sun is overhead, then you know that the phase of the Moon must be

First quarter

If we see a first quarter moon today, what will people on the other side of Erath see later today

First quarter moon

Light has aspects of

both a particle and a wave

Imagine two objects moving away from you. Object A is faster than object B. You will observe that the light

both objects are redshifted

THe connection between gravity and orbits enables astronomers to measure the ______________ of stars and planets

masses

If an object crosses from farther to closer than the Roche limit it,

may be torn apart

As a blackbody becomes hotter, it also becomes __________ and __________.

more luminous; bluer

If you push an object at its center of mass, it

moves away from you

An object that is redshifted is

moving away from us

You are standing at one of the following latitudes on the Earth's surface. At which latitude does the Sun have the highest altitude on June 21, the summer solstice in the Northern hemisphere.

+23.5 (Tropic of Cancer)

During a certain comet's orbit around the Sun, its closest distance to the Sun is 0.6 AU, and its farthest distance from the Sun is 35 AU. At what distance will the comet's orbital velocity be the largest? 1. 1.2AU 2. The comet's velocity is constant no matter what its distance is 3. 17.8 AU 4. .6 AU 5. 35 AU

.6 AU

The eccentricity of the majority of the planetary orbits in our Solar System is approximately

0

The angular resolution of a ground-based telescope (without adaptive optics) is typically

1 arcsecond (arcsec)

About how long does it take Earth to go around its axis once?

1 day

One astronomical unit (AU) is about 149,600,000 km. This distance is equal to _____ meters.

1.496 X 10^11

Two stars are of equal luminosity. Star A is 3 times as far from you as star B. Star A appears ______ star B.

1/9 as bright as

What is the surface temperature of a star that has a peak wavelength of 290 nm?

10,000 K

Which of the following is the best location for an infrared telescope on the ground?

10,000 ft about sea level

Assume that the Sun rises at 6:00 AM. About what time does the Third Quarter Moon rise?

12:00 midnight

The Voyager 1 spacecraft is currently 18 billion km from Earth and heading out of our Solar System. How long does it take radio messages from Voyager 1 to reach us?

17 hours

If you discovered a planet orbiting another star, and the planet had an orbital period of 2 years and a semimajor axis of 2 AU, what would be the mass of its parent star? You can assume the planet's mass is much less than the star's mass.

2.0 MSun

About how long does it take the Moon to orbit Eath

29 days

Suppose Betelgeuse, the bright star in the shoulder of Orion, rises above the eastern horizon at 3:00 A.M. on a particular night. Then five nights later it will rise at _____ A.M..

2:40 AM

Assume that a planet just like Earth orbits the bright star named Sirius. If this Earth-like planet orbits with a semimajor axis of 1 AU and an orbital period of 7 months, what is the mass of Sirius?

3 MSunn

The number 384,000,000 can also be written in scientific notation

3.84 X 10^8

In 2008, the Cassini spacecraft made a flyby of Enceladus, one of the icy moons of Saturn. If the spacecraft's high-resolution camera had an angular resolution of 3 arcsec and it flew at an altitude of 23 km above Enceladus's surface, how large an object could be resolved on the surface?

30 cm

The Sun and the Moon have an angular diameter of about

30' (30 arcminutes)

The speed of light in a vacuum is approximately

300,000 km/s

About how long does it take Earth to orbit the Sun

365 days

What wavelengths of light can the human eye see

380 nm to 750 nm

If the Moon were 2 times closer to the Earth than it is now, the tides would be _________ times stronger

4

The light-gathering power of a 4-meter telescope is _____________ than that of a 2-meter telescope

4 times larger

If the Moon were 2 times closer to Earth than it is now, the gravitational force between Earth and the Moon would be

4 times stronger

Light with a wavelength of 600 nm has a frequency of

5 x 10^14 Hz

Assume the Sun sets at 6:00pm. About what time does the New Moon set

6:00 PM

If you find that the Hα line in a star's spectrum occurs at a wavelength of 656.45 nm, what is the star's radial velocity? Note that the rest wavelength of this line is 656.30 nm.

70 km/s away from you

A brick pizza oven is emitting blackbody radiation that peaks at 3840 nm. How hot is the oven?

755K

If an event were to take place on the Sun, how long would it take for the light it generates to reach us?

8 minutes

A theoretical model is

A detailed description in terms of known physical laws or theories

A spaceship is traveling toward Earth while giving off a constant radio signal with a wavelength of 1 meter (m). What will the signal look like to people on Earth?

A signal with a wavelength less than 1 m

Copernicus's heliocentric model provided 1. A simpler explanation of retrograde motion 2. a way to estimate the planet-Sun distances in terms of the Earth-Sun distance 3. a way to estimate how long it took each planet to orbit the sun

All answers are correct

A theory is: 1. A hypothesis that has withstood many attempts to falsify it 2. Tied to known physical laws 3. Able to make testable predictions

All options are correct

Just after sunset, a star appears near the western horizon. Where will it appear to be after 6 hours

Below the western horizon

For a system in which a planet orbits a star, the center of mass is located

Along the line between the planet and the star, closer to the star

For a pair of objects, the center of mass is located

Along the line between the two objects, closer to the more massive object

Why is an iron atom a different element from a sodium atom?

An iron atom has more protons in its nucleus than a sodium atom has

The term satellite in astronomy means

Any low-mass object that is orbiting a more massive object

IF the Moon was New last Sunday, what phase will it be this Sunday

At or very near First Quarter

Where on the Earth can you see the north celestial pole on the horizon?

At the equator

Where on Earth can you see the north celestial pole at the zenith?

At the north pole

A spaceship approaches Earth at 0.9 times the speed of light (0.9c) and shines a powerful searchlight onto Earth. How fast will the photons from this searchlight be moving when they hit Earth?

At the speed of light, c

In the heliocentric model of the Solar System, which planets exhibit retrograde motion?

Both superior and inferior planets

The horizon is defined

By the idrection perpendicular to a line to the zenith

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

If you are standing in a fixed location, you may notice that the pitch of a passing train's whistle changes. What produces this effect?

Doppler effect

At the center of the geocentric model of the Solar System is the

Earth

What causes the angle of the Sun to change over the year?

Earth's North Pole always points in the same direction in space. Sometimes this is toward the SUn, and sometimes its away from the Sun

Ultraviolet radiation with wavelengths shorter than about 200 nm are hard to observe primarily because

Earth's atmosphere easily absorbs it

There is an angle between the ecliptic and the celestial equator because

Earth's axis is tilted with respect to its orbit

A lunar eclipse occurs when _____________ shadow falls on ______________

Earth's, the Moon

The Moon and a particular star appear in the same place in the sky one night. Where will the Moon be located one week from now?

East of the star

What is the parth of the Sun across the sky called?

Ecliptic

If you observe the Moon rising in the east as the Sun is setting in the west, then you know that the phase of the Moon must be

FUll

Suppose tonight is new moon. You are standing on the Moon, facing the Earth. What phase Earth do you see?

Full Earth

Superior conjunction

Full Venus

Best time to observe an inferior planet in the evening

Greatest easter elongation

How did Ptolemy "fix" the geocentric system?

He introduced epicycles

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

What does it mean for a planet to be at opposition?

It is closest to Earth in its orbit

Assume that at sunset today, Jupiter appears to be 20 degrees away from the Sun. If the sidereal period of Jupiter is 12 years, when will it next appear in this same position relative to the Sun?

In 12 years

Suppose you are suddenly transported to a planet that had 1/4 the radius of Earth but the same mass as Earth. Your weight would _________ by a factor of _________.

Increase; 16

_________ 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

What does it mean for a star to be circumpolar?

It never sets below the horizon

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

Its acceleration is zero

Suppose you read in the newspaper that a new planet has been found. Its average speed in orbit is 33 km/s. When it is closest to its star it moves at 31 km/s, and when it is farthest from its star it moves at 35 km/s. This story is in error because

Kepler's seconds law says the planet must move fastest when it is closest, not when it is farthest away

Which of the following are the inferior planets?

Mercury and Venus

Which planet is the only one that could be in opposition (Mercury, Venus, Earth, Mars)

Mars

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

Mars has a polar ice cap similar to Earth

Which of the following are superior planets

Mars, Jupiter, Saturn

Which planet has a synodic period relative to Earth that is longer than its sidereal period?

Mercury

If you have two moons that have the same radius, but Moon A is denser and has 2 times the mass of Moon B, how do their escape velocities compare?

Moon A has an escape velocity that is 1.4 times larger than Moon B

When using the scientific method, a hypothesis that would explain a particular observation

Must be able to be tested

As seen from the Moon, how often does the Earth set

Never

INferior Conjunction

New Venus

In science an idea that cannot be tested is

Not a scientific idea

A star appears circumpolar at a location at +30° latitude. How will it appear from -30° latitude?

Not visible at all

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

Occam's razor

Kepler's third law for our Solar System can be expressed mathematically as

P^2 = A^3

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

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

Kepler's second law says that

Planets move fastest when they are closet to the Sun

Who of the following was not a proponent of the heliocentric model of the solar system

Ptolemy

Greatest easter elongation

Quarter Venus

The Doppler shift can be used to determine the _________ of an object.

Radial velocity

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

The speed of light was first determined by which scientist?

Romer

Star A and star B appear equally bright in the sky. Star A is twice as far away from Earth as star B. How do the luminosities of stars A and B compare?

Star A is 4 times as luminous as star B

An alignment when a planet appears on the opposite side of the Sun from Earth

Superior conjunction

The time it takes for a planet to come back to the same position relative to the Sun is called its _________ period.

Synodic

Which term describes how long it takes the Moon to make a full cycle of phases?

Synodic month

In order to account for retrograde motion, Ptolemy had to resort to what embellishment to his geocentric model for the solar system?

That planets would travel on smaller circles that were superimposed onto their larger, circular orbits around the Earth

When a boat moves through the water, the waves in front of the boat bunch up, while the waves behind the boat spread out. This is an example of

The Doppler effect

Which of the following are in order from smallest to largest?

The Milk Way Galaxy, The Local group, the virgo supercluster

We always see the same side of the Moon because

The Moon rotates on its axis once for each revolution around Earth

Tides on Earth are primarily due to

The Moon's gravitational pull on the Earth

Why do solar eclipses seem much rarer than lunar eclipses

The Moon's shadow is much smaller than the Earth's , so each solar eclipse is only visible within a small area

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

The comet's speed is greatest when its nearest the Sun

Because of _______________, we can conclude that gravity works the same way on Earth as it does on Mars

The cosmological principle

If the wavelength of a beam of light were to double, how would that affect its frequency?

The frequency would be two times lower

If the Moon had twice the mass that it does, how would the strength of the lunar tides change?

The high tides would be higher, and the low tides would be lower.

Which is not true on the vernal and autumnal equinoxes?

The motion of the stars in the sky is different than on other days/

Astronomers argued that the heliocentric model of the Solar System was simpler than the geocentric model, based on

The observed retrograde motions of the planets

Day and night are caused by

The rotation of Earth on its axis

At sunrise, the Moon is about 45° above the eastern horizon. What phase is it in?

Waning crescent

After greatest eastern elongation, before inferior conjunction

Waning crescent Venus

What is the difference between visible light and X-rays

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

A planet appears overhead near sunrise

Western quadrature

Imagine a planet in a very eccentric elliptical orbit around a star. This planet has no moons, but it has oceans. This planet's orbit not tidally locked. Are there tides?

Yes, because the strength of the tidal force will change with the distance from the star

IF Earth did not have a moon, would we still have tides

Yes, but our tides would be only about half as strong since the Sun's tidal force is about half of the Moon's

When an electron moves from a higher energy level in an atom to a lower energy level,

a photon is emitted

AN atmospheric window is

a region of the electromagnet spectrum that can reach the ground

Which of these stars would have the biggest redshift

a star moving at high speed away from you

A centripetal force is

any force that points toward center of a circular path

Constellations are groups of stars that

are close to each other in Earth's sky

The temperature of an object has a very specific meaning as it relates to the object's atoms. A high temperature means that the atoms

are moving very fast

A star that is noticeably redder in color than another is likely

at a lower temperature than the other

The angular resolution of a ground-based telescope is usually determined by

atmospheric seeing

Imagine that you observe a star/planet system, edge-on. When the planet is moving away from Earth, the light from the star is

blueshifted

An object in a(n) __________ orbit in the Solar System will remain in its orbit forever. An object in a(n) __________ orbit will escape from the Solar System.

bound; unbound

What does amplitude reveal about light

brightness

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

c = yf

A full moon

can never rise at midnight

Saying that something is quantized means that it

can only have discrete quantities

The Sun, Moon, and stars

change their relative positions over time

An inferior planet is one that is

closer to the Sun than Earth is

Looking down on Earth from above the North Pole, the Moon orbits Earth

counterclockwise

Suppose you are suddenly transported to a planet with 1/4 the mass of Earth but the same radius as Earth. Your weight would _________ by a factor of _________.

decrease 4

If we wanted to increase the Hubble Space Telescope's altitude above Earth and keep it in a stable orbit, we also would need to

decrease its orbital speed

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

decreases, decreases

A_____________ becomes a ______________when repeated testing of its predictions does not disprove it

hypothesis; theory

If the distance between Earth and the Sun were cut in half, the gravitational force between these two objects would

increase by 4

Which of these types of electromagnetic radiation has the longest wavelength

infrared

The phase of the Moon at a solar eclipse

is always new

If you went to Mars, your weight would be

lower because Mars has lower mass and a smaller radius that together produce a lower gravitational force

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

mass

You observe the spectrum of two stars. Star A has an emission line from a known element at 600 nm. Star B has emission lines from the same atom, but the emission line is occurring at 650 nm. One possible explanation for this observation is: that star A is

moving toward us faster than star B

During an annular solar eclipse, the Moon must be

near apogee, because its angular size is smaller

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

nothing

The radial velocity of a star or other object is measured by

observing the Doppler shift of spectral lines in the light from the object

As two objects orbit one another, they are always

on opposite sides of the center of mass, traveling in opposite directions in space

You see the first quarter Moon on the meridian. Where is the sun?

on the western horizon?

A planet appears overhead at midnight

opposition

Keplers third law is a relationship between an orbiting object's

period and semimajor axis

Einstein showed that the _________ could be explained if photons carried quantized amounts of energy.

photoelectric effect

In Newton's universal law of gravitation, the force is

proportional to both masses

A scientific theory can be shown to be wrong if

scientists gather new data that contradict its predictions

The average distance between a planet and the Sun is given by the _________ of its elliptical orbit.

semimajor axis

The amount of time a planet takes to orbit the Sun is called its _______________ period

sidereal

Galileo observed that Jupiter has moons. From this information, you may conclude that;

some things do not orbit Earth

According to kepler's laws, a comet with a highly eccentric orbit will

spend most of its time far from the sun

You are shopping for telescopes online. You find two in your price range. One of these has an aperture of 20 cm, and the other has an aperture of 30 cm. If aperture size is the only difference, which should you choose, and why?

the 30 cm, because the light-gathering power will be better

The Local Group is the environment around

the Milky Way that contains a few dozen galaxies

Spring tides occur only when

the Moon's phase is new or full

The aperture of a telescope is which of the following

the diameter of the primary lens/mirror

the distance used in Newton's law of gravitation is

the distance between the centers of the object

Where on Earth can you stand and, over the course of a year, see the entire sky?

the equator

In a star with a temperature of 10,000 K, the transition from level 3 to level 1 of hydrogen produces photons with a wavelength of 102.5 nm. In a star three times as hot as the first, this transition produces photons with

the same wavelength

Compare to your mass on Earth, on the Moon your mass would be

the same, mass doesn't change

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

If two objects are tidally locked to each other

the tides always stay on the same place on each object AND the objects always remain in the same place in each other's sky.

How does the resolution of a telescope depend on its focal length?

there is no relation between resolution and focal length

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

they are in constant free fall around Earth

Why don't we see cars as bluer when they approach and redder when they recede?

they are too slow

Saturn's rings do not clump together to form a moon because

they lie within Saturn's Roche limit

You see the Moon on the meridian at sunrise. The phase of the Moon is

third quarter

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

visible and radio

The color of visible light id determined by its

wavelength

Which phase comes immediately before first quarter?

waxing crescent

The "second" high tide in a 24-hour day is caused by

weaker gravity pulling on Earth on the side opposite the Moon

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

weight

When a planet exhibits retrograde motion it moves in which direction relative to the stars

westward

Solve the following equation for x in terms of y: y=3x

x=y/3