Astronomy questions
In the absence of a greenhouse effect, what would happen to Earth's oceans?
They would freeze over.
When we determine the angular resolution of a single dish telescope using the formulae θ=λ/Dθ=λ/D, the variable D stands for
diameter of the telescopes
Doppler shifts can be measured when
diffuse, hot gas is moving away from the observer
Which of the following is a bound orbit?
elliptical b. hyperbolic c. circular d. both A and C
A hot, rarified gas will produce what kind of spectrum?
emission line
Prior to colliding with the Earth, most meteorites are thought to originate from the ________.
fragments of asteroids located between Mars and Jupiter
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
Which scientific theory best accounts for the Solar System's formation?
gravitational contraction of the primordial solar nebula
When sunlight is passed through a spectroscope an absorption spectrum is observed because the Sun
has a hot interior that shines through cooler low density gas
when sunlight is passed through a spectroscope an absorption spectrum is observed because the Sun
has a hot interior that shines through cooler low density gas
An accelerating body should/could
have a changing direction of motion have a changing velocity move in a curved lines Correct! All of the above
The advantage of Hubble telescope compared to the ground-based optical telescopes is
high resolution (possibility of resolving at tiny angular scales)
The relationship between frequency and wavelength [frequency x wavelength = c] common to all electromagnetic waves tells us that ________.
higher frequencies correspond to shorter wavelengths
Why it is unlikely to form a gas giant in the near orbits of a star in a stellar system?
The surface gases of the gas giant will be dragged into the star due to gravity
Spectral lines are produced by the ________.
transitions or jumps of electrons inside atoms
In Newton's law of gravity F=−GMmR2F=−GMmR2 , the constant G is
universal constant independent of other parameters;
The part of the human eye that acts as the detector is the
retina
Which of the following is the most appropriate reason that we do not observe a gas giant orbiting around a terrestrial planet as a satellite?
the gas giant is much heavier than the terrestrial object
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 does not fall onto Sun's surface because
it has large speed
How does the light-gathering power of a 4 m telescope compare to that of 2 m telescope
it is 4 times as much
What makes carbon dioxide a highly effective greenhouse gas?
It easily absorbs infrared radiation
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.
Which of these objects would exhibit an absorption spectrum?
a thin, cool gas cloud that lies in front of a hotter blackbody
How often do leap years occur?
almost every 4 years
Which of the following choices is produced when white light is shined through a cool gas:
an absorption spectrum
If you observe an isolated hot cloud of gas, you will see
an emission spectrum.
Light has aspects of
both a particle and a wave
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 primary difference between a moon and a planet is that
moons orbit planets, whereas planets orbit stars.
The diameter of the Moon is
more than half the distance across the continental United States.
Why was adaptive optics developed?
to compensate for image distortion by the Earth atmosphere
Which of the observing tasks below may telescopes regularly provide for astronomers?
-----all of the other three spectroscopy measuring the intensity imaging
If an object is moving in a circular orbit at a constant speed, which of the following is false?
. Its acceleration is not zero. b. Its acceleration is zero. c. Its velocity is not zero. d. There is an unbalanced force acting on it.
During a certain comet's orbit around the Sun, its closest distance to the Sun is 0.6 Astronomical Unit (AU), and its farthest distance from the Sun is 35 AU. At what distance will the comet's orbital velocity be the largest?
0.6 Astronomical Unit (AU)
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
The Earth's mass is 80 times larger than the Moon's mass. What is the ratio of the gravitational force the Earth exerts on the Moon to the gravitational force the Moon exerts on the Earth?
1 to 1
Two stars are of equal luminosity. Star A is 10 times as far from you as star B. Star A appears _______________ star B
1/100 as bright as
Two stars are of equal luminosity. Star A is 4 times as far from you as star B. Star A appears _______________ star B
1/16 as bright as
The nucleus of the typical comet is approximately _________ in size.
10 km
The radius of Neptune is about 4 times that of the Earth and its mass is about 17 times of the Earth. Estimate the acceleration due to the gravity of Neptune's surface. Given: acceleration due to gravity on Earth's surface g = 9.81 m s^-2
10.4m s^-2
One of the nearest stars is Alpha Centauri, light to travel from Alpha Centauri to us?
4.4 years
1. Suppose the radius of Jupyter is about 13.2 times that of the Earth and its mass is about 318 times of the Earth. Estimate the acceleration due to the gravity of the planet's surface. Given: acceleration due to gravity on Earth's surface g = 9.81 m s^-2
17.90 m s^-2
The transit method is one of the methods that allow us to identify the size of the exoplanet in observations due to the drop of the intensity. Suppose we observe a star using this method and detect two exoplanets with two drops of intensity curve, which is shown in the figure below. For convenience, we overlap the two curves. What is the ratio of the radius between two planets?
1:2
The transit method is one of the methods that allow us to identify the size of the exoplanet in observations due to the drop of the intensity. Suppose we observe a star using this method and detect two exoplanets with two drops of intensity curve, which is shown in the figure below. For convenience, we overlap the two curves. What is the ratio of the radius between two planets?
1:4
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
2 km/s
If the temperature of an object were halved, the wavelength where it emits the most amount of radiation will be
2 times longer
if the temperature of an object were halved, the wavelength where it emits the most amount of radiation will be
2 times longer
if the temperature of an object were halved, the wavelengthwhere it emits the most amount of radiation will be
2 times longer
Suppose we have a protoplanetary system that contains a Sun-Earth system. The system's star is twice as heavy as the Sun, while the mass of the planet is 3 times as heavy as Earth. The radius of the planet is the same as the Earth. The separation between the star and the planet in this protoplanetary system is 5 times of that between Sun and Earth. If the instructor's weight is 700 N (Neuton) on the earth, what is his weight on the planet? Useful formulate F=−GM1M2R2F=−GM1M2R2 In the case when M1=EarthM1=Earth , the gravitational acceleration g=GM1R2≈10ms−2g=GM1R2≈10ms−2 .
2100 N
If a tenth planet were to be discovered with a period of 125 years, what would be the radius of its circular orbit?
25 AU
An object was found in a Solar system with semimajor axis approximately 40 AU. What is its rotational period around the Sun?It is approximately:
250 years
The speed of light is approximately
300,000 km/s.
If a new planet is found in the solar system with an orbit distance of 50AU, what is its period?
350 years
After the Sun, the next nearest star to us is approximately _________ away.
4 light-years
Suppose a group of astronomers discovered a new star that is emitting mostly green light at around 550 nm. What of the following temperature estimation could be possible for this star?
4996 C
Suppose a group of astronomers discovered a new star that is emitting mostly blue light at around 400 nm. What of the following temperature estimation could be possible for this star? (b=2.898×106nm⋅K2.898×106nm⋅K )
6972 C
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 * 101 1 m, and light from the Sun takes approximately _________ to reach Earth.
8 minutes
An asteroid is orbiting the Sun at a distance of 4 Astronomical Units. Its period is
8 years
By what factor does the total energy emitted per unit time at all wavelength from a blackbody increase if its temperature increases by a factor of 3
81
Two stars are of equal radius. Star A's effective temperature is 3 times hotter than star B. What is the ratio of luminosity between star A and star B?
81:1
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 Hubble telescope to the energy collected by the human eye is
90, 000
Venus's extremely high surface temperature (900° F) is accounted for by what process?
A runaway greenhouse effect is maintained by its carbon dioxide atmosphere.
Which giant planets have rings?
All of them
Is light a particle or a wave?
Both a particle and a wave.
Why do the giant planets have the largest share of moons in the solar system?
Being the most massive planets in the solar system, they were able to gather more material to form moons than the terrestrial planets
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.
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.
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.
_________ 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
Suppose you read online that "experts have discovered a new planet with a distance from the Sun of 2AU and a period of 3 years". This discovery is not physically plausible because:
It violates the Kepler's 3rd law.
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.
What is the reason Mercury has so little gas in its atmosphere?
Its mass is small It has a high temperature ------ all of the above Its escape velocity is low
Who discovered Neptune?
Johann Galle
Which planet has the greatest surface gravity?
Jupiter
We all know that some places on the Earth have more frequent earthquakes than other places, e.g. Japan, California, Chile. Why don't we usually experience earthquakes in Madison?
Madison is not located at the plate boundaries
Most asteroids are located between the orbits of
Mars and Jupiter
Mars has a similar size and mass as Earth; so why do we think that the planet lacks a comparable magnetic field?
Mars' metallic core has cool down
Which statement below does NOT describe one of the advantages of reflecting telescopes over refracting telescopes?
Mirrors reflect only certain colors of light to form an image.
_________ is the idea that the simplest explanation for a phenomenon is usually the correct one.
Occam's razor
Kepler's third law of planetary motion relates the period P (in years) to the length of the semimajor axis a in which way?
P^2=a^3
Who of the following was not a proponent of the heliocentric model of the solar system?
Ptolemy
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.
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 the distance between 2 astronomical bodies is tripled, what effect does this have on the force of gravity between the 2 bodies?
The force decreases by a factor of 9
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.
The microlensing method is one of the methods that allow us to identify the exoplanet in observations. The principle behind this method is:
The light of the background star becomes temporary brighter due to the gravity of the exoplanet
The mass of a 10 kg rock would be _______ if it were located in deep space away from any star:
The same
What is the difference between visible light and X-rays?
Wavelength; X-rays have a shorter wavelength than visible light.
The below shows two spectra observed by a group of astronomers. What are these spectra?
Top: Absorption, Below: Emission
On which of these planets is the atmospheric greenhouse effect strongest?
Venus
Venus is hot and Mars is cold primarily because
Venus has a much thicker atmosphere
The terrestrial planets, ranked in order of decreasing atmospheric density, are
Venus, Earth, Mars, Mercury
Which type of electromagnetic radiation must be observed using a space-based telescope?
X-rays
Which of the following photons carries the smallest amount of energy?
a microwave photon, whose wavelength is 10−210−2 m
The time it takes light to cross Neptune's orbit is closest to which of the following?
a night's sleep
Magnetosphere refers to
a region of magnetic field around Earth
Which of these stars would have the biggest redshift?
a star moving at high speed away from you
Which of the following is false?
a. A scientific theory is an undisputed fact. b. If continual testing of a hypothesis shows it to be valid, it may become an accepted theory. c. A hypothesis must always have one or more testable predictions. d. A scientific theory may eventually be proven wrong when scientists acquire new data.
Which of the following is false?
a. Everyone on Earth observes the same phase of the Moon on a given night. b. In some phases, the Moon can be observed during the day. c. The observed phase of the Moon changes over the course of one night. d. A full Moon can be seen on the eastern horizon at sunset.
A hypothesis is an idea that is
a. falsifiable with current technology. b. potentially falsifiable with future technology. c. not falsifiable. d. both a and b
Earth is located approximately
about halfway out from the center of the Milky Way.
A high mountaintop such as Mauna Kea in Hawaii is a good site for an infrared observatory because it is
above most of the moisture in the Earth's atmosphere
When a cool, rarified gas is placed between a hot, glowing solid and the observer, what kind of spectrum is seen?
absorption line
What is the principal advantage that results from placing astronomical telescopes in orbit around the Earth?
access to the entire electromagnetic spectrum
The ________ of a telescope is a measure of its ability to show fine detail and varies inversely with the diameter of the objective lens or mirror.
angular resolution
One of the central assumptions in astronomy is that the physical laws of nature
are the same everywhere in the universe.
The limit of the resolution of the biggest ground based telescope is due to
atmospheric distortion of light propagation
Consider a star that is significantly more massive and hotter than the Sun. For such a star, the habitable zone would
be located outside 1AU
Why is it relatively difficult to observe Mercury from Earth?
because it is a very small stellar object that always is too close to the Sun in observations
Our universe is approximately 13.7 _________ years old.
billion
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
________ was the first person to introduce a mathematical heliocentric model of the Solar System from which accurate predictions could be made of planets' positions.
c. Johannes Kepler
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 type of spectrum given off by a hot, glowing solid (e.g., a lamp filament) is a(n) ________ spectrum.
continuous
The majority of the mass in our universe is made up of
dark matter.
What is the main reason that Earth's interior is liquid today?
decay of radioactive elements
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.
The early universe was composed mainly of which two elements?
hydrogen and helium
Kepler's second law states that a planet moves fastest when it
is closest to the Sun.
Much of the mass of our Galaxy appears to be in the form of "dark matter", which can be detected at present because
its gravitational pull affects orbital motion in the Galaxy
The light from an object gets redshifted due to
its motion away from us
The majority of the energy in our universe is
made up of dark energy that permeates space.
How many forces need to be applied to a body in space to keep it moving with a constant velocity?
none;
If the Sun is located at one focus of Earth's elliptical orbit, what is at the other focus?
nothing
A body moves through space with a certain speed. How many forces are needed to make this object move in a circle?
only one, toward the center of the circle;
The Moon probably formed
out of a collision between Earth and a Mars-sized object.
The time it takes a planet to complete one full orbital revolution is commonly known as its
period
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
The Moon undergoes synchronous rotation, and as a consequence the a. rotational period of the Moon equals the orbital period of the Moon around Earth
rotational period of the Moon equals the orbital period of the Moon around Earth
The Moon undergoes synchronous rotation, and as a consequence the
rotational period of the Moon equals the orbital period of the Moon around Earth
By measuring the motion of the small moon around Saturn we can find the approximate mass of
saturn
Which of the Kepler's laws explains why comets on high eccentricity orbits spend most of their orbital period far from the Sun
second law
When we determine the angular resolution of an interferometric array of radio telescopes using the formulae θ=λ/Dθ=λ/D , the variable D stands for
separation between the telescopes
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
The Local Group is the environment around
the Milky Way that contains a few thousand 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
A natural greenhouse effect occurs on Earth because ________.
the atmosphere allows shorter-wave sunlight to enter, but traps longer-wave infrared energy re-radiated by the surface
Tidal forces are caused by
the difference between the strength of the gravitational pull of the Moon and Sun on either side of Earth.
Visible light makes up a small portion of the much larger family of radiant energy called ________.
the electromagnetic spectrum
Galileo's observations of the sky with his telescope included
the fact that Venus showed phases, similar to those of the Moon;
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
Gravity is
the strongest force. b. a fundamental force. c. a mutually attractive force. d. a mutually repulsive force. e. both B and C
A black car left in the sunlight becomes hotter than a white car left in the sunlight under the same conditions because
the white care reflects more sunlight than the black car
Astronauts orbiting Earth in the space shuttle experience so-called weightlessness in space because
they are in constant free fall around Earth.
If a very large (massive) anvil collides with a very small child which object is subject to a greater force?
they feel the same force
A theory is
tied to known physical laws. b. able to make testable predictions. c. a hypothesis that has withstood many attempts to falsify it. d. all of the above
A big problem for infrared observations is
water vapor
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)