Astronomy Ch. 5 – 10

Flashcard maker : Marie Florence
Bohr Model
A model of an atom, proposed by Niels Bohr, in which a small positively charged nucleus is surrounded by orbiting electrons, similiar to a miniature solar system
Heisenberg Uncertainty Principle
The physical limitation that the product of the position and the momentum of a particle cannot be smaller than a well-defined value, Planck’s constant (h).
Emission
The production of a photon when an atom decays to a lower energy state
Absorption
The process by which an atom captures energy from a passing photon
Doppler Effect
The change in a wavelength of sound or light that is due to the relative motion of the source toward or away from the observer
As a blackbody becomes hotter, it also becomes_____ and ______.
More luminous; bluer
Which of the following factors does NOT directly influence the temperature of a planet?
The size of the planet
Factors that DO influence:
Distance from the planet to the sun
The albedo (reflective properties) of the planet
The luminosity of the Sun
Two stars are of equal luminosity. One is twice as far from the other, the closer star appears:
Four times brighter
(Farther away, 1 / d^2 as bright)
(T/F) Blue light has more energy than red light.
True. Blue light has a higher frequency, therefore has more energy.
(T/F) Cooler objects emit more of their total light at shorter wavelengths than hotter objects
False (backwards!)
Beam 1 has half the wavelength of beam 2. How do their frequencies compare?
Beam 1 has two times the frequency of beam 2
Momentum is a product of:
mass & velocity
At what wavelength does your body radiate the most energy?
10^-5 meter / microwave
What is the surface temperature of a star that has a peak wavelength of 290 nm?
10,000 K
If photons of blue light have more energy than photons of red light, how can a beam of red light carry as much energy as a beam of blue light?
The red beam must contain more photons to carry the same total energy
Refracting Telescope
Glass lens is curved, light at the outer edges of the lens is refracted more than light near its center. Concentrates the light rays entering the telescope, bringing them into a sharp focus. Lets in light and magnifies image.
Reflecting Telescope
Light from an object enters the telescope tube and is reflected off a curved mirror at the end of the tube.
All large astronomical telescopes are reflectors because:
Chromatic aberration is minimized, they are not as heavy as refracting telescopes, they can be shorter than refracting telescopes
One telescope has an aperture of 20 cm and one has an aperture of 30 cm, which should you choose and why?
The 30cm because the light-gathering power will be better
The kepler mission telescope observes primarily in visible light. this telescope is located in space because
It is above atmospheric distortion
Which of the following can be observed from Earth’s surface?
Radio waves
Arpeture
The clear diameter of a telescope’s objective lens or primary mirror
Chromatic Abberation
A detrimental property of a lens in which rays of different wavelengths are brought to different focal distances from the lens
Diffraction
The spreading of a wave after it passes through an opening or beyond the edge of an object
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
Spacecraft are the most effective way to study planets in our Solar System because:
They can collect more information than is available just from images
(T/F) Chromatic aberration is a problem that limits the image quality of reflecting telescopes
False
Chromatic aberration is associated with refracting telescopes
(T/F) Radio telescopes are often used in interferometric arrays to increase light-gathering power
True
One of the reasons why the hubble space telescope has better spatial resolution than a 4-m ground based telescope is that it has large mirror
False
Also: not the largest telescope built & there is no blurring due to the atmosphere
The light-gathering power of a 4-meter telescope is _______than that of a 2-meter telescope.
4 times larger
The part of the human eye that acts as the detector is the
Retina
Astronomers put telescopes in space to
Avoid atmospheric effects
The angular resolution of a ground-based telescope is usually set by:
Atmospheric seeing
Which of the following causes the biggest problem in detecting infrared photons from an astronomical object?
Water Vapor
Robotic landers are more common than simple-return spacecraft because:
Carrying enough fuel to get back to Earth makes sample return expensive
Place the following events in the order they occur during the formation of planetary system:
Gravity collapses a cloud of interstellar gas
A rotating disk forms
Dust grains stick together by static electricity
Small bodies collide to form larger bodies
Primary atmosphere form
A stellar wind \”turns on\” and sweeps away gas and dust
Primary atmosphere is lost
Secondary atmospheres form
If the radius of an object’s orbit is halved, what must happen to the speed so that angular momentum is conserved?
It must be doubled
Accretion Disk
A flat, rotating disk of gas and dust surrounding an object, such as a young stellar object, a forming planet, a collapsed star in a binary system, or a black hole
Unlike the giant planets, the terrestrial planets formed when:
The inner Solar System was hotter than the outer Solar System

-The planets closer to the sun were hotter and as a consequence captured less gas as the Solar System was forming.

Planetary systems in the Milky Way Galaxy are probably:
Common (many stars have planets)

-Planet formations and star formation seem to go hand in hand

Extrasolar planets have been detected by the:
– Gravitational lensing method/Microlensing
-Transit method
-Direct imaging method
-Spectroscopic radial velocity method
The terrestrial planets and the giant planets have different composition because:
The terrestrial planets are closer to the sun.

– The hotter planets in the inner Solar System collected less gas than cooler, outer planets.

The spectroscopic racial velocity method preferentially detects…
Large planets close to the central star
Spectrograph
A device that spreads out the light from an object into its component wavelengths (a.k.a spectrometer)
The concept of disk instability was developed to solve the problem that:
The early solar nebula likely dispersed too soon to form Jupiter.

-The disk instability theory proposes that a disk could break up into large planet-like components which happens very rapidly, as opposed to the slow process of accretion

When extrasolar planets were first discovered, they were surprising, and astronomers had to:
Modify the theories of the formation of stellar systems.
(T/F) A cloud of interstellar gas is held together by gravity
True.

-Aside form chemical bonds that hold together rock or chunks of metal, almost everything in the universe that is held together is done so by gravity.

Is a molecular cloud held together by gravity?
True.

-Any cloud of gas will be bound by gravity

(T/F) Gravity and angular momentum are both important in the formation of the planetary system.
True.

-Gravity is what causes the cloud to collapse and what allows larger planetariums to grow. Angular momentum spins up the protoplanetary disk as it contracts which increases the rate of collisions of small particles, allowing them to grow into planetesimals.

(T/F) Volatile materials are solid only at low temperatures.
True.

-This is why the inner planets collected less gas in their atmosphere than the outer planets.

-Volatile materials turn into liquids and vapors at moderate to high temperatures.

Volatile material
Sometimes called ice. Material that remains gaseous at moderate temperature.
(T/F) The solar system formed from a giant cloud of dust and gas that collapsed under gravity.
True.

– All starts and most planetary systems are made this way. The same can be said for all stars, too.

(T/F) Microlensing similar to the transit method in that both require the planet to pass in front of a bright object.
True.

-The differnce between microlensing and transits is that in the latter the bright obejct is dimmed; while in the former the object becomes brighter

Since angular momentum is conserved, an ice-skater who throws her arms out will do what?
Rotate more slowly. This is an expression of the conversation law of angular momentum
Clumps grow into planetesimals by:
Colliding with other clumps.

-This series of colliding with other clumps helped form the planets we see today. In the early solar system, collisions between particles and clumps cause them to stick together and grow in size.

If the radius of an object’s orbit is halved, what must happen to the speed so that the angular momentum is conserved?
It must be doubled. Since angular momentum L=mvr, we see that if the distance r is halved, the speed v must be doubled
The amount of angular momentum in an object depends on what?
Its radius, mass, and rotation speed
The spectroscopic radial velocity method of planet discovery measures a motion that is most like the motion of what?
An ice-skater spinning his partner. Spectroscopic radial-velocity measurements pick up the Doppler shift of a star being tugged by its orbiting planet, much like a very small Chihuahua tugs on its owner when being walked
The planets in the inner part of the Solar System are made primarily of refractory materials; the planets in the outer Solar System are made primarily of volatiles. The reason for the difference is that:
There were no volatiles in the inner part of the accretion disk.

-Volatiles are easily evaporated or broke up with heat, and it was too hot in the inner solar system for these compounds to be present

Which of the following planets still has its primary atmosphere?
Jupiter.

-Rememer that the \”primary\” atmosphere is the one the planet formed with; the terrestial planets all lost their soon after formation

If scientists want to find out about the composition of the early Solar system, the best object to study are:
Asteroids and comets.

-Asteroids and comets are made almost exclusively of the pristine material out of which the solar system formed

The discovery of \”hot Jupiter\” planets close to their central star led to the theoretical model of what?
Planet migration
Protoplanetary Disk
The remains of the accretion disk around a young star from which a planetary system may form
Planet Migration
The theory that a planet can move to a location away from where it formed, through gravitational interactions with other bodies or loss of orbital energy from interaction with gas in the protoplanetary disk.
______,_______, and _________ build up structures on the terrestrial planets, while in general, ________ tears them down.
Impacts, tectonism, volcanism; erosion
If crater A is inside crater B, we know that:
Crater B was formed before Crater A
Scientists learn about the interior structure of planets by using- (choose all that apply)
Observing of seismic waves
Model of Earth’s interior
Observations of magnetic fields
If a radioactive element A decays into radioactive element B with a half life of 20 seconds, then after 40 seconds:
One-quarter of element A will remain
______ are compressional, while ______ oscillate perpendicular to the line of travel.
Longitudinal and P waves; transverse and S waves
Earth’s interior is heated by:
Radioactive decay and tidal effects
Lava flows on the moon and Mercury created large, smooth plains. We don’t see similar features on Earth because:
Earth has plate tectonics and erosion that modify the surface
What is the process by which heavier molten material sank deeper into the planetary core, leaving the outer layers made of lighter material?
Differentiation
How do scientists know the history of Earth’s magnetic field?
The magnetic field freezes into rocks, and plate tectonics spreads them out
(T/F) Volcanism has been present on all terrestrial planets.
How do we infer that volcanism was a process that was present on other terrestrial worlds (mercury, mars, the moon)?
True.

-Relatively smooth expanses of crust

(T/F) Impact cratering no longer affects the terrestrial planets.
False
The geological processes that shape a planet have ceased on Earth.
False
Large worlds are geologically active longer than smaller worlds because:
They have more radioactive fuel and they lose heat at a slower rate
(T/F) Wind erosion is an important process on Venus.
True
Out of the four processes that shape the surface of the terrestrial world, the one with the most potential for catastrophic re-arrangement is:
Impact cratering

-Other processes: volcanism, tectonism, & erosion

Geologists can find the relative age of impact craters on a world because:
The ones on the top must be younger
Geologists can find the actual age of features on a world by:
Radioactive dating of rocks retrieved from the world and
Comparing cratering rates on one world to another
Impacts on the terrestrial worlds and the Moon:
Are less common than they used to be
Comparative planetology
The study of planets through comparison of their chemical and physical properties.
Earth has fewer craters than Venus. Why?
Earth’s surface experiences more erosion
Imagine that you are rock collecting in Arizona and you find rock containing shock-modified quartz. You immediately know the rock:
Formed during an impact
Scientists can learn about the interiors of terrestrial planets from:
Seismic waves
Satellite observations of gravitational fields
Physical arguments about cooling
Satellite observations of magnetic fields
Convection
The transport of thermal energy from lower (hotter) to the higher (cooler) layers of a fluid by motions within the fluid driven by variations in buoyancy.
Place in chronological order the following steps in the formation and evolution of Earth’s atmosphere:
1. Hydrogen and helium are captured from the protoplanetary disk.
2. Hydrogen and helium are lost from the atmosphere.
3. Volcanoes, comets, and asteroids increase the inventory of volatile matter.
4. Life releases CO2 from the subsurface into the atmosphere.
5. Plant life converts CO2 to oxygen.
6. Oxygen enables the growth of new life-forms.
Mercury has (essentially) no atmosphere because:
It’s small
Rank these planets where the atmospheric greenhouse effects are the strongest (to weakest):
Venus, Earth, Mars, Mercury
Earth’s atmosphere is much different in composition than Venus’s atmosphere because:
Water is a liquid on the surface of Earth
If your body were not in hydrostatic equilibrium with the air, it would:
Swell or contract until equilibrium was reached.
The difference in climate between Venus, Earth, and Mars is primarily caused by:
The thickness of their atmospheres
What does Earth’s magnetosphere do?
Shields us from the solar wind
Is essential to the formation of auroras
Extends far beyond Earth’s atmosphere
Auroras do not happen on the Moon, because the Moon:
Does not have a strong magnetic field and does not have an atmosphere
Studying climate on other planets is important to understanding climate on Earth because:
Underlying physical processes are the same on every planet
Other planets offer a range of extremes to which Earth can be compared
Comparing climates on other planets helps scientist understand which factors are important
Other planets can be used to test atmospheric models
(T/F) The current atmosphere of the terrestrial planets were formed when the planets formed
False
(T/F) Life is responsible for the presence of oxygen in Earth’s atmosphere
True
(T/F) The atmospheric greenhouse effect occurs on Earth, Venus, and Mars
True
(T/F) The temperature of Earth has measurably risen over the past 100 years.
True
(T/F) The fraction of CO_2 in Earth’s atmosphere is at the highest level measured in the last 450,000 years.
True
Venus is hot and Mars is cold primarily because:
Venus has a much thicker atmosphere.
The atmosphere of Mars is often pink-orange because:
Wind lifts dust into the atmosphere.
Convection in the ______ causes weather on Earth
Troposphere
Auroras are the result of:
The interaction of particles from the Sun and Earth’s atmosphere
The ozone layer protects life on Earth from:
Ultraviolet radiation (the Sun’s rays)
Hadley circulation is broken into zonal winds by:
The planet’s rapid rotation
Hadley circulation
A simplified, and therefore uncommon, atmospheric global circulation that carries thermal energy directly from the equator to the polar regions of a planet
Earth experiences long-term climate cycles spanning _____ of years.
Hundreds of thousands (140,000)
Over the past 800,000 years, Earth’s temperature has closely tracked:
Carbon dioxide levels in the atmosphere
Uncertainties in climate science are dominated by uncertainty about:
Physical causes
Jupiter and Saturn have compositions similar to the sun and are called:
Gas giants
Uranus and Neptune are called:
Ice giants
As depth increases, _____ and ______ increase, causing changes in the chemical composition of clouds in the atmospheres of the giant planets
Temperature and pressure
(T/F) A giant planet has a solid surface that marks an abrupt change from the a gaseous atmosphere
False

-As one travels into the interior of a giant planet, the atmosphere becomes denser, transitioning fairly smoothly into a liquid or solid core

The following steps lead to convection in the atmospheres of giant planets. Place the steps in order.
1. Gravity pulls particles toward the center.
2. Particles fall toward the center, converting gravitational energy to kinetic energy.
3. Friction converts kinetic energy to thermal energy.
4. Thermal energy heats the material.
5. Warm material rises and expands.
6. Expanding material cools.
Consider a northward-traveling particle of gas in Jupiter’s northern hemisphere. According to the Coriolis effect, which way will this particle of gas turn?
In the direction of rotation
Deep in the interiors of the giant planets, water is still a liquid even though the temperatures are tens of thousands of degrees above the boiling point of water. This can happen because:
The pressure inside the giant planets is so high
Oblateness is a property of a planet’s __________; obliquity is a property of a planet’s __________.
Shape; Orbit
Oblateness
The flattening of an otherwise spherical planet or star caused by its rapid rotation
Obliquity
The inclination of a celestial body’s equator to it’s orbital plane (tilted axis)
Imagine a giant planet, very similar to Jupiter, that was ejected from its solar system at formation. (Such objects exist and are probably numerous, although their total number is still uncertain.) This planet would almost certainly still have:
A magnetosphere
Its original composition
Thermal energy
Metallic hydrogen is not:
A metal that acts like hydrogen

-In Jupiter, the magnetic fields are generated within deep layers of metallic hydrogen

(T/F) Uranus has extreme seasons because its poles are nearly in the plane of the Solar System.
True
(T/F) All the giant planets have clouds and belts.
True
(T/F) Water never forms visible clouds in the atmospheres of giant planets.
True
(T/F) Storms on giant planets last much longer than storms on Earth.
True
(T/F) The cores of the giant planets are all similar.
False
Neptune’s existence was predicted because:
Uranus did not obey Newton’s laws of motion.

-Neptune’s gravitational effect on the orbit of Uranus

A stellar occultation occurs when:
An object, such as a planet, moves in front of a distant star.
A stellar occultation can be used to measure the:
Diameter of a planet
The Great Red Spot on Jupiter is:
A storm that has been raging for more than 300 years
The different colors of clouds on Jupiter are primarily a result of:
Composition
Zonal winds on the giant planets are stronger than those on the terrestrial planets because:
The giant planets rotate faster
Weather on Earth is driven by __________; weather on Jupiter is driven by_________.
The Sun; internal energy
The magnetic fields of the giant planets:
Extend far into space
Equilibrium temperature of the Earth (with atmosphere)
288 K
To survive passage through the Earth’s atmosphere without burning or breaking up before it hits the ground, an asteroid must be:
At least 100 meters in size
(T/F) During summer in the northern hemisphere of Mars, the polar ice cap melts and liquid water flows outward from it in rivers.
False
Consider an external solar system in which there are three terrestrial planets. All are located far from other objects so tidal forces aren’t significant. If planet A has a radius of 1 Earth radius, and planet B has a radius of 2 Earth radii, and planet C has a radius of 3 Earth radii, which planet has the highest chance of having at least a partially liquid core and a detectable magnetic field?
Planet C
(T/F) The interior of the Earth is hot mainly because of the pressure induced by the weight of the material above it
False
The Moon has a diameter that is approximately one-fourth that of Earth. If these objects’ interiors are heated by radioactive decays, and the total amount of energy in decays is proportional to the object’s volume, then how does the amount of heat the Moon has compare to that of Earth?
The Moon has 1/64th = 0.016 times that of Earth’s
Which is NOT a reason for the large size of volcanoes on Mars as compared to Earth’s smaller volcanoes?
Lack of atmosphere; therefore no erosion
The large feature spanning the surface of Mars in the figure above is _________ and probably was created by _________.
A canyon; a rapid cooling of the crust
(T/F) On Mars, water ice is present primarily at its polar ice caps.
False
Permanent magnetism in the Earth’s solid iron core is the source of Earth’s magnetic field.
False
What makes carbon dioxide a highly effective greenhouse gas?
It easily absorbs infrared radiation.
The temperature differences between night and day on the Moon and Mercury are very small because they have so little atmosphere.
False
Auroras are caused by:
Gases fluorescing in the atmosphere due to collisions with solar wind particles
What could have caused the planets to migrate through the Solar System?
Gravitational pull from other planets

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