Astronomy Second Semester Review Concepts Study Ideas
The distance between the Earth and the Moon varies as the Moon orbits about the Earth.
Which of the following is not a kind of geological feature found on the Moon? A. Scarp B. Crater C. Maria D. Rille
Basalt, a dense congealed lava rock rich in iron, is the primary material in the Moon's Maria.
One result of bombardment of the Moon's surface is a layer of broken, pulverized, and powdered rock called Regolith.
Based on a comparison between the amount of cratering seen in the highlands versus the maria, it is possible to conclude that the main bombardment of the Moon occurred Shortly after the Moon formed a few billion years ago.
The primary reason the Moon lacks an atmosphere is because. The Moon lacks sufficient gravity to retain an atmosphere.
Which statement about the Moon's orbit is true? A. The Moon is in synchronous rotation as it orbits the Earth. B. The Moon is in a geosynchronous orbit around the Earth. C. The Moon's orbit is aligned with the Earth's orbit. D. The Moon rotates in the opposite direction than it orbits the Earth.
Which of the following theories for the origins of the Moon is general accepted by astronomers? A. The Moon formed alongside the Earth (the twin theory). B. The Moon is the result of a collision between the Earth and a Mars sized object in the early days of the Solar System (the collision theory). C. The Moon was originally a bulge on the Earth that was flung off by the rapidly spinning Earth (fission theory). D. The Moon formed somewhere else and was later captured by the Earth (capture theory).
If the Moon were farther from the Earth, compared to now, the tides would be Less tall all the time.
Why do we always see only one side of the Moon? The Moon is tidally locked with the Earth.
From the observation that the same side of the Moon always faces the Earth, one can conclude that The Moon completes one rotation each time it completes an orbit about the Earth.
When our Earth becomes tidally locked with the Moon, The Moon will always be visible only from one side of the Earth. An astronaut on the Moon would see only one side of the Earth.
Based on our understanding of our own solar system, which of the following would be most surprising to observe in an extrasolar system of planets? A. The planets nearest to the star have a lower density than the planets farther out. B. Several planets show large tilts of their rotation axis compared to the plane of their orbits. C. All the gas giants have moons. D. Several planets have dense atmospheres containing carbon compounds.
Which of the following is not a method used by astronomers to detect and study exoplanets? A. Rotational mapping. B. Gravitational lensing. C. Doppler shift. D. Transit detection. E. Direct imaging
The Sun, the Earth, Jupiter, and Saturn's icy moons are all very different environments. But all formed from the same basic group of chemicals.
Given that Mercury, Mars, and some of the moons of the gas giants are covered with craters, why do we not see lots of impacts happening today? The Sun's heat drove the remaining dust and gas out of the part of the solar system with planets, and gravitational interactions ejected most of the larger debris.
Thinking about the formation of the solar system, what trend in composition would you expect to see from the inside to the outside of the asteroid belt? Rockier asteroids progressing towards ones with more hydrogen and carbon compounds.
How many stars are there in our Solar System? One
How many planets are there in our Solar System? 8
Which planets have densities similar to that of the Earth's? Mars and Mercury.
In our Solar System, an object is called a planet if It orbits the Sun. It has the round shape. It has cleared its neighborhood.
Pluto is classified as a dwarf planet because It has not cleared its neighborhood.
A spherical region that surrounds the Solar System and extends up to about 100,000 AU from the Sun is called the Oort cloud.
What is the name of the nebula from which our Solar System was formed? Solar nebula
Which property of the solar nebula was the most influential in giving the planets their characteristics? Temperature
The process in which a gas cools and its molecules stick together to form liquid particles is called Condensation.
Which was the last part of the planetforming process? Formation of the atmosphere of the planets.
Exoplanets are Planets around stars other than the Sun.
Why is it difficult to observe an exoplanet directly through a telescope? Exoplanets are small compared to their parent star, so they reflect only a small portion of the star's light.
What is gravitational lensing? The focusing and brightening of starlight by the gravitational field of the foreground star, when there is a perfect alignment with the observer.
According to the nebular hypothesis, which of the following sequences of events are chronologically correct? Interstellar cloud, solar nebula, accretion, collisions between planetesimals, planets.
Comets are while asteroids are. Icy; rocky
Small planets do not have significant atmospheres because their is weak. Gravity
Compared to the planets the planets have. Terrestrial; Jovian; many satellites
Astronomers believe that the satellites of the Jovian planets were. Planetesimals orbiting the growing planet.
What features are unique to Earth? Canyons. Volcanoes. An atmosphere. Precipitation. None of these features are unique to Earth.
The red coloration seen on the Martian surface originates from The iron minerals in the surface rocks combining with oxygen in the atmosphere causing the surface to rust.
Which planet has the hottest surface temperature? Venus
The Coloris Basin found on Mercury was probably formed by what process? An impact from a planetesimal.
Which planet has a greenhouse effect? Venus Earth
List the terrestrial planets in decreasing order of their mass. Earth, Venus, Mars, Mercury
Mercury lacks an atmosphere because Its smaller size means it has gravitational attraction that is too weak to hold onto an atmosphere.
Which terrestrial planet has the most moons? Mars
Which planet shows the largest variation of day and night temperatures? Mercury
Which terrestrial planet is tilted upside down? Venus
Which of the terrestrial planets have the most similar atmospheric compositions? Venus and Mars
Which of the other terrestrial planets is closest in size to the Earth? Venus
The surface of Mercury resembles the Moon's surface in that they are both. Heavily cratered
is the smallest of the terrestrial planets. Mercury
is the largest of the terrestrial planets. Earth
The atmosphere of Venus consists mainly of. Carbon dioxide
The clouds of Venus consist mainly of. Sulfuric acid
The Valles Marineris is on the surface of Mars. A 4000 km canyon
The atmosphere of Mars consists mainly of. Carbon dioxide
Mars' axial tilt and spin are most similar to. The Earth's
Mercury's and, therefore, the planet does not have seasons. Axial tilt is zero
Venus extremely high surface temperatures are due to The composition of its atmosphere.
Of all the terrestrial planets, has the largest daily temperature variation. Mercury
Evidence that there is a considerable amount of water frozen under the surface of Mars is provided by all of the following except Periodic eruptions of geysers when subsurface ice is melted by volcanic activity.
Mercury features long, steep cliffs in its crust called "scarps" which probably formed Like giant wrinkles as the crust cooled and shrank.
Maps of Venus have been made by Bouncing radio waves off the planet from satellites and the Earth.
List the outer planets in order of increasing mass? Uranus, Neptune, Saturn, Jupiter
What type of dunes exists on Titan? Ice crystal dunes.
Of the outer planets, has the smallest diameter. Neptune
Which of the out planets has rings? Jupiter. Saturn. Uranus. Neptune. All of the outer planets have a ring system.
Which is the smallest of the outer planets? Neptune
What observational evidence suggests that Uranus was struck by a large planetesimal early in its formation? Uranus' rotational axis is tipped over.
Which is the largest planet? Jupiter
Which planet's rotation axis is closest to its orbital plane? Uranus
Which planet has the most extreme seasons? Uranus
Which planet has the lowest density? Saturn
Which satellite has lakes of liquid methane near its poles? Titan
Although Saturn and Jupiter have similar compositions their outer appearances are different because Saturn's cooler temperatures allow for the formation of a hazy layer of ammonia clouds that surrounds the planet.
How does the mass of Jupiter compare to the rest of the planets in the Solar System? Jupiter's mass is greater than all the other planet masses combined.
What is the largest satellite (moon) in the Solar System? Jupiter's moon, Ganymede
Scientists believe a liquid water ocean might exist on the moon Europa.
What causes the blue appearance of the planet Uranus? Uranus' atmosphere contains methane that strongly absorbs red colors from the sunlight.
What prompted astronomers to search for Neptune? Uranus was not following the precise orbit predicted by Newtonian physics.
The appearance of an aurora indicates that The planet has a magnetic field.
The following are a common characteristics of the Jovian planets Mostly composed of hydrogen and helium. Thick atmosphere. Lack of solid surface. Ring systems and satellites.
What chemical compound is responsible for Uranus and Neptune's color? Methane.
Why do astronomers believe that the Jovian planets are composed mainly of hydrogen and helium? Because the Jovian planets have low densities.
Why do astronomers believe that the Jovian planets must contain rocky material in their cores? Because silicates and irons were part of the overall composition of the solar nebula.
The colors of Jupiter's clouds suggest the presence of. Organic molecules
The powerful Jupiter is a result of the and in the interior of the planet. Wind on; Coriolis effect; heat generated
is the largest of the Galilean moons. Ganymede
The Great Red Spot on Jupiter is. A giant vortex that has persisted for over 300 years
has the lowest density of all the planets in the solar system. Saturn
The rings of Saturn consist primarily of. Water ice
Astronomers believe chondrite meteorites are about 4.6 billion years old formed when the solar system formed because Radioactive dating can be used to determine their age.
All of the asteroids in the asteroid belt together have a tiny fraction of the Earth's mass.
Asteroids need to have enough material to have an average diameter of about for gravity to pull them into a spherical shape. 1000 km
Infrared observations are used to determine the mass of asteroids because The infrared radiation is the glow of heat from the asteroid, and larger asteroids emit more infrared light.
Asteroids Can range is size from a few meters to many hundreds of kilometers.
Fragments that do not completely burn in the atmosphere and eventually fall on the Earth are called Meteorites
A meteor shower occurs when the left over debris of a intersects with our atmosphere to produce the beautiful streaks of light. Comet
Comets belong to the Kuiper belt and Oort cloud.
Planet creates the gaps in the asteroid belt called Kirkwood gaps. Jupiter
The gaps created by the planet Jupiter in the asteroid belt are called. Kirkwood gaps
The short-period comets originate in and the long-period comets originate in. Kuiper belt; Oort cloud
Meteor showers are generally named After the constellation from which they appear to diverge.
Objects of the Kuiper belt were detected by the Hubble Space Telescope.
What is the evidence for the existence of the Oort cloud? The fact that new comets continue to appear indicates that a distant reservoir of icy bodies must exist.
The Leonid meteor shower occurs in mid November. The radiant of the meteor shower is in the constellation of Leo. The shower occurs when the Earth crosses the path of an old comet.
The tail of a comet always points. Away from the Sun
The typical size of a comet's nucleus is. 10 km
Approximately how massive is the Sun as compared to the Earth? 300,000 times
If you could manage to stand on the Sun, you would weigh approximately times more than your weight on the Earth. 30
The sunlight we receive on the Earth originates from the Sun's Photosphere.
The hottest part of the Sun is The core.
The Sun's core is generating energy in the form of. Gamma rays
Sunspots are dark because they are Slightly cooler regions meaning they emit less light than the surrounding areas.
Which part of the Sun is not in hydrostatic equilibrium? Corona
The solar wind is created in the Sun's. Corona
Flare is the name of a sudden, highly energetic, eruptive explosion on the surface of the Sun.
The diameter of the Sun is determined by measuring its and. Distance; angular size
The surface temperature of the Sun can be measured using. Wien's law
The Sun's composition by the % of mass is 71%, 27% and 2%. Hydrogen; helium; other elements
The energy in the Sun's core is produced by Fusion of hydrogen to helium.
The Sun's atmosphere consists of the and the. Chromosphere; corona
provides a way to measure the speed of seismic waves in the Sun. The Doppler effect
The Sun rotates at its equator than at its poles. Faster
A solar prominence is essentially A plasma confined to a magnetic tube sticking out of the surface of the Sun.
Since nuclear fusion in the Sun creates energy from matter, why doesn't it violate the law of conservation of energy? Matter and energy are equivalent, as expressed by Einstein's equation E = mc 2.
Generally speaking, activity on the surface of the Sun is primarily driven by Electromagnetism.
The photosphere Is the layer of the Sun where it transitions from being opaque to transparent.
The Zeeman effect, in which energy levels of electrons are shifted and produce a corresponding split in spectral lines observed, is used to measure at the Sun's surface. Magnetic field strength
The solar cycle is a result of the Differential rotation of the Sun.
Although the Sun's core has a density much greater than rock it is considered a gaseous object because The Sun's high internal temperatures prevent the atoms from bonding together to form a liquid or a solid.
What is parallax? The apparent shift in position of an object caused by a change in the observer's position.
Parallax measurements of the distances to the nearest stars use as a baseline. Earth's orbit
The relative brightness of the stars as we see them in our sky is represented by their Apparent magnitude
Luminosity (absolute brightness) of a star depends on its. Temperature and Radius
If it were possible to move a star closer to the Earth then its apparent magnitude number would while its absolute magnitude number would. Decrease; stay the same
80% of type stars have orbiting companions. O and B
In which binary system can we observe both the stars separately and follow their orbits around each other? Visual binary system.
The H-R diagram is a diagram plotting the stars according to their Luminosity and temperature.
The star Aldebaran is a red giant, and is much more luminous than the Sun. What conclusions can be drawn from this fact? Aldebaran is cooler than the Sun, but has larger diameter than the Sun.
The star Aldebaran is cooler and much more luminous than the Sun. Where do you expect to find Aldebaran in the H-R diagram? Top right
Binary star systems are very important because they allow Measurement of star masses.
What is the difference between spectroscopic and visual binaries? In a visual binary we can see two distinct stars; in spectroscopic binaries, the images of the two stars can not be resolved.
The study of eclipsing binary stars is very important because it allows astronomers to determine The diameters of stars
Stars on the main sequence have different luminosities because They have different masses.
If a main sequence, giant, and a supergiant all have the same spectral class, what characteristic is known to make these stars different? Luminosity.
can be used to measure the of nearby stars. Interferometry; radius
The parallax of a star is usually measured in. An angle; arcseconds
The amount of energy emitted by a star each second is the and is measured in. Luminosity; Watts
The luminosity of a star is determined by the star's and. Diameter; surface temperature
The Balmer lines correspond to wavelengths in the part of the spectrum of a atom. Visible; hydrogen
binary star systems are important because they allow astronomers to determine the mass and the of the stars in the system. Eclipsing; diameter
White dwarfs have spectral lines than red giants. Wider
How does Rigel, a bluish star, surface temperature compare to Betelgeuse, a reddish star. Rigel's surface temperature is greater than Betelgeuse's.
Brown dwarfs are Object massive enough to fuse deuterium but not massive enough to sustain hydrogen fusion.
The most important property that determines the evolution of a star is its Mass.
When do we say that a star is born? When fusion of hydrogen atoms into helium atoms start.
Protostars shine brightest in Infrared.
If a star is in hydrostatic equilibrium Its radiation pressure outwards and gravitational forces inwards are in balance.
In which stage of a star's evolutionary cycle does it spend the most time? The main sequence.
The process in which two or more lighter elements combine to form a single heavier element is called Nucleosynthesis.
When the outer envelope of a red giant is ejected, the remaining exposed core of a low mass star is called a White dwarf.
After a star leaves the main sequence It now fuses hydrogen into helium in a shell outside the core.
What characteristic do all stars on the main sequence share? They are all fusing hydrogen into helium in their cores.
What makes variable stars useful in determining star distances? Their luminosity can be determined from their pulsation period.
How do most of the heavier elements up to iron form in the Universe? By nucleosynthesis in the cores of massive stars.
How do astronomers test models of stellar evolution? By comparing the paths in the H-R diagram predicted by models with the H-R diagrams of star clusters.
The Sun formed from the gravitational collapse of a cold. Interstellar cloud
is the most significant force that determines the evolution of stars. Gravity
When a star moves off the main sequence and becomes a red giant it is brighter because The size of the star increases.
Hydrostatic equilibrium is the balance between of a star and. The internal pressure; gravity
The CNO cycle produces energy by fusing Hydrogen into helium.
After the hydrogen in the star's core is depleted the core shrinks and heats up.
During a star's main sequence portion of its life it does not change size appreciably. This observation indicates that The Sun produces about the same amount of energy as it radiates into space.
The last fusion product possible in stars is because. Iron; fusing iron nuclei absorbs energy; it does not liberate it
are hot, compact stars whose mass is comparable to the Sun's and size to the Earth's. White dwarfs
A happens when a single high mass star explodes. Type II supernova
This event recurs and happens when one of the companions in the binary system is a white dwarf. Nova
are hot, compact remnant stars whose mass is typically between one and several times that of the Sun, but their size is only 10 km or less. Neutron stars
Two important properties of young pulsars are Extremely rapid rotation and a strong magnetic field.
The escape velocity inside a black hole is Greater than the speed of light.
A method for identifying a black hole is to Look for its effect on nearby companions.
The Chandrasekhar limit is the largest a white dwarf can have. Mass
The temperature of black holes is estimated to be. Less than 1 millionth of a degree
Black holes emit radiation in the form of waves known as Hawking radiation. Electromagnetic
The first pulsars were observed using telescopes. Radio
The fast rotation of neutron stars is a consequence of. The law of conservation of angular momentum
Astronomers use to determine the magnetic field of white dwarfs. The Zeeman splitting of spectral lines
Why do white dwarfs have high temperatures? Heat left over from their formation
Gravitational waves Are traveling distortions of space and time.