Intro to Astronomy Final Exam
If we could see the full extent of the magnetosphere of Jupiter from the Earth, how big would it appear in the sky?
16 times larger than the full Moon
The surface temperature of Titan, the largest moon of Saturn, is
95 K (-178°C).
By what angle is the rotation axis of Uranus tilted from the vertical to its orbit?
98°
Recent calculations show that the Tunguska explosion in Siberia in 1908 was probably caused by
A small stony asteroid about 80 m across exploding well above the ground.
What is the difference between an Apollo asteroid and an Amor asteroid?
Apollo asteroids cross the orbit of Earth, whereas Amor asteroids cross the orbit of Mars but not Earth's orbit.
Asteroids whose orbits carry them across Earth's orbit are known as
Apollo asteroids.
A chunk of rock and metal 10 km in diameter orbiting the Sun would be called a(n)
Asteroid
What is unique about the Pluto-Charon system, compared with all other planets in the solar system?
Both Pluto and Charon are in synchronous rotation, so each object maintains the same face toward the other object at all times.
Most meteorites show evidence of having melted or of being fragments of asteroids that were once differentiated by heat. Carbonaceous chondrites, however, are believed to have never melted. Which one of the following sentences is NOT a reason we believe carbonaceous chondrites have never melted?
Carbonaceous chondrites do not show fusion crusts after passage through Earth's atmosphere.
What is the largest known asteroid in our solar system?
Ceres
How would Interplanetary Travel, Inc., advertise a holiday on Titan, one of the satellites of Saturn?
Exquisite ethane lakes, hydrocarbons beyond your wildest dreams, no shortage of fuel!
Which characteristic of Jupiter's satellite Io makes it different from any other known satellite in the solar system?
Io is volcanically active, with gas plumes and lava flows.
What effect does Jupiter have on asteroids in the asteroid belt?
Jupiter perturbs only the orbits of asteroids whose orbital periods are a simple fraction (e.g., 1/2, 1/3, 2/3, 2/7) of its orbital period.
Why does no major planet orbit the Sun at the location of the asteroid belt?
Jupiter's gravitational pull stirred up the planetesimals, preventing them from coalescing into a single large object.
The most likely origin of the "dirty snowballs" that become comets when they are deflected into orbits that bring them closer to the Sun is the
Kuiper belt and Oort cloud surrounding the solar system.
The luminous trails of small dust particles that are completely vaporized in Earth's atmosphere are known as
Meteors
Saturn's atmosphere does not show the same colorful contrast that we see in Jupiter's atmosphere because
Saturn has a similar circulation pattern to Jupiter's, but it is obscured by a thick hazy atmosphere
A few of the largest asteroids appear to be spherical. How do you think they got this way?
Self-gravity was sufficient to pull the largest asteroids into a spherical shape during their early history.
How would we be able to detect a large asteroid if it were heading straight for Earth?
The asteroid would appear as a slowly brightening point of light where no star had previously been charted, and the spectrum of sunlight reflected from it would be blueshifted by the Doppler effect.
What defines a comet as a long-period comet?
The comet has a period longer than 200 years
What is considered to be the most likely origin of the comets in the Oort cloud?
The comets in the Oort cloud formed near the orbits of Uranus and Neptune and were flung outward by the gravitational influence of these two planets.
Why do the meteors that are seen in the sky in a particular meteor shower appear to come from one specific direction in the sky?
The meteors appear this way because the direction is that of the orbit of the comet that disintegrated to produce the shower.
Why are carbonaceous chondrites thought to be original material that formed in the early solar nebula?
The minerals of a carbonaceous chondrite contain up to 20% water, which would have evaporated away if the chondrite had been strongly heated.
What is perhaps the most striking feature of the dimensions of the rings of Saturn?
The rings are extremely thin compared to their lateral extent.
Why is the F ring much narrower than the main rings?
Two "shepherd" satellites focus the particles into a narrow ring.
The Kuiper belt is
a flat or donut-shaped distribution of distant comets around the Sun, extending out about 500 AU.
The structure of Callisto, the outer Galilean satellite of Jupiter, is thought to be
a mixed ice-rock interior surrounded by a liquid ocean and then a solid icy crust.
Based on its mean density, the dwarf planet Pluto appears to be composed of
a mixture of rock and ice.
An asteroid is
a planetesimal moving in an orbit around the Sun.
The physical structure of Saturn's rings is
a sequence of many thousands of separate ringlets consisting of ice blocks and ice-coated rock.
The surface of Europa, one of the Galilean moons of Jupiter, appears to be covered with
a smooth layer of ice crossed by many cracks.
The Oort cloud is
a spherical distribution of distant comets around the Sun, extending out about 50,000 AU.
The mass of Jupiter compared with that of the Earth is
about 300 times larger.
How thick are the cloud layers on Jupiter's visible "surface"?
about 60 km
What gives Uranus its blue-green coloration?
absorption of red light by methane gas
The general shape of each of the Galilean moons of Jupiter is
almost perfectly spherical.
The astronomical event that is now thought to have occurred some 65 million years ago, resulting in the death of a large fraction of all living species and leaving a layer of clay containing an enhanced concentration of a rare metal, iridium, in the geological record in rocks throughout Earth was a(n)
asteroid impact on Earth.
The lifetime of the Great Red Spot of Jupiter appears to be
at least 300 years, from visual records.
In a single photograph of a comet and its tail, the only direction that one can determine with certainty is the direction
away from the Sun because the tail is pushed in this direction by the solar wind.
How was the dwarf planet Pluto discovered?
by searching photographs of the sky for an object that moved against the background of distant stars
The orbits of periodic comets
can extend far out beyond the orbit of Pluto and can be oriented in any direction in the solar system.
Which meteorites are believed to be samples of primordial solar nebula material?
carbonaceous chondrites
The major difference between the orbital paths of comets that we see in the inner solar system and those of the asteroids in the asteroid belt is that
cometary orbits are highly elliptical and at random inclinations to the ecliptic plane compared with the circular orbits of asteroids in the ecliptic plane.
The dust tail of a comet has which group of characteristics?
curved, wide, and without structure, but thin and transparent to starlight
What has been discovered in some meteorites that suggests that the formation of our Sun and solar system might have been triggered by a supernova explosion?
decay products of short-lived radioactive elements, which only could have been produced in intense nuclear reactions
What technique has allowed scientists to determine the relative sizes of Pluto and Charon?
eclipses of the planet's surface by its moon, Charon, during 1985-1990, viewed from Earth
The rings of Saturn are in which plane with respect to the planetary system?
equatorial plane of Saturn
Which chemical in the atmosphere of Titan (a moon of Saturn) plays the same role that water plays on Earth by producing "rain," "snow," and "ice" at the temperature encountered on Titan?
ethane, C2H6
Interplanetary material
falls on Earth at the rate of several hundred tons per day, mostly as micrometeoroids.
What mechanism controls the direction in which a comet's ion tail is aligned in space?
flow of solar wind past the comet's head
The overall interior structure of the Jovian planets is expected to be
four-layered: a rocky core, a semifluid ice layer, a liquid mantle of hydrogen, and a gaseous hydrogen and helium atmosphere.
The main gravitational effect that organizes the particles in the rings of Saturn into specific narrow orbits is
gravitational perturbations by the large moons orbiting these planets.
The temperature in the core of Jupiter is
hotter than the temperature of the Sun's surface but cooler than the temperature of the Sun's core, so nuclear fusion cannot take place.
What are the most abundant gases in the atmosphere of Uranus?
hydrogen and helium, with traces of methane
To what does the term plutino refer?
icy object orbiting the Sun in the region of Pluto
Where do the Trojan asteroids orbit the Sun?
in circular orbits at the same orbital distance as Jupiter
The particular feature of a comet that exhibits the most structure and always points away from the Sun is its
ion or gas tail.
The nucleus of a typical comet is
irregular in shape, with a very dark and cratered surface.
The gas and ion tail of a comet
is always blown away from the comet in the anti-Sun direction by the solar wind.
The material that composes the rings of Jupiter
is continually being ejected from the rings and being replenished from material from the Jovian moons.
Meteoroid is the term used to describe a solid particle that
is drifting around in space.
Saturn's moon Titan is different from all other moons of the planets because
it possesses a thick atmosphere.
What is Sedna?
largest object discovered beyond the orbit of Pluto
What characteristic features are seen on the visible surface of Jupiter?
light and dark bands parallel to the equator
The material in the interior of Jupiter that is thought to be responsible for its powerful magnetic field is
liquid metallic hydrogen.
Saturn, like Jupiter, is composed primarily of
liquids.
What is the average distance between asteroids?
many times the distance between Earth and the Moon
Comet tails are the result of
melting and evaporation of ices from the comet core.
A piece of rock from outer space that reaches Earth's surface after surviving a fiery passage through Earth's atmosphere is known as a(n)
meteorite.
A small particle of rock orbiting the Sun would be called a
meteoroid.
Recent observations suggest that Saturn's satellite Enceladus possesses all the following features except one. Which feature does Enceladus probably NOT possess?
molten lava flowing from active volcanoes
The total number of asteroids orbiting the Sun among the planets is estimated to be
more than a million.
The particles in Saturn's rings
move in circular Keplerian orbits; the inner particles move fastest.
Jupiter has a magnetic field that is
much more powerful than that of the Earth.
If you were standing on Pluto, how often would you see the satellite Charon rise above the horizon each day?
never—Charon is a synchronous satellite with an orbital period exactly equal to Pluto's rotation period
The composition of the atmosphere of Titan, a satellite of Saturn, is mostly
nitrogen, methane, and other hydrocarbons.
What features dominate the surface of Ganymede, one of Jupiter's satellites?
old, dark, highly cratered polygons separated by younger, lighter, grooved terrain
Most meteor showers occur when Earth moves through the
orbit of a comet (or of a former comet).
A meteor shower, or the appearance of many more "shooting stars" at a particular time in the year from a specific sky direction, is related to which astronomical phenomenon?
passage of Earth through the remnants of an old comet
Most comet nuclei are believed to be
pieces of dusty ice left over from the formation of the solar system
The nucleus of Comet Halley, as seen on close-up photographs taken by the Giotto spacecraft, is
potato-shaped and darker than coal.
largest object discovered beyond the orbit of Pluto
radiation pressure
The orbits of comets are
randomly oriented in the solar system and can extend far beyond the orbit of Pluto.
The rings of Saturn are seen by
reflected and scattered sunlight.
One interesting feature of Jupiter's rotation is the fact that
regions of Jupiter at different latitudes appear to rotate at different rates.
The rotation period of Jupiter is
relatively short, on the order of 10 hours.
What is believed to be the basic structure of the interior of Uranus?
rocky core, thick layer of highly compressed liquid water, thick outer layer of liquid hydrogen, thin gaseous atmosphere
What is the interior structure of Saturn?
rocky core, thick mantle of liquid metallic hydrogen and helium, relatively thin gaseous atmosphere
If an asteroid were found to be orbiting in a circular path around the Sun at the same distance as Jupiter (5.2 AU), what would be its orbital period compared with that of Jupiter, which is 11.86 years?
same as Jupiter's period, 11.86 years
What kind of ring or rings does Jupiter have?
several thin dark rings made up of very fine dust particles
The composition of the clouds we see on Jupiter is
similar to the composition of the Earth's clouds (water droplets and crystals of frozen water) in the lower levels but very different (ammonia crystals and other chemicals) in the higher levels.
A shooting star is a
small particle of interplanetary dust burning up and glowing as it enters Earth's atmosphere.
The rotation periods for the Jovian planets Jupiter, Saturn, Uranus, and Neptune are
somewhat shorter than that of the Earth, between 10 to 20 hours.
The most common meteorites to hit Earth are
stony meteorites.
In order of abundance, from most abundant to least abundant, the occurrence of meteorite impacts ("falls") is believed to be
stony, iron, stony iron
The Kirkwood gaps are caused by
the gravitational pull of Jupiter, which nudges asteroids into new orbits.
The existence of the Great Red Spot of Jupiter has been known since
the time of Hooke and Cassini in the 1600s.
The expected seasonal changes on Uranus because of its orbital and spin-axis alignments, compared with those on the Earth, are
very much exaggerated.
Compared with the coma, or the visible fuzzy ball, of a comet 106 km in diameter, the diameter of the nucleus of the comet is
very small, about 1/105, or 10 km.
What is the Cassini division?
wide, dark gap in Saturn's rings
