Comets, Meteors, and Asteroids





for two satellites with the same mean distance from the Earth to rendezvous, the lagging satellite must

A speed up

B slow down

C change direction

D no choice



the general shape of most asteroids is thought to be

A irregular, odd shape

B perfectly spherical

C loose collections of very small particles, held together by gravity

D double, two asteroids orbiting the sun together



the primary chemical constituent of comets is:

A co2.

B nitrogen.

C h2o.

D methane.



the kirkwood gaps result from

A radiation pressure from the sun.

B the previous passage of a comet through the asteroid belt.

C regular gravitational pull from the largest of Jupiter's moons.

D regular gravitational pulls from Jupiter.

E previous explosions of asteroids at points in the asteroid belt.



a meteor shower occurs when

A a meteor is about to get married

B the Earth passes through the asteroid belt

C the Earth passes through a swarm of dust particles in space, the remnants of a comet, once per year

D the head of a comet hits the Earth's atmosphere



a meteorite is

A a rock or grain of sand passing through the Earth's atmosphere

B the trail left by a rock or piece of sand as it passes through the Earth's atmosphere

C a rock from space that strikes the ground

D all the above



a cometary nucleus has a diameter of roughly

A 10 km

B 100 km

C 1,000 km

D 100,000 km



the expected (and now measured) size of the core of a typical comet nuclei is about

A 10(7) km

B 10 km

C 100 m

D 10(6) km



the lack of a lunar atmosphere can most conclusively be observed by

A measuring occultations

B measuring lunar temperatures

C measuring the moon's albedo

D no choice



when a comet breaks up, the resultant particles are called

A meteorites

B meteors

C meteoroids

D no choice



most of the asteroids orbit the sun in a belt between the orbits of

A Venus and Mars

B Mars and Earth

C Jupiter and Saturn

D Mars and Jupiter



kirkwood gaps are caused by

A the gravitational perturbations of Jupiter

B unknown interplanetary forces

C the gravitational perturbations of Jupiter's moons

D no choice



the asteroids are

A pockets of gas in the solar system

B miniature planets

C satellites of planets

D planets orbiting stars other than the sun



the orbits of most comets which we see in the inner solar system

A are nearly circular

B are only slightly inclined to the Earth's orbit

C are highly elliptical

D never come closer to the sun than 5 au



the Trojan asteroids occupy what type of orbits in the solar system?

A circular orbits at the same distance from the sun as Jupiter

B circular orbits at about 2.8 A.U. from the sun

C long elliptical orbits ranging from Neptune's orbital distance to Jupiter' orbital distance

D long elliptical orbits which cross that of Earth



meteors often are the remnants of

A stray asteroids

B comets

C exploded or collided satellites

D volcanic debris from the Earth



the estimated total in fall of meteoritic and extraterrestrial material fro space per day upon the Earth is

A less than 1 ton

B about 1 million tons

C about 10 tons

D about 300 tons



giotto and Vega images of Halley's comet show it to have a:

A highly reflective nucleus of water ice.

B rocky nucleus with a reflectivity about like that of the moon or Mercury.

C very dark nucleus so that it reflects only about 4% of the light it receives.

D no surface features or characteristics that could be observed.



that widmanstatten patterns are found in meteorites implies:

A that they were formed on the surfaces of large viscous bodies.

B that they were formed as small bodies alone in space.

C that they were recently exposed to very high temperatures.

D that they were formed near the center of a much larger body.



the Trojan asteroids

A were first discovered by greed astronomers

B are located where Mars' gravitational pull balances that of the sun

C are located at Jupiter's lagrangian points

D are the ones most likely to intercept the Earth's orbit



what are the Trojan asteroids?

A the Trojans have orbits like that of Jupiter.

B the Trojans are asteroids that cross the orbit of the Earth.

C the Trojans orbit between the sun and Mercury.

D the Trojans are a band of asteroid-like bodies that orbit Jupiter far beyond its moon system.



the chondrite is a meteor that has

A never been heated.

B been heated, but not very hot.

C been heated to high temperature.

D been melted.



a comet's gas tail is always aligned in a direction, from the comet head

A towards the sun, because of gravitational attraction

B in a direction along its orbital path, always behind the comet

C away from the sun

D towards the nearest planet, because of mutual gravitational attraction



cometary nuclei are composed of

A gravel embedded in frozen gasses

B carbonaceous compounds

C nickel-iron compounds

D hydrogen and helium



periodic comets have lifetimes on the order of

A billions of years

B millions of years

C thousands of years

D no choice



most common meteors are

A dying stars

B black holes colliding with the Earth's atmosphere

C chunks of antimatter colliding with the Earth's atmosphere

D bits of rock colliding with the Earth's atmosphere



meteorites

A have all been found to have ages much less than the Earth's

B are chunks broken off from planets

C have been found to contain amino acids

D possess strange new elements never found on Earth



most of the asteroids orbit the sun in a belt between the orbits of

A Venus and Mars.

B Mars and Earth.

C Jupiter and Saturn.

D Mars and Jupiter.



the nucleus of a comet could likely fit into a space the size of

A an average city

B a small state

C the entire Earth

D the sun



the Apollo asteroids

A pass within Earth's orbit

B are at the lagrangian points on Earth's orbit

C are at the lagrangian points on Mercury's orbit

D none of the above



which of the following bio-chemical materials has been found and identified in rocks recovered from outer space?

A amino acids

B lichens and mosses

C viruses

D living cells



an asteroid could produce an iron core and a silicate mantle if it

A differentiated

B out gassed

C condensed

D accreted



meteors are

A really falling stars

B luminous trails left by small extraterrestrial particles rapidly passing through the air

C solar wind particles captured by the Earth's magnetic field

D signals from other worlds



meteorites are composed of

A hydrogen ices

B helium ices

C heavy elements like silicon

D all the above



a meteor is

A a rock or grain of sand passing through the Earth's atmosphere

B the trail left by a rock or piece of sand as it passes through the Earth's atmosphere

C a rock often found in a museum

D a solar wind particle trapped in the Earth's magnetic field



an asteroid could produce an iron core and a silicate mantle if it

A differentiated.

B out gassed.

C condensed.

D accreted.



if all the material in the asteroid belt were in a single body, the mass o this body would be roughly that of

A the moon

B the Earth

C Jupiter

D none of the above



the asteroids trapped at the lagrange points are called

A amor asteroids

B Apollo asteroids

C kirkwood asteroids

D Trojan asteroids



chiron is a recently discovered planetary body which orbits the sun between the orbits of

A Mars and Jupiter

B Jupiter and Saturn

C Earth and Mars

D Saturn and Uranus



comet tails are the result of

A melting and evaporation of ices from the comet core

B interplanetary material streaming into the comet

C sunlight glinting from the central comet core

D dust collected by the comet as it moves in its orbit



from the observations of giotto to Halley's comet, we now know that the nucleus of this famous comet

A is irregular in shape.

B is very dusty.

C shows jets of gas.

D is about 10 km in size.

E all of these.



comets consist of

A roughly the same materials as the inner planets do

B roughly the same materials as the giant planets do

C the most primitive, least altered material in the solar system

D the most recently formed material in the solar system



the asteroid belt exists between the orbital distances of which planets?

A Jupiter and Saturn

B Venus and Earth

C Mars and Jupiter

D Earth and Mars



most meteors are

A bits of rock in orbit about the sun

B bits of antimatter annihilating in the Earth's atmosphere

C small black holes passing through the Earth

D literally "falling stars"



the orbits of most comets which we see in the inner solar system

A are nearly circular.

B are only slightly inclined to the Earth's orbit.

C are highly elliptical.

D never come closer to the sun than 5 au.



comets shine by

A reflected sun light

B florescence

C phosphorescence

D no choice



meteorites indicate to us about the origin of the solar system that

A the solar system formed about 4.6 billion years ago.

B no solid matter was present at the formation.

C metallic and rocky materials condensed early on.

D (a) and (b).

E (a) and (c).



asteroids which orbit the sun at the same distance as Jupiter are known as

A Apollo asteroids

B jupitoids

C Trojans

D adenoids



the grouping of Jupiter's moons into three groups is based on

A differences in orbit characteristics

B differences in chemical composition

C more or less arbitrary differences

D no choice



the widmanstatten patterns found in some meteorites show that

A the material cooled very slowly.

B the material cooled very fast.

C the material was never heated.

D the material was heated, but not very hot.



a bit of matter that enters the Earth's atmosphere and survives to reach the ground is called

A a meteor.

B a meteoroid.

C a meteorite.

D a minor planet.



the most common meteorites to hit the Earth are

A the stony-iron meteorites

B the carbonaceous chondrites

C the stony meteorites

D the iron meteorites



a comet's tail

A precedes its head through space.

B follows its head through space.

C is farther from the sun than its head is.

D is closer to the sun than its head is.

E none of the above.



a comet is

A a rock

B a ball of frozen gases

C a collection of rocks held together by frozen gases

D of unknown composition.



a comet's tail results when

A part of the comet drifts in the direction opposite to the motion of the comet.

B the solar wind carries some of the gas of the coma away from the comet.

C gravitational force pulls loosely held material from the sun.

D tidal forces tear the comet apart.



the tail of a comet always

A trails behind the head.

B extends ahead of the head.

C points toward the sun.

D points away from the sun.



libration is

A a necessary condition for an eclipse

B a small motion of the Earth's axis

C the phenomenon that enables us to see more than half of the moon's surface

D a consequence of the velocity of escape



the combined matter in the asteroid belt would produce an object of what approximate size?

A only a few km in diameter

B about the size of Earth

C about 1500 km in diameter, significantly smaller than the moon

D about the size of Mercury



the tail of a comet points

A away from the sun

B along the comet's orbit

C perpendicular to the direction of the comet's orbit

D no choice



volcanic activity on the lunar surface is

A contrary to most theories of lunar structure

B useful in explaining certain surface features

C conclusively proved by photographs

D all of the above



the cause of the "meteor showers", seen at regular times each year upon Earth, is most probably

A gravitational distortion of the Earth's atmosphere by the moon

B sunspot activity and the resultant geomagnetic disturbance

C the remnant dust and rock fragments from an old comet, circling the sun in the comet's old orbit

D the Earth running into material within the spiral arm structure of the mil way



in order to estimate the size of an asteroid from the amount of light it reflects, one must make an assumption about

A its albedo

B its distance from the sun

C its density

D its temperature



the interplanetary medium is composed of particles which

A were blown from the sun

B escaped from the planets

C was captured by the solar system from the interstellar medium

D are left over from the cloud from which the solar system formed



meteorites are composed of

A stony chondrites

B iron compounds

C stony-iron mixtures

D all of the above



a meteor seen in the Earth's atmosphere is usually

A a dying star

B a projectile ejected from the sun

C an anti-matter object

D an ordinary rock burning up in the air



on June 30, 1908, an object from outer space collided with the Earth and completely destroyed part of a forest in central Siberia. most astronomers believe that this body was

A a disabled UFO that accidentally collided with the Earth

B a small comet that collided with the Earth

C a nuclear device that was launched by an unfriendly space power outside the solar system

D a tiny black hole that passed through the Earth leaving a trail of devastation in its wake



carbonaceous chondrites

A are debris from sun-grazing comets which broke up

B are thought to be similar to materials of the solar nebula

C are fossil remains from the carboniferous period

D are iron meteorites, not commonly found



the dust tail of a comet:

A is pulled from the coma by tidal forces from the sun.

B is pushed out of the coma by solar wind particles and by the solar magnetic field.

C is pushed out of the coma by radiation pressure from electromagnetic radiation from the sun.

D is "boiled" off the coma by heat from the sun.



stony meteorites are of interest to scientists looking for

A signs of crude life away from the Earth

B new chemical elements

C rare minerals

D no choice



the asteroids are thought to be

A the remains of a planet shattered by Jupiter's gravity.

B material prevented from forming a planet by Jupiter's gravity.

C escaped satellites of Jupiter.

D leftover debris from mining operations carried out by an ancient (and stupid) civilization.



the dust tail of a comet:

A points almost directly toward the sun.

B trails behind the comet in the direction from which it came.

C points away from the sun but lags because of the speed of the comet.

D points nearly directly away from the sun.



the Trojan asteroids orbit the sun in circular orbits at the same distance as which planetary body?

A Mars

B the asteroid belt

C Jupiter

D Earth



from spacecraft flyby observations, we now know that the nucleus of Halley's comet is

A spherical in shape and covered with a light-colored dust.

B spherical in shape and covered with a dark dust.

C irregular in shape and covered with a dark dust.

D irregular in shape and covered with a light-colored dust.



most astronomers now believe the asteroids are

A remnants of a destroyed planet

B remnants of an escaped Martian moon

C left over solar-nebula material

D planetesimals in the process of becoming planetoids



which of the following expressions characterized the composition of a cometary nucleus.

A dirty snowball

B muddy rock

C hail stone

D rain drop



most comets are thought to:

A have been formed with the solar system and are permanent members of it.

B have been captured and have become permanent members of the system.

C have been formed with the solar system but will leave once they come close to the sun.

D have been captured and will leave once they come close to the sun.



the Oort cloud is located

A between the orbits of Mars and Jupiter.

B just beyond Pluto's orbit.

C far beyond the orbit of Pluto.

D at about the distance of the nearest star.



asteroids are

A extremely small planets

B moons of Jovian planets

C useful (but hypothetical) constructs when applying bode's law

D no choice



short-period comets all

A share the same orbital plane with the nine planets

B have orbital periods less than a year

C actually have orbital periods which are hundreds of thousands of years long but still are shorter than most comets'

D have had their orbital paths changed by interaction with a giant planet



what do widmanstatten patterns in meteorites indicate about their origins?

A they were formed in the presence of external magnetic fields.

B they were formed in the presence of external electric fields.

C they were formed with very high temperatures and cooled slowly.

D they were formed at low temperatures.



the visible coma of an active comet near the sun may be as large as

A 100 km

B 1,000 km

C 10,000 km

D 100,000 km



a stationary observer on the moon will, in most places, see the Earth rise

A about every 27 days

B about every 29 days

C every 24 hours

D never



compared to the moon, the biggest asteroid is

A between 1/3 and 1/4 as big

B about the same size

C very much bigger (greater than x5)

D very much smaller (less than 1/10)



today, astronomers believe that asteroid belt consists of ______, which probably resemble the planetesimals that formed the ______ planets

A debris from an exploded planet, Jovian

B debris from an exploded planet, terrestrial

C debris from the solar system's formation, Jovian

D debris from the solar system's formation, terrestrial



the mass of a comet is

A much greater than the Earth's mass

B much less than the Earth's mass

C about the same as the Earth's mass

D no choice



a comet's gas and ion tail

A lies between the comet and the sun, because of gravitational attraction

B always trails along the orbital path, because of friction

C is always blown away from the comet in the anti-sun direction by the solar wind

D always lies in the ecliptic plane, since a comet can be considered part of the solar system



the most likely origin of the "dirty icebergs", which became comets when t are deflected into orbits which bring them close to the sun, is

A the asteroid belt

B the Oort cloud surrounding the solar system

C the gas clouds in the milky way

D the atmosphere of Jupiter



which of the following types of objects typically have the most stretched out orbits

A asteroids

B comets

C planets

D planetary satellites



the tail of a comet is

A blown from the coma by the solar wind

B swept off by the high speed of the comet near perihelion

C an optical illusion

D no choice



the ion tail of a comet:

A is pulled from the coma by tidal forces from the sun.

B is pushed out of the coma by solar wind particles and by the solar magnetic field.

C is pushed out of the coma by radiation pressure from electromagnetic radiation from the sun.

D is "boiled" off the coma by heat from the sun.



according to the Oort cloud theory short period comets:

A are caused by condensations close to the sun.

B are produced when the comet condenses near Jupiter and is thrown in toward the sun.

C may result when long period comets are disturbed by the gravitational attraction of Jupiter.

D are the ones that belong to the solar system and long period ones are not permanent members of the system.



shooting stars are actually

A small bits of debris

B rocks

C asteroids

D remnants of an exploding star



no disc is seen (even in a large telescope) of

A Mercury

B asteroids

C Mars at conjunction

D no choice



comets in hyperbolic orbits are probably

A the result of errors in measurement

B new to the solar system

C recently perturbed from elliptical orbits

D no choice



the meteorites we see in museums probably did not originate in

A comets.

B asteroids.

C the layers of small bodies later broken up by collisions.

D all of these



a meteor shower occurs when

A the Earth intercepts a comet

B the Earth intercepts the fragments of an old comet

C two comets collide

D no choice



c type asteroids

A are more common in the outer asteroid belt.

B are very dark material.

C resemble carbonaceous chondrites.

D all of these.



some meteor showers return each year at predictable times. meteor showers are thought to be due to:

A fragments of asteroids that have been crushed by collisions with other bodies.

B Apollos that collide with the Earth.

C the Earth passing through a solar ring system similar to that of Saturn's.

D the Earth colliding with debris left by comets.



a carbonaceous chondrite is a type of

A comet

B asteroid

C moon rock

D meteorite



the asteroids are composed of

A metallic compounds

B carbonaceous compounds

C silicon-bearing compounds

D all of the above



the dust tail of a comet has the following characteristics

A long, straight, structured and pointed directly away from the sun

B amorphous (without structure), curved, wide but thin and transparent to starlight

C narrow, straight, pointed directly at the sun at all times

D spherical, low brightness, showing up only on UV photographs, centered upon the comet nucleus



why are meteorites and comets important in studying the origin of the solar system?

A they have recently formed, themselves.

B they are recently produced fragments of planets.

C they represent the material which formed the planets.

D none of the above.



one theory suggest that the bodies in the Oort cloud formed

A near the present orbits of the terrestrial planets

B near the present orbits of the Jovian planets

C at high temperatures

D from silicate materials



the moon's albedo of 0.07 means that

A the moon reflects only a small part of the light that hits it

B the moon reflects most of the light that hits it

C there is no protective lunar atmosphere to shield the surface

D no choice



which of the following do not represent an observed lunar surface feature?

A craters

B maria

C nodes

D mountains



librations allow us to see

A lunar phases

B more than 50% of the moon's surface

C lunar eclipses

D no choice



the coma of a comet may be, in terms of size, as large as

A the Earth

B the moon's orbit around the Earth

C the Earth's orbit around the sun

D no choice



where are the orbits of most asteroids found?

A between the orbits of Mars and Jupiter

B between the orbits of Jupiter and Saturn

C around Jupiter

D between the orbits of Earth and Mars.



spectroscopic measurements of the coma of a comet reveal

A light atoms (hydrogen, helium)

B heavy atoms (carbon, oxygen)

C fragments of simple molecules (water, carbon dioxide, carbon monoxide)

D fragments of complex molecules (alcohol, acetylene, formaldehyde)



comets are thought to be debris from which the______ formed.

A outer planets (Jovian planets and Pluto)

B inner planets (terrestrial planets)

C asteroids

D household cleaner

E ford mustang



the retrograde satellites of Jupiter are thought to be

A satellites captured from other planets

B captured asteroids

C natural satellites

D no choice



the tail of a comet

A remains constant throughout its complete orbital path

B is longest when the comet is furthest from the sun, since it is then unaffected by sunlight

C is longest when the comet is closest to Earth

D is longest when the comet is closest to the sun



astronomers now believe that long-period comets originate in

A the Oort cloud

B the asteroid belt

C the sun

D the rings of the outer planets



the ionized gas tail of a comet is aligned with

A the comet's direction of motion

B the line between the comet and the nearest planet to it in its orbital plane

C the comet-sun line

D the celestial equator



the discovery of radioactive aluminum and its byproduct in the allende meteorite suggests that

A comets are the parent bodies of meteor shower materials

B the dinosaurs may have been killed by the impact of the allende meteorite

C energetic nuclear processes occurred in this cosmic neighborhood just before the solar system formed

D the allende meteorite must have come from the Oort cloud



since the moon always keeps the same side toward the Earth it must rotate about its axis

A not at all

B once per revolution about the Earth

C very rapidly

D once per year as the Earth goes around the sun



which of the following types of meteoroids is expected to be most common in the solar system?

A irons

B stonys

C stony-irons

D carbonaceous chondrites



perhaps the most interesting and fascinating material to be found inside rocks which have come to us from outer space is

A radioactive material

B pure iron

C carbon

D amino acids



which solar system objects are observed outside the ecliptic plane?

A asteroids

B comets

C Jovian planets

D none of the above



the ion tail of a comet:

A points almost directly toward the sun.

B trails behind the comet in the direction from which it came.

C points away from the sun but lags because of the speed of the comet.

D points nearly directly away from the sun.



comets

A have tails which trail behind the head of the comet, as a dot's tail does

B can have two tails

C are thought to originate in the sun

D never return after one passage



consider the general physical properties of the small bodies in the solar system. which two are the most similar?

A comets and asteroids.

B comets and meteoroids.

C comets and meteorites.

D asteroids and meteoroids.



opposition occurs when the moon is

A on the opposite side of the Earth as seen from the sun

B on the same side of the Earth as seen from the sun

C both (a) and (b)

D none of these



one theory suggests that the bodies in the Oort cloud formed

A near the present orbits of the terrestrial planets.

B near the present orbits of the Jovian planets.

C at high temperatures.

D from silicate materials.



what are the Apollo asteroids?

A the Apollos orbit between Jupiter and Saturn.

B the Apollos are a specific group of asteroids between the kirkwood gaps.

C the Apollos are asteroids that cross the orbit of the Earth.

D the Apollos orbit between the sun and Mercury.



the fact that volatile gasses are present in comets today tells us that the interiors of comets have been

A subjected to high temperatures

B hot in the past, but are cool today

C cold in the past, but hot today

D cold in the past and still cold today



the orbits of long-period comets are

A in the ecliptic

B randomly oriented with respect to the ecliptic

C similar to Pluto's orbit

D the same as the orbits of short-period comets, except they move slower



the major factor which might have kept the material which formed the asteroids from not forming a planet was probably tidal effects from

A the sun

B Mars

C Jupiter

D Saturn



a shooting star is

A a hot spot in our atmosphere caused by an intensification of the Earth's magnetic field

B a piece of "rock" burning up as it travels through our atmosphere

C a very bright comet as it streaks close to the sun

D a temporary planet in our solar system.



small, mostly frozen gaseous bodies which orbit the sun are

A meteors

B asteroids

C planets

D comets



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