Pentathlon Science Section 3
The surface temperature of Triton is the coldest observed in the Solar System, about ________°C (-391°F).
-235
All of the planets together represent only _____ the mass and ___ the volume of the Sun (#)
0.001, 0.3
The total mass of these asteroids is estimated to be less than ________ percent that of Earth
0.01
The Earth's atmosphere contains ___ percent argon, carbon dioxide, and other gases.
1
At sea level the atmosphere presses down with a pressure of 101.3 kPa (14.7 pounds per square inch), which is known as _____________ of pressure.
1 atmosphere
What are the three conditions that defines a planet?
1) The body orbits the Sun. 2) The body has sufficient mass to be nearly round. 3) The body clears the region around its own orbit(in other words, the body does not share its orbital region with other bodies of similar size, except its own satellites).
At sea level, the air pressure on Earth is about __________ millibars.
1,013
The largest mare of this type, Mare Imbrium, the Sea of Showers, is about _______________ across.
1,100 km (700 miles)
Deimos completes a circuit in ______ days.
1.3
The Moon's equatorial diameter is about _______ the equatorial diameter of Earth (fraction)
1/4
Additionally, objects (on the Moon) accelerate downward at ____ the rate they would on Earth (fraction)
1/6
The Moon's surface gravity is about ____ that of Earth due to its smaller mass and size. (fraction)
1/6
The Moon's mass, which can be determined from the forces the Moon exerts on spacecraft, is 7.35 × 1022 kg, or _______ that of Earth (fraction)
1/81
On the side further from the Sun, the magnetosphere extends like a tail to a distance of about ____________ Earth radii.
10 to 1,000
The U.S. spacecraft Dawn entered a ____-month orbit around Vesta in July 2011 and began orbiting Ceres in March 2015.
14
The surface pressure (of Triton) is about _____ microbars, or 1/70,000 that of Earth
14
Venus was the first planet beyond Earth to be visited by a spacecraft, the Mariner 2 in _______
1962
Venus was first planet to be successfully landed on, by Venera 7 in _______
1970
The Jovian system, consisting of Jupiter and its moons, was explored by the U.S. robotic probes Voyager 1 and 2 in _____
1979
Voyager 1 in ______ and Voyager 2 in _______ sent back 33,000 images of the Saturnian system as they flew by.
1981, 1982
The total surface area of our planet is about 5.10 ×108 km2 ( ______________ square miles)
199 million
the surface air pressure (of Mercury) is barely _______________ of Earth's at sea level
2 trillionths
The mantle extends about __________________ miles below the crust
2,900 km (1,800)
The continents separate slowly, at a rate of about _________ per year
2.5 cm (1 inch)
About _____________ years ago, all of the world's continents were joined in one huge supercontinent
200 million
The NASA spacecraft Messenger was launched in _________ to investigate key scientific questions and fully map the planet from orbit in2011, after three flybys in 2008 and 2009
2004
In _______, following extensive discussion, the International Astronomical Union (IAU) formally introduced the designation of dwarf planet
2006
What year was Pluto reclassified from a planet to a dwarf planet?
2006
The Earth's atmosphere contains ____ percent oxygen
21
After about ______ hours on the Moon, they ascended from the surface to rejoin Collins in the orbiter
21 ½
The largest, flat-floored craters, such as Clavius, are nearly ___________ across.
240 km (150 miles)
Its (ozone) concentration is greatest at an altitude of around _____ km
25
The Barringer Meteor Crater, near Winslow, Arizona, is 1.2 km in diameter and 0.2 km deep, and resulted from a meteorite impact about __________ years ago.
25,000
The Moon rotates on its axis every ______ days
27.3
Saturn has an orbital period of _______ Earth years
29.5
The Moon's equatorial diameter is _______________
3,476 km (2,160 miles)
How thick is the core?
3,500 km (2,170 miles)
The Moon's average density is 3.34 g/cm3 , or roughly ____ that of Earth (fraction)
3/5
Recent calculations suggest that the object in question was a rocky meteoroid about ____ meters across
30
It (the Great Red Spot) has been observed for over _______ years at varying sizes, brightness, and color
300
What is the crust's average thickness?
35 km (22 miles)
Hellas, the largest impact crater in the Solar System, is about __________ years old
4 billion
According to the solar nebular model, the solar system formed out of a rotating interstellar cloud about _____________ years ago.
4.6 billion
The magnetic poles drift some ______________ a year
40 km (25 miles)
Some _____________ asteroids have been observed
400,000
The rate that continents separate a year translates to an overall motion of __________ in 200 million years.
5,000 km (3,000 miles)
The total mass of Earth's atmosphere is about ____________ tons, or about one-millionth the mass of the planet itself
5,000 trillion
The core is most likely made of dense iron and nickel at a temperature of about _________ K.
6,400
Charon orbits Pluto in ___________ days
6.387
Saturn has at least ____ confirmed and several suspected moons
60
There are at least _____ confirmed moons orbiting Jupiter
63
Air pressure on Mars is a fraction of that on Earth, at only about ___ or ___ millibars.
7 or 8
Phobos orbits Mars every ______ hours
7.7
Over ____ percent of Earth's surface is covered by water
70
Armstrong's first step on the Moon was witnessed by about ___________ people, about one-fifth the population of Earth.
723 million
Today, Earth's atmosphere contains about ____ percent nitrogen
78
Highlands contain light-colored igneous rocks and cover about _____ percent of the Moon's surface
80
Atmospheric pressure is ___ times greater than that on Earth, and lightning and thunderstorms occur frequently
90
Winds on Uranus blow at speeds of ______ to _____ miles per hour
90, 360
Saturn's mass is _____ times that of Earth, while its volume is ______ times that of Earth.
95, 844
The angle between its (Uranus) axis and the pole of its orbit is a unique ___°
98
NASA Magellan orbiter, which mapped _____ percent of the planet and also studied its atmosphere and ____________
99, interior
________ has the brightest and possibly youngest surface (of Uranus' large moons)
Ariel
Mars' moons were discovered in 1877 by American astronomer ____________
Asaph Hall
_______________, or minor planets, are irregularly shaped bodies of rock and/or metal
Asteroids
The NASA Curiosity rover arrived at Mars' Gale Crater in ______________ to search for signs of ancient microbial life and assess the conditions for future human exploration
August 2012
What happened in the 1967 Apollo 1 accident?
Cabin fire took the lives of crewmembers Virgil "Gus" Grissom, Ed White, and Roger Chaffee during a pre-launch test
The largest crater on Mercury, ________________, is 1,300 km across
Caloris Basin
____________ is 950 km (590 miles) across and was classified as a dwarf planet along with Pluto and Eris in 2006
Ceres
Pluto's moon _________ is about half its size
Charon
The huge _________ crater buried under the Yucatan Peninsula in Mexico is the postulated impact site for a meteoric event that could have caused the catastrophic disruption of the biosphere and mass extinction of dinosaurs, many plants, and other animal species 65 million years ago. METEOROIDS
Chicxulub
Scattered rocks, powdery dirt, sand dunes, and distant low hills came into view on _______________ ("Plains of Gold").
Chryse Planitia
Following its discovery in 1930 by American astronomer ___________ ____________, Pluto was designated as the ninth planet in the Solar System
Clyde Tombaugh
The hydrogen cloud surrounding the nucleus of _________ __________ at its 1986 grew to several hundred thousand kilometers in diameter
Comet Halley
____________ are small, icy celestial objects that produce a distinctive tail as they pass near the Sun
Comets
In _______________, Apollo 8 became the first manned mission to orbit the Moon and return
December 1968
In 2001, the U.S. ______________ probe collected high-resolution photographs of comet 19P/Borrelly
Deep Space 1
The Moon has a near side that always faces ________, and a far side
Earth
The U.S. robotic probe NEAR (Near Earth Asteroid Rendezvous) Shoemaker, launched in 1996, orbited the asteroid _____ for over a year before successfully landing on its surface on February 12, 2001
Eros
Apollo 1, suffered a tragic accident on __________________
February 21, 1967
The most widely accepted description of a typical comet is the "dirty snowball" model, proposed by American astronomer ___________ __________ in 1950
Fred Whipple
The four largest moons—Io, Europa, Ganymede, and Callisto—are collectively known as the _______________ ________
Galilean moons
The U.S. robotic probe __________ sent the first closeup of an asteroid, 951 Gaspra, in 1991 and of a small satellite, Dactyl, orbiting 243 Ida, in1993
Galileo
The Kuiper Belt was named for Dutch-American astronomer _________ _________, who predicted the existence of KBOs in 1951
Gerard Kuiper
In 1986, the European Space Agency's ________ spacecraft approached Halley's Comet at a distance of 596 km, becoming the first spacecraft to make closeup observations of a comet
Giotto
The largest known asteroid, named Ceres, was discovered in 1801 by Sicilian astronomer ___________ _________
Giuseppi Piazzi
_________________ changes may have transformed Mars from a running water environment into the cold, dry world it is today.
Global-scale climate
_________ keeps the atmosphere bound to Earth
Gravity
Jupiter's famous _________________ is a colossal atmospheric storm, about 1.3 times the diameter of Earth
Great Red Spot
The lowest point on Mars, 7 km (4 miles) below the mean surface, is the bottom of the circular _____________ basin.
Hellas Planitia
The largest meteorite ever found, the _________ _________, weighs an estimated 66tons and still lies in Namibia in Africa where it landed
Hoba West
In 2004, the U.S./European spacecraft Cassini, using gravity assists from Venus, Earth, and Jupiter, neared Saturn and ejected a probe, called _____________.
Huygens
Spirit and Opportunity, which landed on opposite sides of Mars' equatorial region in _____________
January 2004
In 1846, astronomer ___________ _______ at the Berlin Observatory in Germany directed his telescope to the predicted location and discovered Neptune
Johann Galle
What is the heaviest and largest planet?
Jupiter
The Apollo 11 mission successfully fulfilled President _______________ goal of achieving the first Moon landing by the end of the 1960s
Kennedy's
The _____________ _________ is a vast region of the Solar System beyond Neptune containing icy bodies and larger masses known as __________ _______ objects (KBOs)
Kuiper Belt
Armstrong and Aldrin transferred to the ________ _________ (named Eagle) and descended to the surface while Collins remained in orbit.
Lunar Module
More American, Russian, and European probes have explored _______ than any other planet.
Mars
The next Mars mission, known as ___________ , is a rover based on Curiosity's design.
Mars 2020
What is the lightest and smallest planet?
Mercury
___________ is the smallest planet in the Solar System and the one closest to the Sun
Mercury
What are the eight planets of our solar system in order?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune
_____________ stands for MErcury Surface Space ENvironment GEochemistry and Ranging Mission,
Messenger
______________, or "shooting stars," are streaks of light created by meteoroids that plunge through Earth's atmosphere at speeds up to 72 km (45 miles) per second
Meteors
Eris, in 2003, and its moon Dysnomia, in 2005, were discovered by U.S. astronomers ____________ _________ and his team
Michael Brown
__________________ is also responsible for earthquakes, volcanic activity, and the formation of mountain ranges
Movement of the plates
The highest point on the Earth's surface is ____________
Mt. Everest
In 2006, the U.S. space probe _______ _________ launched with the mission of studying the Pluto system.
New Horizons
Pluto also has several smaller moons including _____, named for the goddess of darkness and night, and ___________, named for a multi-headed monster that guarded the underworld
Nix, Hydra
The next crewed spaceflight mission, Apollo 7, launched on ________________
October 11, 1968
Mars has huge shield volcanoes, including _______________
Olympus Mons
____________ is a molecule made up of three oxygen atoms, which is formed in the atmosphere when ultraviolet radiation interacts with oxygen molecules.
Ozone
What was the huge supercontinent called?
Pangaea
In July 1997, the U.S. ___________ lander and ____________ rover explored the Martian surface.
Pathfinder, Sojourner
Mars has two small moons, named ____________ and _____________
Phobos, Deimos
In 2008, NASA's ____________ _______ lander discovered subterranean ice and chemicals that are important for life, and minerals that are created in liquid water.
Phoenix Mars
What do the object that surround the Sun include?
Planets, dwarf planets, moons, asteroids (also called minor planets), comets, Kuiper Belt objects, and interplanetary dust and gas.
Nine years later, on July 14, 2015, New Horizons became the first spacecraft to explore __________ during a historic flyby 12,500 km from the surface of the dwarf planet
Pluto
What moon is the largest of Neptune's small moons?
Proteus
_______, the largest of these (Uranus' smaller moons), is 155 km (96 miles) in diameter
Puck
More recently, the European space probe ____________ successfully landed on the comet67P/Churyumov-Gerasimenko in August 2014.
Rosetta
The Eagle successfully landed in a mare basin named the ______________________
Sea of Tranquility
Although expected to last no more than a few weeks, both (rovers) remained in operation until _______________
September 1997
The ____________ ______________ is made up of the Sun and all objects gravitationally bound to it
Solar System
___________ , Phobos' largest crater, measures practically 10 km (6miles) across
Stickney
In 2005, the U.S. Deep Impact probe excavated debris from the interior of the nucleus of comet ________________ which when analyzed was found to contain more dust and less ice than scientists had expected
Tempel 1
______ smaller moons of Uranus were discovered by the Voyager 2 spacecraft
Ten
The first words spoken on the Moon were Armstrong's now famous phrase-
That's one small step for [a] man, one giant leap for mankind."
Saturn's largest moon, _________, has a thick, hazy, orange-colored atmosphere that is mostly nitrogen, with hydrocarbons such as methane
Titan
_________ was the first moon (of Uranus') discovered, in 1787, and ____________ the last, in 1948
Titania, Miranda
_________ is the largest and the most interesting (moon of Neptune's)
Triton
Mars' largest canyon, _______________, is a complex network of rocky valleys extending 5,000 km (3,000 miles) around the equator with an average depth of 6km (4 miles).
Valles Mariner
These particles (from the solar wind) move rapidly within two doughnut-shaped regions in the magnetosphere known as the _________________
Van Allen belts
In the night sky, Jupiter appears brighter than all the stars and all the planets except ____________ .
Venus
The first images of the surface of Mars were provided by the U.S. robot __________________
Viking Lander 1
Uranus was discovered in 1781 by British astronomer ____________ ____________
William Herschel
According to the International Astronomical Union (IAU), what is a planet defined as?
a celestial body that satisfies the three conditions
What does the ozone layer serve as?
a shield from ultraviolet radiation
How long ago was Earth formed?
about 4.6 billion years ago
What is Earth's mass?
about 6 × 10^24 kg
Meteor showers occur when Earth, moving along its orbit around the Sun, crosses a swarm of meteoroids left behind by an _____ comet
active
Saturn, the most distant planet that is visible to the unaided eye, is named for the Roman god of _____________
agriculture
Jupiter is more massive than _____________ and ________ combined
all the other planets, their moons
the same side of the Moon faces Earth at __________
all times
Atmospheric pressure decreases exponentially with increasing ____________
altitude
Where were the oldest rocks discovered?
amid the remote lakes and tundra of northwest Canada
The Moon's size can be determined from measurements of its _________ _____________ and its distance from Earth
angular diameter
How old are the oldest rocks discovered?
around 4 billion years old
Most asteroids orbit the Sun in the __________ _______, a region between the orbits of Mars and Jupiter
asteroid belt
Earth is surrounded by an ____________ that extends several hundred kilometers out into space
atmosphere
Helium, sodium, hydrogen, and oxygen have been detected in Mercury's ____________
atmosphere
Venus' _______________ consists of about 97 percent carbon dioxide and 1 to 3 percent nitrogen with traces of water vapor, helium, neon, argon, sulfur compounds, and oxygen
atmosphere
The millibar is another common unit of ____________ pressure
atmospheric
The presence of liquid water on Titan could indicate the possibility of _______________ processes despite the moon's otherwise harsh conditions.
biological
One of the most recent documented meteoric events occurred in central Siberia on June 30,1908, leaving a ___________ __________ at ground level but no well-formed crater
blasted depression
Meteors occur but are not visible during the daytime because the sky is too __________
bright
Venus is visible as a _________ _______-like object in the night sky
bright star
Europa, about the same size and density as our Moon, is the ________ Galilean moon
brightest
Uranus is tipped on its side and surrounded by a system of narrow rings, making it resemble a giant _______ _____
bull's eye
Meteoroids smaller than about a meter in diameter generally _________ up in Earth's atmosphere
burn
How do geologists indirectly determine the composition of our planet?
by observing how seismic waves are transmitted through the Earth and along its surface
Shield volcanoes often contain a ____________, or hollow indentation, at the summit
caldera
Very dark C-type asteroids, so called because they contain a large amount of _____________, are very common in the outer asteroid belt
carbon
Mars' atmosphere is made up of about 95 percent ___________ _________, with 2 to 3 percent nitrogen, 1 to 2percent argon, and 0.1 to 0.4 percent oxygen, with traces of water vapor and other gases.
carbon dioxide
What would CSM eventually do?
carry astronauts to the Moon and back
Saturn's magnetic field drags along ____________ _________, which circle the planet as it rotates
charged particles
Huygens collected information about the ___________ ____________ of the atmosphere and clouds and snapped pictures for two and a half hours during its descent
chemical composition
Viking 1 and 2 sent back over 4500 pictures, 3million weather reports, and data from ______________ and ______________ tests (from Mars).
chemical, biological
Venus is the planet with the _________ ____________ to Earth.
closest approach
Unlike Uranus' relatively featureless atmosphere, however, Neptune's atmosphere contains multiple long __________ _________ and several large spots
cloud bands
Neptune has a thick hydrogen, helium, and methane _________ ________ that gives it a bright blue appearance
cloud cover
Nitrogen ice particles may form thin _________
clouds
The (Uranus') atmosphere has __________ running east to west like those of Jupiter and Saturn
clouds
Venus shines brilliantly because it is surrounded by a highly reflective layer of _________, about 20 km thick.
clouds
KBOs are likely leftover materials from the formation of the Solar System that never __________ into planets
coalesced
Astronomers hypothesize that Uranus may have suffered a ______________ with a planet-sized body that knocked it over early in its history
collision
Features that look like the remains of very large basins may be the result of __________ with large chunks of rock and metal
collisions
Neptune's small moons and rings are most likely fragments of larger moons shattered in _______________.
collisions
A comet consists of a head with a star like core called the nucleus, surrounded by a glowing halo called the _______ and trailed by a long semi-transparent tail
coma
Increasing temperature and pressure (on Jupiter) __________ the gas into a liquid and an Earth-size solid core
compress
Mars likely has a mantle that is ________ and _________ than Earth's.
cooler, thicker
The largest volcanic structures on Venus are huge, roughly circular regions known as __________
coronae
The Great Red Spot rotates _______________ and also moves around the planet.
counterclockwise
Except for Enceladus, all of Saturn's moons are heavily __________
cratered
Their (Umbriel and Oberon's) surfaces are heavily ___________ and old, indicating little past geologic activity
cratered
The smallest (craters) are known as __________
craterlets
The Martian surface is lined with canyons and pockmarked by ________
craters
The Moon's surface is pitted with bowl-shaped indentations called _________
craters
The _______ is the thin, outermost, solid layer
crust
As the comet continues moving, a dust tail ____________ behind it.
curves
Umbriel and Oberon have the __________ appearance
darkest
Voyager 2 detected haze around the sunlit south pole (of Uranus) and large amounts of ultraviolet light, called __________, radiated from the sunlight hemisphere
dayglow
Saturn has the lowest average __________ of all the planets in the Solar System
density
Eris, for the Greek goddess of _________ and strife, and Dysnomia, for Eris's daughter, spirit of ____________________
discord, lawlessness
Around 1845, astronomers John Adams of England and Urbain Le Verrier of France independently observed that Uranus did not follow the orbit Newton's law of gravity predicted it should and hypothesized that its motion was being __________ by an undiscovered planet's gravity.
disturbed
The Apollo 9 mission in early 1969 tested the _________ capabilities of the CSM
docking
The Apollo 10 mission served as a "_______ ___________" for the Moon landing
dress rehearsal
Mars' crust is about 50 km (30 miles) thick and does not ________ as Earth's continents do.
drift
Collisions between the ice chunks may create the fine ________
dust
Winds up to 120 km (75 miles) per hour blow light-colored _____
dust
a _________ ________ orbits the Sun and is massive enough to be nearly round but does not clear the region around its orbit.
dwarf planet
What are some smaller bodies that make up our Solar System?
dwarf planets, comets, and asteroids
Although Neptune receives only 3 percent as much sunlight as Jupiter, it has a __________ atmosphere with many ________ systems
dynamic, storm
Both Pluto and Eris have very ____________ (i.e., highly elliptical) orbits
eccentric
Our Solar System is made up of _____ planets
eight
Some younger craters, such as the 18-km (11-mile) wide crater Yuty, are surrounded by multiple layers of _____________ material that form an apparent splash-like pattern
ejected
What did the Apollo 10 mission practice?
entering the 15.6 km approach orbit from which a landing mission would begin descent
A thick layer of water ice and frozen methane, nitrogen, and carbon monoxide, polar caps, and large, dark spots near the ________ cover Pluto's surface, and a layer of frozen methane appears to cover the _______ of Eris
equator, surface
Six small, dark moons discovered by Voyager 2 and five larger moons orbit close to Neptune's _____________ _________
equatorial plane
Nearly 100 craters larger than 0.1 km in diameter can be found on Earth's surface, although most of these have been significantly worn away by _________
erosion
Earth's surface is constantly changing due to _______ and _______________ ___________
erosion, geological activity
Cassini also observed mountains and an ________________ _______, which suggests that methane and ethane form clouds, rain out into pools and rivers, and evaporate into clouds again.
ethane lake
The ___________ asteroids are likely fragments resulting from collisions
fainter
Titania has huge __________ systems and canyons that provide evidence of past geologic activity.
fault
Miranda has huge _________ _________ as deep as 20 km (12 miles), terraced layers, a chevron feature, large relief mountains, ridges, and rolling plains
fault canyons
On July 16, 1969, Neil Armstrong, Michael Collins, and Edwin "Buzz" Aldrin launched from Kennedy Space Center on the Apollo 11 mission that resulted in the ___________.
first Moon landing
Uranus has _______ large moons and at least _____ small moons
five, 27
On Mars, there is ample evidence of ancient catastrophic _____________.
flooding
These rovers (Spirit and Opportunity) discovered evidence of past _________ _________ in rocks, minerals, and geologic landforms
flowing water
Tides are daily ___________ in ocean level on Earth
fluctuations
On the side closer to the Sun, the magnetosphere extends out to ________ times Earth's radius
four
The Voyager 2 spacecraft discovered ______ rings circling Neptune, which may consist of ice particles
four
Mars is in many ways the next _________ in space exploration
frontier
Triton's large south polar cap is slightly pink and is composed of _________ nitrogen and methane.
frozen
As a comet nucleus approaches to within a few hundred million kilometers of the Sun, its ice begins to melt and boil off into a ______, along with dust particles
gas
Jupiter is classified as a _____ _________, which is a giant planet composed primarily of hydrogen and helium
gas giant
A comet's characteristic tail forms from the same ________ that makeup the coma.
gases
(On Mars) Thin layers of ice and dust hundreds of kilometers long have been laid down at the north and south poles by _______________ in alternating seasons.
global dust storms
Ganymede has dark, probably ancient, areas with many craters and lighter, younger terrain that is grooved, suggesting ___________ __________ activity
global tectonic
These (small) moons (that orbit Neptune) are named for water _______ and ____________ in ancient mythology
gods, nymphs
These particles may be remnants of a moon that was broken by a high-velocity impact or torn apart by _________________ effects
gravitational
Tides are caused by the fact that the Moon's ______________________ _____________ is slightly greater on the side of Earth that faces the Moon
gravitational attraction
This mixture of different terrain types on older and younger surfaces suggests that Miranda has been affected by tectonic activity, violent impacts, and tidal heating caused by Uranus's __________________ __________
gravitational pull
Surface temperatures on Venus reach 482°C (900°F) due to the ______________ effect
greenhouse
Increasing concentrations of carbon dioxide and other compounds released by burning coal and oil contributes to a ________________ effect in which thermal energy from the Sun passes through our atmosphere but then becomes ___________
greenhouse, trapped
Uranus' two largest moons, Titania and Oberon, are about _____ the size of Earth's moon
half
Although it was almost named for King George III, Uranus was ultimately named traditionally for the Greek god of the ___________
heavens
Most scientists view the additional greenhouse effect due to _________ ____________ as a leading cause of global temperature rises over the course of the last several decades.
human sources
Earth, the third planet from the Sun, is ___________ home
humanity's
Uranus' atmosphere is composed of mostly _____________ and about 15 percent helium, with smaller amounts of methane and other hydrocarbons
hydrogen
Jupiter has a thick atmosphere composed primarily of ______________ and ____________
hydrogen, helium
Recent infrared measurements of Triton's crust indicated the presence of nitrogen, carbon monoxide, and carbon dioxide, all in ____ form
ice
Saturn's other large moons appear to be mainly _______.
ice
There is evidence of _____ on the surfaces of Europa, Ganymede, and Callisto
ice
Voyager 2 found that the moons are dark gray ice-rock conglomerates, composed of about 50 percent ____, 20 percent carbon and nitrogen-based materials, and 30 percent rock.
ice
Geyser-like jets near the south pole of Enceladus spray ________ __________ far out, perhaps providing evidence of liquid water beneath its surface.
ice crystals
High radar reflectivity could indicate the presence of _____ __________ within craters near Mercury's poles, where temperatures average about -148°C (-235°F).
ice deposits
Neptune, along with Uranus, is classified as an ____ _______, which is a type of gas giant composed mainly of gaseous elements heavier than hydrogen and helium surrounding a rocky core
ice giant
Saturn's rings consist of billions of ____ ____________ that resemble icy snowballs or ice-frosted rocks
ice particles
These rings (around Uranus) are very dark and are composed mainly of large _____ _________
icy chunks
Iapetus has _____ and _________ material on opposite sides
icy, dark
The landers (on Venus) found a very __________ world, and each one stopped working within two hours due to the severe conditions.
inhospitable
More recently, the Mars InSight lander launched in May 2018 and touched down in November of that year, with a mission of studying Mars' __________________________.
interior and seismic activity
Active geyser-like eruptions spray _____________ nitrogen gas and dark dust particles
invisible
the atmosphere is kept partly __________ by solar ultraviolet radiation
ionized
Ultraviolet radiation tears the gases apart into molecular fragments and _________
ions
Earth's magnetic field is generated by its liquid __________ core
iron-nickel
Intense ______________ may have darkened any methane trapped in the icy surfaces
irradiation
The amount of sunlight that asteroids reflect to Earth varies and repeats after several hours, which indicates that they have ____________ shapes and are ___________
irregular, rotating
Jupiter, the largest planet in the Solar System, is named for the _____________ in Roman mythology
king of the gods
What was the goal of the Apollo program?
landing the first men on the Moon
The Moon is unusually _______ for a satellite, in comparison to its parent planet
large
Ganymede is the ________ moon in the solar system
largest
Large, smooth areas resembling the Moon's maria suggest that extensive ___________________ occurred in Mercury's past
lava flooding
The Apollo 9 mission demonstrated the _____ __________ system that would sustain astronauts on the Moon.
life support
Planets do not generate their own _____ as stars do
light
What is the crust mainly composed of?
lightweight rocks such as granite and basalt
The effect is greatest in Earth's oceans, because _______ can most easily move around on our planet's surface
liquid
Mars does not have _______________ today.
liquid surface water
Data from Cassini in 2012 suggests that __________ __________ may exist underneath the icy exterior (of Titan).
liquid water
Comets were named for their appearance— both the Greek word kometes and the Latin word cometa mean "____________."
long-haired
The planet Venus, named for the Roman goddess of _______ and _____________, is the next-furthest planet from the Sun.
love and beauty
Little is known about the exact interior of Pluto and Eris, but their _____ __________ indicate that both must be made of ice and rock
low densities
The brighter areas of the Moon are called the _____ ___________.
lunar highlands
Armstrong and Aldrin planted an American flag, took photographs, and collected samples of _______ ______
lunar soil
Earth has a ___________ ________, or region of magnetic forces, that affects compass needles
magnetic field
The Earth's ________ _______ are located at about 83°N latitude, 115°W longitude in northeast Canada—1,300 km (800 miles) from the geographic North Pole—and at about 65°S, 138°Ein Antarctica.
magnetic poles
Linear bands of highly _______________ material appear in some of the oldest crust (on Mars).
magnetized
Earth's _____________________, the region around the planet where its magnetic field is influential, extends outward into space.
magnetosphere
Saturn's ____________________ is about one third the size of Jupiter's
magnetosphere
The ________ is the layer below the crust
mantle
He called these regions (he thought were oceans) ________ (singular _____), meaning "seas."
maria, mare
Between 50 and 80 km from Earth's surface lies the ________________
mesosphere
Very bright M-type asteroids are ____________
metallic
On several predictable dates every year you may see meteors rain down from one part of the sky. This type of display is called a ___________ ___________
meteor shower
When a piece of stone or metal from outer space lands on Earth, it is called a _____________
meteorite
Countless bits and pieces of rock and dust, called ______________, populate the inner Solar System
meteoroids
Most craters were formed by high-speed _____________ striking the surface of the Moon
meteoroids
Uranus' blue appearance is caused by the ____________ in its atmosphere
methane
These (ice) particles can range in size from ___________ to _________
micrometers, meters
In the past, Mars must have had a _____________ core and magnetic and geologic activity
molten iron
How deep is the Marianas Trench?
more than 11 km (36,000 feet) below the Pacific Ocean's surface
Saturn is a huge _____________ gas ball of mostly hydrogen and helium, making it a gas giant like Jupiter
multilayered
Uranus remained largely a ____________ until 1986, when the Voyager 2 spacecraft flew within 81,500 km (50,600 miles) of its cloud tops
mystery
Uranus has ___________ ______ that are distinctly different from those of Jupiter and Saturn
narrow rings
The bright asteroids are likely clumps of matter that condensed from the original solar ________ , but never became massive enough to form a large planet
nebula
The explosion, estimated to have been equal in energy to a 10-megaton ___________ __________, was heard hundreds of kilometers away and produced measurable increases in atmospheric dust levels all across the Northern Hemisphere
nuclear detonation
When a comet is far out in the Solar System it consists of only an irregularly shaped __________ composed of mostly ice and other frozen gases (the "snow") loosely mixed with stony or metallic solids (the "dirt").
nucleus
When Galileo made observations of the Moon's surface through his telescope in 1609, he mistakenly thought the large, relatively smooth dark areas he saw were __________
oceans
They (lunar highlands) are higher, more rugged, ________ _________ than the maria
older regions
Callisto's surface appears ________
oldest
Hyperion appears to be the __________ (of Saturn's moons)
oldest
Beneath Venus' thick clouds, rocks and soil have an ____________ appearance, whereas in direct sunlight on Earth they would appear __________
orange, gray
Moon's rotational period about its axis equals its __________ period around Earth
orbital
Most planets (except for Venus and Uranus) rotate in the same direction as the overall ____________ motion
orbital
Mercury has the greatest ________________ of all the planets
orbital speed
Meteor showers are usually named for the constellation where they seem to __________
originate
The surface of Mercury has many craters, making it similar in appearance to _____________
our Moon
These particles expand _______ around the nucleus for thousands of kilometers, forming the coma
outward
Sun is always directly _____________ on its (Mercury's) equator
overhead
Within the stratosphere lies the ____________ _________, where atmospheric oxygen, ozone, and nitrogen absorb incoming ultraviolet radiation from the Sun.
ozone layer
Pluto moved inside Neptune's orbit in 1980, reached ___________ (closest approach to the Sun) in 1989, and crossed outbound toward _________ (furthest distance from the Sun) in 1999
perihelion, aphelion
Water that once flowed freely on Mars may now be locked in the polar ice caps and under the surface in the form of _____________
permafrost
The Martian sky is colored ______ in daytime
pink
The orbits of all of the planets are in nearly the same _______
plane
According to the theory of _______ _______________, continents and ocean floor are embedded in plates, or rock slabs, several thousand miles across
plate tectonics
Trans-Neptunian (beyond Neptune) dwarf planets are also known as __________
plutoids
The north and south __________ regions are alternately exposed to sunlight and darkness as Uranus orbits the Sun.
polar
The composition of Earth's atmosphere has evolved due to what?
processes such as photosynthesis, in which green plants absorb carbon dioxide from the air and release molecular oxygen (O2 )
In order to map the surface, scientists bounce _________ ________ off Venus and analyze the reflections
radar signals
During a meteor shower, all the meteors appear to come from one common point in the sky, called the _________ of the shower
radiant
Some prominent craters, such as Tycho, are surrounded by spoke-like bright streaks called _____
rays
Martian soil is about 45 percent silicon oxide and 19 percent hydrated iron oxide (rust), which provides its distinctive _____ color.
red
Voyager data showed that Triton's surface contains methane ice, which is thought to contribute to its ________ color
reddish
planets appear to shine as a result of ________________ light from the Sun
reflecting
The distance to the Moon has been measured by precisely timing how long it takes a beam of laser light to reach _____________ placed on the lunar surface and return.
reflectors
The larger particles are likely the _________ of moons, asteroids, and comets
remnants
Planets _________, or orbit around, the Sun in the same direction as this original interstellar cloud
revolve
The main rings contain thousands of tiny ___________, which are partly intertwined and kinked by the gravitational forces of small moons that "shepherd" the ring material.
ringlets
Saturn is known for the impressive _________ that encircle it
rings
Phobos and Deimos are small, irregular ______ chunks
rock
The smaller moons are composed of more than half _______ and _____
rock, ice
Titan is made of ______ and _____
rock, ice
Ganymede and Callisto most likely have a _________ core with a water/ice mantle and a crust of rock and ice
rocky
The planets also ______ as they revolve about the Sun
rotate
Winds (on Uranus) blow in the same direction as the planet __________
rotates
Neptune has a magnetic field that is highly tilted, at 47° relative to its _____________ axis
rotational
High-resolution images and 3D maps from measurements by orbital spacecraft show Mars to be a harsh, ___________, and dry planet.
rugged
Mercury's surface is crisscrossed by _________, or cliffs, up to 2 km high and 1,500 km (930 miles) long.
scarps
Apollo 11 was an unparalleled milestone in human _________ and ______________ achievement and reclaimed American dominance in spaceflight capability
scientific, technological
Craters on the Moon are customarily named after famous ________ and __________ such as Copernicus and Plato.
scientists, philosophers
Neptune was named for the Roman god of the _____
sea
As a result, the planet (Mercury) has no _____________, and some sunlight always shines on its poles.
seasons
___________ _________ result from earthquakes and other disturbances
seismic waves
The irregular shapes of Saturn's small moons indicate they are fragments of ______________ larger bodies
shattered
The most common volcanoes on Venus are of the type known as _____________, which have a broad, dome-like appearance resembling a shield.
shield volcanoes
Comets _________ because the gases surrounding them absorb and re-emit light, and the dust particles also reflect light from the Sun.
shine
The energy of the impact (from the meteoroids) vaporizes the meteoroid and sends ____________ through the lunar surface, forming a circular crater with a high rim and often a central peak.
shockwaves
Scarps are believed to have formed when Mercury's interior cooled and ________, thereby compressing the crust
shrank
Moderately bright S-type asteroids contain __________ mixed with metals and are common in the inner belt
silicates
The rest (of the stuff in Saturn's rings) may be material that never collected into a ______ ______.
single moon
On any clear, dark night you can see an average of ______ meteors an hour
six
Over half of this air is packed within the first ______________ above Earth's surface
six km (four miles)
However, the discovery of similarly ________ objects in the late twentieth century called Pluto's planetary status into question.
sized
Phobos has striations and chains of _______ ______.
small craters
Miranda, the _____________ of the five, has the strangest appearance.
smallest
Although Mars' southern hemisphere is mostly cratered and ancient, its northern hemisphere is basically _________ ________
smooth plains
the thick mantle consists mostly of dense silicate rock that is ______ and _________ like taffy.
soft, pliable
Earth's magnetic field traps many energetic, charged particles from the _______ _______
solar wind
Effects of hydrogen ions released by Comet Halley on the _________ _________ were detected as far as 35 million km (21 million miles) from the nucleus
solar wind
The magnetosphere (of Saturn) varies in size during shifts in the intensity of the ___________ ________.
solar wind
The core consists of an outer, molten, metallic layer about 2,100 km (1,300 miles) thick surrounding a _______ _______.
solid center
Wild dust storms swirl out of Mars' ___________ hemisphere in the summer
southern
Asteroids are classified by how they reflect sunlight using ________________________, the accurate determination of magnitudes within specified wavelength regions
spectrophotometry
Mercury was named for the ____________ god in Roman mythology
speedy messenger
Atmospheric drag may cause dust particles to __________ into the planet.
spiral
What are rays?
splash patterns caused by material ejected from the impact.
Multiple theories exist to explain the formation of these "___________" craters.
splosh
Through a telescope, asteroids appear as stars—in fact, the term asteroid actually comes from the Greek for "__________"
star-like
Above the troposphere, extending up to an altitude of 40-50km, lies the ___________________.
stratosphere
Shield volcanoes are built up over long periods of time by _______________ _____________ and lava flows
successive eruptions
Io has bright white spots that are ___________________, and its thin atmosphere is primarily sulfur dioxide gas.
sulfur dioxide frost
The _______ and _______________ compounds and ammonia at various depths give Jupiter its distinctive red, orange, yellow, and brown colors
sulfur, phosphorous
The presence of ________ _______ in these clouds give Venus a yellow appearance
sulfuric acid
Venus is sometimes referred to as the "morning star" and "evening star" for its appearance just before _______ and ________.
sunrise, sunset
The great height of Mars' volcanoes is a consequence of its lower _________ ______________ (about 40 percent that of Earth).
surface gravity
It (the Great Red Spot) is also cooler than ______________ ________, partly because it towers up to 24 km (15 miles) above them.
surrounding clouds
Earth's gravity has locked the Moon into a __________________ _______
synchronous orbit
These ions are ultimately swept millions of kilometers straight back into a gas, or ion, _____
tail
Comet _____ can stream millions of kilometers into space
tails
Uranus was the first planet identified by means of a ________________.
telescope
Mercury is known for its wide _____________ variations
temperature
The various atmospheric regions are distinguished from one another by the behavior of the ________________
temperature
Radar images indicate that the __________ of Venus consists mostly of dry and rocky plains
terrain
What did the Apollo 10 mission set the stage for?
the Apollo 11 mission and the first Moon landing
What is the deepest measured underwater spot?
the Marianas Trench
Although billions of comets likely orbit the Sun far from Earth, they only shine in the sky when they travel near _____________
the Sun
Mars' atmosphere is too thin to effectively shield the surface from what?
the Sun's harmful ultraviolet rays
What did the Apollo 7 mission successfully test?
the command and service module (CSM)
What was the theory of plate tectonics also known as?
the continental drift theory
What is the center layer of the Earth called?
the core
During the Apollo 10 mission, what did they test?
the equipment and procedures for landing on the Moon
What did the success of the Apollo 8 mission demonstrate?
the success of the mission was a powerful demonstration that a Moon landing was within reach
Above about 80 km, in the _________________
thermosphere
A very _______ atmosphere extends approximately 800 km (500 miles) above Triton's surface
thin
Jupiter is encircled by a faint system of _______ _______, made up of dust grains that have been blasted off the inner moons by meteoroids
thin rings
The extreme temperatures cause volatile substances to be released from the surface, which creates a very _______, ____________ atmosphere.
thin, unstable
The two moons Prometheus and Pandora orbit on the inside and outside edge of one of Saturn's _____________ _______
thinnest rings
The Apollo program was the _____ American spaceflight program
third
Neptune has at least _____________ confirmed moons
thirteen
Apollo 10orbited the Moon _____________ times before returning successfully to Earth,
thirty-one
Olympus Mons has an elevation of almost 25 km, _________ times the elevation of Mt. Everest
three
The maria are actually dry lava beds made of basalt, a dark igneous rock, and formed over _______________ years ago when _____________ from the Moon's hot interior flooded huge impact basins.
three billion, molten lava
This difference in the gravitational force is small, only about 3 percent, but it produces a noticeable deformation— a stretching along the line joining Earth to the Moon called a _______ ________
tidal bulge
This force creates _________ ___________ on Io's surface that are up to a hundred times greater than the typical 1 m (3.3 feet) tidal bulges on Earth
tidal bulges
Europa's smooth, icy crust, crisscrossed by long lines, may hide a global ocean of water warmed by _________ _________.
tidal heat
The heat source for Io's volcanoes is due to a "______ ____________" effect
tidal heating
Gravitational effects between the Earth and the Moon result in ________
tides
The Center for Near Earth Object Studies, a division of NASA's Jet Propulsion Laboratories, computes the ___________ of near-Earth objects and tracks their closest approach to our planet.
trajectories
Everything on Earth's surface lies within the _____________, including Mt. Everest
troposphere
The layer of Earth's atmosphere below about 12 km is called the _______________.
troposphere
Manned spaceflights were subsequently suspended (in response to the 1967 Apollo 1 accident) for _______ months
twenty-one
At most coastal locations on Earth, there are _______ low tides and _______ high tides each day.
two
Pluto, about 2,300 km (1,430 miles) in diameter, is ____________ as large and one-sixth as massive as Earth's Moon
two-thirds
From the ragged edge of this polar cap northward, Triton appears darker and redder, possibly as a result of methane ice turning to carbon upon exposure to ____________ __________
ultraviolet radiation
Meteor showers are best seen with your ____________ eye on nights when the Moon is not bright
unaided
Pluto, named for the Greek god of the ____________, was the first KBO to be discovered
underworld
During this time (the months where manned spaceflights were suspended), ___________ test flights of the Saturn V rocket and Lunar Module continued.
unmanned
Unlike Earth, Mercury has a __________ axis of rotation
vertical
Io has active ____________ that spew sulfur-rich materials that color its surface bright orange, red, brown, black, and white.
volcanoes
Mars is the fourth planet from the Sun, named for the Roman god of _____
war
Its (Saturn's) density is even lower than that of _________ , meaning that it could float in water if a large enough sea existed
water
In 2016, Dawn discovered evidence of __________ _______________ on the surface of Ceres
water molecules
Our atmosphere also contains trace amounts of ___________, _______, ______________, _______________________, and ___________________.
water vapor, dust, carbon monoxide, chemical products of industry, and microorganisms
Rocks found on Mars show evidence of ___________ and _________
weathering, erosion
The strongest _______ on any planet can be found on Neptune
winds
