Astronomy Ch. 6-11 Exam 2 (Fullerton College, Liliana Barabas)
What is the Roche limit?
(2.44) the distance at which a moon held together by gravity will be broken apart by the plants gravitational attraction
What are they named after?
Typically named after the constellation where the radiant is located - Perseid meteor shower has its radiant in Perseus
Formation of planetary systems: What is the composition of interstellar clouds?
gas and dust
Mercury: Describe the surface of Mercury
heavily cratered, haas scarps, contains congealed lava flows in many of its older craters and pave much of its surface, similar to the moon
Tides: Define
the deformation of land and water of the earth due to the gravitational forces of the moon acting on every part of the earth
What is the main cause of tides on Earth?
the difference of the moons gravitational attraction on the water of the earth
What is differentiation and what caused the Earth to be differentiated?
the earth has a layered structure. earth was once molten in the past due to collisions and radioactivity. the earth cooling down is causing the layers
Which are older: maria or highlands?
the highlands are older since they are more cratered
What are the main greenhouse gases in Earth's atmosphere?
water, carbon dioxide, methane, nitrous oxide, ozone
How do we know their composition?
we look at their absorption lines to see what they're composed of
Does the Moon always show the Earth the same side?
yes
Does the same side always stay in darkness?
yes
Do we expect Mars to have seasons? Why or why not?
yes because of its similar axial tilt to Earth
Motions: Does the Moon rotate on its axis?
yes, 5 degrees
Does it have seasons? How do we know?
yes, because of its polar ice caps freezing and melting
Does the Sun create tides?
yes, they're about half as strong as the tides caused by the moon
How many low tides and how many high tides occur everyday?
2 high tides and 2 low tides everyday
How long is the period of precession of Earth?
26,000 years
How long is the Moon's rotation period?
27.3 days
Does it have rings or moons?
5 dark rings, 3 narrow and 2 broad and diffuse. 13 moons. triton is the largest and orbits in opposite direction of Neptune's rotation
Atmosphere: composition and origin
78% Nitrogen. 21% Oxygen. Argon, water vapors, carbon dioxide, ozone. volcanoes releasing these gases trapped by solid material or comets impacting the surface of the Earth were vaporized
Neptune: What is its atmosphere composition?
83% hydrogen, 15% helium, 3% methane
What is its atmosphere composed of?
86.1% molecular hydrogen, 13.8% helium. methane, ammonia, water
What is the atmosphere composed of?
95% carbon dioxide, 3% nitrogen
Venus: What is the composition of its atmosphere?
96% carbon dioxide, 3.5% nitrogen, and small amounts of water and other gases
Describe its axial tilt?
98 degree axial tilt. it basically rotates sideways
What makes a "shooting star"?
A meteor compressing the gas in the atmosphere heating it to the point that it glows
Why are volcanoes on Mars so tall?
Because the lower gravity of Mars generates less buoyancy forces on magma rising through the crust, the magma chambers that feed volcanoes on Mars are thought to be deeper and much larger than those on Earth.
List the names of the four Galilean moons
Io, Europa, Ganymede, Callisto
Meteoroids, Meteors, Meteorites: What is a meteoroid, meteor, meteorite?
Meteoroid: chunk of interplanetary debris less than 100 m PRIOR to encountering Earth's atmosphere. Meteorite: bright streak in the sky resulting from interplanetary debris entering the atmosphere. Meteorite: meteoroid that survives passage through atmosphere and lands on earth
Is Pluto the farthest object object from the Sun in the solar system?
No
What are meteor showers?
Occur as the Earth passes through a stream of debris of a comet. Tracing the tracks of meteors in a shower backwards, they appear to come from a common origin, The Radiant.
What is precession?
the change in orientation of the Earth's rotational axis
Where do meteoroids originate?
Probably formed in the solar nebula 4.6 billion years ago. Collisions eject material from different depths with different compositions and temps. most meteorites come from asteroid or comet debris
Does it have rings or moons?
Uranus has 11 rings composed of rock and dust. it has 27 moons probably composed of ice and rock. moons have heavy cratering
Uranus: Why is it so blue?
Uranus is composed of 2% methane giving it it's blue color and same with Neptune
How was the Moon formed?
a collision on earth caused debris to break off and it formed into the moon
How might they have formed?
a large moon may have gotten too close to Saturn and broke apart
What causes the difference between the solar day and sidereal day?
a solar day (24hr) is measured by the sun and a sidereal day(23hr 56min) is measured by the stars and is the true rotational period
What is the difference between a planet and a star?
a star produces its own light due to nuclear fusion and a planet does not do that
What is the Great Red Spot?
a storm that has been observed since at least 1831 and possibly 1665
Describe Jupiter's ring
a thin ring made of tiny particles of rock dust and held in orbit by Jupiter's gravity. solar radiation and collisions with charged particles trapped in Jupiter's magnetic field exert a friction on the ring dust that will cause the dust to drift into the atmosphere. the maintain the ring new dust must be provided from collision fragments
What is the atmospheric pressure on the surface of Mars?
about 1% of that of Earth
Do planets orbit the sun in the same plane and in the same direction?
all planets orbit the sun counterclockwise and nearly in the same plane
Describe the Doppler method
as a star approaches us in its motion around the center of mass, its spectrum will be blue-shifted and as it recedes, the spectrum will be red shifted. this method works best for large planets near their star
What are the Apollo asteroids?
asteroids with elliptical orbits reaching into the inner solar system, some potentially colliding with Mars and Earth
Other planetary systems: How do astronomers detect extrasolar planets?
astronomers can detect planets orbiting other stars by using the Doppler Method, the Transit Method, or Gravitational Lensing Method
Why is Jupiter's magnetic field so strong?
because of its liquid conductive interior and rapid rotation. it's 20,000 times stronger than earth's
What is a shield volcano?
consists of fluid magma chamber from which lava erupts repeatedly through surface layers above. they are partially underground
Motions of the Earth's interior: What causes tectonic plates?
convection in the Earth's core causes tectonic plates
What is Jupiter composed of?
core of rock and iron, then water, them liquid metallic hydrogen, then molecular hydrogen
Jupiter: What is differential rotation?
different parts of the plant have different periods of rotation because they rotate at different rates, yet in the same direction.
Pluto and beyond: Is it a terrestrial, jovian, or dwarf planet? Why?
dwarf planet, it has not cleared the neighborhood around its orbit
What is the Kuiper Belt composed of?
dwarf planets: pluto, haumea, makemake and frozen volatiles (ices) composed of methane, ammonia, and water (comets) and asteroids
Magnetosphere: what factors are responsible for the magnetic field of a planet?
earth has a magnetosphere due to its liquid metallic core and rapid rotation (dynamo effect)
How are aurora produced?
high energy particles are able to leak through the lower magnetosphere and they excite molecules near the magnetic poles causing aurora
How do we know which are older?
highlands have more craters
When will Vega be the North star?
in about 12,000 years
What is the Coriolis Effect?
in the absence of any force an object will move in a curved path over a rotating object. responsible for the spiral pattern of large storms and their direction of rotation.
What are the effects of a magnetosphere of life on Earth?
it shields earth from much of the solar wind (stream of ionized gas that blows outward from the sun)
Why is it so blue?
it's composed of 3% methane
Why is Io volcanically active?
it's volcanically active due to tidal forces exerted by Jupiter. Io's eccentric orbit cause the tides to change in size and heat its interior
Why is Venus' surface temperature higher than Mercury's?
its atmosphere is thicker (100 times of that of Earth's) so it traps more heat
Saturn: What are the rings made of?
made of a swarm of individual bodies. sizes range from centimeters to meters and is mainly water ice and carbon compounds
Surface: What are maria/highlands?
maria: dark, flat, roughly circular, formed as lava seeped into deeper craters and in the early history of the moon. highlands: lighter in color, elevated several km above the maria
Why are terrestrial planets so different: describe the role of mass, radius, internal activity, sunlight, water content and biological processes
mass and radius: affect interior temperatures which effect tectonic activity and atmosphere. sunlight: warmth of planet depends on distance from the sun which effects the makeup of atmospheric gases present. water content: high altitudes of water in Venusian atmosphere is lost due to photodissociation so Venus los most of its water compared to earth because earths water is protected by lower altitudes. biological processes: removes carbon dioxide from the atmosphere. plants break down CO2 so Earth's atmosphere has a high O2 content
Where are asteroids they located?
most are found in the asteroid belt located between 2.1 AU and 3.3 AU between Mars and Jupiter
What is the origin of most of the lunar craters? Explain.
most craters have meteoric origin and some have volcanic origin
Do all planets rotate (spin) in the same direction?
most planets rotate counterclockwise in the same direction. Venus and Uranus rotate clockwise
Where are auroras observed?
near the magnetic poles
Is Saturn the only planet with rings?
no
Is the near side always lit by the sun?
no
Does Venus have a strong magnetic field? Explain Why or why not
no, it doesn't have one because of its slow rotation and and lack of liquid metallic core
Does Mercury have an atmosphere? Why or Why not?
no, its mass is too small and it's too hot
Why do we not expect Mercury to have a strong magnetic field?
only a small portion of its core is still molten and its rotation is too slow. its magnetic field is 100 times weaker than Earth's
Components of the Solar System: Define the term planet and dwarf planet.
planet: an object in orbit around the sun, has a nearly round shape, and has cleared the neighborhood around its orbit. a dwarf planet is the same except it hasn't cleared its orbit
Mars: Name some prominent surface features on Mars
polar ice caps, reddish color due to rust, giant volcanoes, canyon systems, impact craters, crust not broken into tectonic plates
Why is the ozone layer important?
protects life on Earth from harmful ultraviolet rays from the sun
Age: Explain how the age of rocks is determined?
radiometric dating is used. radioactive atoms decay into daughter atoms. the more daughter atoms a rock has relative to its original atoms the older it is.
Motions: How long is the period of rotation/revolution?
revolution: 1 year. rotation: 1 day
What are the effects of tectonic plates?
rifting: volcanoes. subduction: mountain building, earthquakes, some volcanic activity.
Where is it located?
right outside neptunes orbit and continues beyond pluto
Asteroids: What are they?
rocky bodies that revolve around the sun and are smaller than a planet but are larger than meteoroids
The Earth as a Planet: shape, radius, composition, density (define density)
shape: sphere. radius: 6,378 km or 3,986 mi. density: 5.52 g/cm^3.
What are the Trojan asteroids?
share stable orbits along the orbit of Jupiter and are trapped in the Lagrangian points of Jupiter
Describe the solar nebula hypothesis
solar system started as interstellar cloud of dust and gas, it contracted and heated up forming the sun in the center and flattened into a disk, condensation and accretion formed planetesimals, and strong solar wind during the T Tauri phase formed planets, moons, asteroids, meteoroids, comets
What are the Van Allen belts?
some high energy particles leak through the magnetic field and produce and belt of high energy particles around Earth
What are spring tides and neap tides and when do the occur?
spring tides are stronger than average tides that occur when the tides caused bu the sun are added to the tides caused by the moon and these occur at full and new moon. neap tides are weaker than average tides and occur when the tides caused by the sun are subtracted from the tides caused by the moon and these occur at first and third quarter moon
Interior: How is it studied? List the layers of the Earth's Interior.
studied by analyzing the earth's seismic waves. crust: iron and nickel. inner: solid, dense, hot. outer: liquid, dense, hot. mantle: rocky material temp between 300k-3000k. crust: 5-50km and thicker under continents/thinner under oceans
What are its clouds made of?
sulfuric acid droplets with traces of water
Distinguish properties of terrestrial/jovian planets?
terrestrial: close to the sun, closely spaced orbits, small masses, small radii, predominately rocky, solid surface, higher density, slower rotation, weak magnetic field, few moons, no rings. jovian: far from the sun, widely spaced orbits, large masses, large radii, gaseous, no solid surface, low density, faster rotation, strong magnetic field, many rings
What is a terrestrial/jovian planet?
terrestrial: mercury, venus, earth, mars. jovian: jupiter, saturn, uranus, neptune
Atmosphere: why does the Moon have no atmosphere?
the moon's low mass causes it to have a low escape velocity
Who does the Moon have no magnetosphere?
the moons slow rotation and the absence of a liquid metallic core
Define the greenhouse gas effect
the partial trapping of solar radiation by carbon dioxide and water molecules
Describe the transit method
the transit method looks at the dimming of light from the central star and this method only works for systems seen edge on
Why did asteroids not form into planets?
they're gravity isn't strong enough to pull them into a round shape. and they're too close to Jupiter
What is tidal locking?
tidal locking of the moon is when the Earth raises bulges in the moon and it appears 20 times larger
What are TNO's?
trans neptunian objects. any object past neptune that orbits the sun
