astronomy final

How does the internal cooling rate of the four terrestrial planets compare?

1. Mercury 2. Mars 3. Venus 4. Earth Smaller planets cools fas

What are two proposed reasons for Venus's retrograde motion?

1. Scientists have argued that the sun's gravitational pull on the planet's very dense atmosphere could have caused strong atmospheric tides. Such tides, combined with friction between Venus's mantle and core, could have caused the flip in the first place. 2. A large object struck the planet during its formation which causes it to turn complete turn upside down and spin in retrograde.

What are biosignatures and why are they important for determining if there is life elsewhere in the universe?

A biosignature can provide evidence for living organisms outside the Earth and can be directly or indirectly detected by searching for their unique byproducts.

What is the Io plasma torus?

A doughnut-shaped region of energetic heavy ions that follows Io's orbital track

What is the Giant Red Spot?

A giant storm on Jupiter's surface.

What are geothermal vents? Why do scientists believe that there could be life on the moons of Jupiter/Saturn?

A hydrothermal vent is a fissure on the seafloor from which geothermally heated water issues. There could be alien life living in the subsurface oceans and their could be hydrothermal vents.

Why does Saturn's atmosphere have a helium deficit?

A light shower of liquid helium has been falling through Saturn's interior ever since. This helium precipitation is responsible for depleting the outer layers of their helium content. So we can account for the unusually low abundance of helium in Saturn's atmosphere--much of it has rained down to lower levels.

Why do we believe Jupiter's moon Europa may harbor life?

A liquid water subsurface layer.

What is a runaway versus a reverse greenhouse effect? How has the greenhouse effect enabled life to develop and flourish on Earth?

A runaway greenhouse effect is when there is enough of a greenhouse gas in a planet's atmosphere such that the gas blocks thermal radiation from the planet, preventing the planet from cooling and from having liquid water on its surface. The absorbed energy warms the atmosphere and the surface of the Earth. This process maintains the Earth's temperature at around 33 degrees Celsius warmer than it would otherwise be, allowing life on Earth to exist.

When did most of the cratering on the Moon occur?

About 4 billion years ago

What is the cause of the slowing of Earth's rotation rate?

As Earth rotates, the Moon's gravity causes the oceans to seem to rise and fall. (The Sun also does this, but not as much.) There is a little bit of friction between the tides and the turning Earth, causing the rotation to slow down just a little. As Earth slows, it lets the Moon creep away.

Why does Earth's view of Saturn's rings vary over time?

As Saturn goes around the sun, it periodically turns its rings edge-on to Earth—once every 14-to-15 years. Because the rings are so thin, they can actually disappear when viewed through a small telescope.

What impact has the greenhouse effect had on the surface environment of Mars, Earth and Venus?

As a complete contrast to Venus, there is Mars. The Red Planet displays hardly any greenhouse effect. Mars does have some atmospheric carbon dioxide, but almost no atmosphere! The existing atmosphere is so thin that it cannot retain energy from the Sun.

Describe how nebular theory explains why planetary orbits are nearly circular, lie in nearly the same plane, and orbit in the same sense that the sun rotates

As it relates to our own solar system, the nebular theory explains three observable facts. The first is that the planets all rotate in the same direction. The second is that they all orbit within 6 degrees of a common plane. The third is that all the terrestrial planets, which are those within the orbit of the Asteroid Belt, are rocky, while those outside it are gaseous. The theory also explains the existence of the Kuiper Belt -- a region on the fringes of the solar system with a high concentration of comets

How did temperature gradients in solar nebula result differentiation among the planets?

As the early solar nebula formed, it's heat increased with gravitational collapse, and it formed a flattened, spinning disk. This structure and these motions are reflected in the current constituents of the Solar System. The temperature differences will result in the formation of two distinct types of planets.

Why were Martian volcanoes able to grow so large compared to volcanoes on Earth?

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. If a magma body on Mars is to reach close enough to the surface to erupt before solidifying, it must be big.

In terms of orbit and bulk properties, how does Jupiter compare to Earth and the terrestrials? How does Saturn compare?

Compared to Earth's orbit it is 5x larger. Compared to Earth's density it is much less.

What is differential rotation, and how is it observed on Saturn? On Jupiter?

Differential rotation: rotation of a planet is not constant from one location to the other. (Equatorial zones rotate faster on Jupiter, the interior rotates at the same rate as the polar regions).

What has been the primary mechanism for the creation of the large-scale features of Earth's continents and crust?

Drift of crustal plates due to convection in the asthenosphere

If you were standing on the far side of the Moon, which object would you never see?

Earth

What caused the large equatorial lunar bulge?

Earth's past tidal force on the Moon when it was much closer

What is unusual about the magnetic field orientations of Uranus and Neptune?

Earth, Jupiter and Saturn have fields that are oriented within ~10 degrees of the spin axis. Uranus and Neptune, on the other hand, have highly tilted magnetic fields that are strongly offset: ... But Uranus and Neptune have very irregular magnetic fields - with magnetic "equators" which do not even circle the planet.

What natural phenomenon on Earth provides information about its internal structure?

Earthquakes

What does the appearance of cratering tell you about the age of the surface on the moon and on mercury?

Easily the most prominent observable geologic features on the Moon and the other terrestrial planets are impact craters. And to a geologist, craters are useful features, because they allow us to make an assessment of the age of a planetary surface and even the nature of its interior.

What are the basic necessities for life? What are extremophiles?

Extremophiles are organisms that have been discovered on Earth that survive in environments that were once thought not to be able to sustain life. These extreme environments include intense heat, highly acidic environments, extreme pressure and extreme cold.

What is tidal heating?

Gravitational stresses deforming, flexing, and heating a world's structure.

What processes are responsible for the appearance of Jupiter's atmosphere?

Heat from the interior of Jupiter causes circulation patterns in the atmosphere, with warm gas rising and cooling, before sinking back into the depths of the planet. This process is called convection, and it causes the different colored bands in Jupiter's atmosphere.

Why do we see less varied coloration on Saturn compared to Jupiter?

However, because Saturn's clouds are thicker, there are few holes and gaps in the top layer, so we rarely glimpse the more colorful levels below.

What is Jupiter's atmosphere primarily composed of?

Hydrogen

What is Saturn's atmosphere primarily composed of?

Hydrogen

What evidence do we have for liquid water below Europa's surface?

Images from Galileo show what looks like icebergs. Galileo also found what appeared to be the icy equivalent of lava flows on Earth, regions where water apparently "erupted" through the surface and flowed before solidifying.

In light of this, where would you expect terrestrial versus Jovian planets to form in the solar nebula?

Inner solar system bodies are closer to the sun and outer solar system bodies are further from the sun.

Scientists expected Venus to have a large amount of water. However, little detectable water has been found anywhere on Venus, either on its surface or in its atmosphere. What explanation was proposed?

It could be stuck underneath the surface.

How does the mass of Jupiter compare to the mass of all the other planets combined?

It is twice as massive as all other planets combined.

Why are Jupiter and Saturn noticeably oblate (flattened) rather than spherical?

It's rapid rotation.

Why do Jupiter and Saturn have large magnetic fields?

Jupiter has a large, complex, and intense magnetic field that is thought to arise from electrical currents in the rapidly spinning metallic hydrogen interior.

Describe Jupiter's magnetosphere.

Jupiter has a strong magnetic field because it has a fast rotation and a very large volume of metallic hydrogen by which to generate its field. ... One of these is that the charged particles in Jupiter's field come not from the solar wind, but from the volcanic moon Io.

Why has Jupiter retained most of its original atmosphere?

Jupiter retained most of its original atmosphere because it has a very high mass, and because the temperature was not as high as that of the terrestrial planets during their formation

Which region of Jupiter generates its magnetic field?

Jupiter's internal magnetic field is generated by electrical currents in the planet's outer core, which is composed of liquid metallic hydrogen.

What class of objects has been observed lying just beyond the orbit of Neptune and roughly in the plane of the solar system that lends additional credence to the condensation hypothesis for planetary system formation?

Kuiper belt objects

Compare the internal dynamo of Earth and Jupiter. Why does Jupiter have such a strong magnetic field compared to Earth?

Larger, complex and up to ten times the strength of Earth's, Jupiter's magnetic field is thought to arise from electrical currents emanating from a rapidly spinning, metallic hydrogen interior.

The high abundance of iron on the surface of Mars is indicative of what difference between Earth and Mars?

Mars never melted as extensively as Earth.

Why does Mercury have a more complicated orbital synchronicity than the Moon?

Mercury has a more eccentric orbit around the Sun.

What don't Venus and Mercury have large magnetic fields?

Mercury's field is weak because it rotates so slowly. Venus doesn't have an appreciable field because there appears to be little convection in its molten interior.

What other bodies can we see phases on besides the moon?

Mercury, Venus, and Mars

Do rings seem to be common or uncommon in the solar system?

More common.

What is the greenhouse effect? How does the greenhouse effect change the equilibrium temperature of a planet over time?

More greenhouse gases mean a stronger greenhouse effect and a hotter planet. &diams When the greenhouse gas abundance is increased, it takes time for the system to warm to the new equilibrium temperature. During these times, the Earth absorbs slightly more sunlight than it loses heat, which is what allows the warming.

How do we know that the surface rock on the southern hemisphere of Mars is older than the northern hemisphere?

Most of the rest of the southern highlands have only smaller craters, and all of the northern lowlands have very few craters.

Describe Venus's rotation

Most planets also rotate on their axes in an anti-clockwise direction, but Venus rotates clockwise in retrograde rotation once every 243 Earth days—the slowest rotation of any planet. Because its rotation is so slow, Venus is very close to spherical.

Why are planetary scientists puzzled by the strong winds and rapidly changing storm systems on Neptune?

Neptune lies far from the sun and is very cold, so the source of the energy for these atmospheric phenomena is not known. Uranus, closer to the sun but with a similar atmospheric temperature, shows much less activity.

How does Mars's eccentric orbit lead to more variable seasons for one hemisphere? How would the degree of axial tilt affect the seasons?

Our second-nearest planetary neighbor Mars has the highest orbital eccentricity of any world except Pluto. Its distance from the Sun varies between 1.64 and 1.36 AU over the Martian year. This large variation, combined with an axial tilt greater than Earth's gives rise to seasonal changes far greater than we experience even in Antarctica. Around the summer solstice when the Martian north pole is tilted away from the sun, the northern polar cap expands as carbon dioxide in the polar atmosphere freezes. At the other end of the planet the southern polar cap melts, giving CO2 back to the atmosphere. This process reverses half a year later at the winter solstice.

What is parallax versus parallax angle?

Parallax: The apparent displacement of a foreground object relative to the background as the observers location changes. The parallax angle is the angle between the Earth at one time of year, and the Earth six months later, as measured from a nearby star. Astronomers use this angle to find the distance from the Earth to that star.

From our vantage point on Earth explain why we see different phases moon? How can you determine what phase the moon is in?

Phases are the sunlit portion of the moon that is visible from Earth. The Sun lights up different sides of the Moon as it orbits around Earth — it's the fraction of the Moon from which we see reflected sunlight that determines the lunar phase

For any planet in the solar system or beyond, describe the rotational and orbital properties that give rise to seasons?

Planetary seasons are caused by two factors: axial tilt and variable distance from the sun (orbital eccentricity). Earth's orbit is nearly circular and so has little effect on climate. It's our planet's axial tilt that causes almost all seasonal changes. When the north pole is tilted toward the Sun, it's northern summer. Six months later the north pole tilts away from the Sun and we experience northern winter.

Planetesimals were created through what process? Why is dust important for the condensation hypothesis of planet formation?

Planetiesimals were created through accretion. These tiny grains serve as the building blocks of the planets. Dust grains play an important role in the evolution of any gas cloud. These grains act as condensation nuclei, on which accretion of matter occurs.

What is precession? What is the effect of the slow precession of Earth's rotational axis?

Precession is a change in the orientation of the rotational axis of a rotating body. It causes the set of constellations visible on any particular night each year to change over many years.

Why does Europa have so few impact craters?

Recent activity in its icy crust has erased most craters.

How does the cloud structure of Saturn compare to Jupiter?

Saturn's cloud and haze layers are thicker than those on Jupiter because if Saturn's lower gravity, so we usually only see the upper level of the atmosphere even though the same basic features and cloud layers are there.

What is the source of Saturn's excess energy?

Saturn's excess heat is generated by the precipitation of helium into its metallic hydrogen core.

What are the two theories for how Saturn's rings formed? Is there evidence supporting one over the other?

Saturn's rings probably formed when objects like comets, asteroids, or even moons broke up in orbit around Saturn due to Saturn's very strong gravity. The pieces of these objects kept colliding with each other and broke into even smaller pieces. These pieces gradually spread around Saturn to form its rings.

How does the cooling rate of a planet affect the amount of tectonic activity we see today?

Smaller planets cool faster than larger planets because smaller planets have a larger surface area to volume ratio. The stage of cooling of a planet plays an important role in the geologic activity of that planet. Earth, a large planet, is hot and has active volcanos and plate tectonics at its surface.

What event marked the end of planet formation?

Solar wind from the Sun created the heliosphere and swept away the remaining gas and dust from the protoplanetary disc into interstellar space, ending the planetary formation process.

• What do we believe keeps the surface of Venus so young?

Some scientists have suggested that Venus' old impact craters were erased by a global volcanic resurfacing event, a massive catastrophe that left it with no visible impacts craters at all.

Describe the stages of solar system formation.

Step 1: The solar nebular collapses. Step 2: Rotating protostellar disk Step 3: Center of Nebula fusion begins, star is born Step 4: Planeteseimals eventually planets form

Why does the lunar surface have large variation in its temperature?

Temperatures on the moon are very hot in the daytime, about 100 degrees C. ... This wide variation is because Earth's moon has no atmosphere to hold in heat at night or prevent the surface from getting so hot during the day.

What are the radiation belts such as the Van Allen belts, and why do they exist?

The Van Allen belts are a kind of trap for charged particles like protons and electrons. They're held in place by the magnetic field of the Earth, and so they trace the shape of the magnetic field itself.

How are the magnetic fields of Uranus and Neptune generated? How does this differ from other Jovian planets?

The amount of electrically conducting fluid dictates the strength of a planet's magnetic field: more fluid = stronger magnetic field. Both Uranus and Neptune lack metallic hydrogen in their interiors, but are still surrounded by weak magnetic fields.

What is the primary reason there is oxygen on Earth?

The answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen.

Describe Venus's Atmosphere

The atmosphere of Venus is very hot and thick. ... The atmosphere of Venus is made up mainly of carbon dioxide, and thick clouds of sulfuric acid completely cover the planet. The atmosphere traps the small amount of energy from the sun that does reach the surface along with the heat the planet itself releases.

What do the different colors in Jupiter's clouds indicate?

The depth at which the clouds reside within Jupiter's atmosphere

What drives Earth's tectonic activity? What is the cause of tectonic plate motion?

The driving force behind plate tectonics is convection in the mantle. Hot material near the Earth's core rises, and colder mantle rock sinks. ... Hot magma wells up at the ridges, forming new ocean crust and shoving the plates apart.

How do the Galilean moons act as a mini planetary system?

The early Jupiter would have been surrounded by a disk of material. The Galilean moons reflect a mini Solar System because the Galilean moons acts as terrestrial planets while the outer moons acts as Jovian planets.

What determines the equilibrium temperature of a planet?

The equilibrium temperature of a planet is determined by the size, temperature, and distance to its parent star, but not on its own size.

What is escape velocity and how does one determine the escape velocity of a planet?

The escape velocity is the minimum velocity required to leave a planet or moon. For a rocket or other object to leave a planet, it must overcome the pull of gravity. The formula for escape velocity contains a constant, G, which is called the "universal gravitational constant"

Why doesn't the far side of the Moon have any large maria?

The far side barely has any. Further study shows an odd anomaly: The crust on the far side is a lot thicker than it is on the near side. That explains the lack of maria; the thicker crust means it was harder for giant impacts to pierce the crust and get darker basaltic lava bubbling up.

What is gravity? How does the mutual gravitational attraction of two objects depend on their masses? On their distance from each other?

The force that attracts a body toward the center of the earth, or toward any other physical body having mass. The strength of the gravitational force between two objects depends on two factors, mass and distance. the force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. increases, the force of gravity decreases.

What theory do astronomers use to rectify the apparent problem of insufficient time to form Jovian planets?

The gravitational instability theory.

What do the densities of Uranus and Neptune suggest about their rocky cores, in comparison to Jupiter and Saturn?

The ice giants' rocky, icy cores are also proportionally larger than the amount of gas they contain, unlike the gas giants.

What do Uranus and Neptune's atmospheres contain, other than hydrogen and helium?

The interior structures of Uranus and Neptune are very similar: Thick, slushy mantle of water, ammonia & methane ices. Rocky cores about the size of the Earth. Shallow atmospheres of molecular hydrogen (H2), Helium (He) & methane (CH4).

How did dynamic events early in the Moon's history form its major surface features?

The major events in the Moon's history were: (a) accretion of material ejected from Earth after a massive collision with a Mars-sized object, (b) and differentiation with the formation of the lunar crust by crystallization of a magma ocean, (b) intense meteoritic bombardment, (c) extrusion of the mare lavas, and (d) light bombardment.

What is the Roche limit?

The maximum distance from a planet at which planetary rings can exist.

What is synchronous rotation and why are the Earth and Moon in synchronous rotation.

The moon keeps the same face pointing towards the Earth because its rate of spin is tidally locked so that it is synchronized with its rate of revolution (the time needed to complete one orbit). In other words, the moon rotates exactly once every time it circles the Earth.

How does the parallax of a nearby object compare to that of an object farther away?

The nearby object exhibits a larger parallax than the farther object.

Describe how scientists use the idea of the Roche limit to explain how planetary rings are formed and maintained.

The rings of Saturn lie inside Saturn's Roche limit and may be the debris of a demolished moon. The limit was first calculated by the French astronomer douard Roche

What are Saturn's rings made of? Why are the rings so thin?

The rings orbit Saturn just as our Moon goes around the Earth. If our Moon broke apart, the pieces would form a ring around our planet. The collisions between the ring particles are what make the ring system so thin.

What are Aurorae? Explain how interactions between the solar wind, a planet's magnetosphere, and a planet's atmosphere cause the Aurorae

The short answer to how the aurora happens is that energetic electrically charged particles (mostly electrons) accelerate along the magnetic field lines into the upper atmosphere, where they collide with gas atoms, causing the atoms to give off light.

What is the source of Jupiter's excess energy?

The slow escape of gravitational energy released during the planet's formation.

What evidence of volcanic activity is there on Venus?

The surface of Venus is dominated by volcanic features and has more volcanoes than any other planet in the Solar System. It has a surface that is 90% basalt, and about 65% of the planet consists of a mosaic of volcanic lava plains, indicating that volcanism played a major role in shaping its surface.

What factors determine if a planet will be able to retain an atmosphere?

The thickness of a planet's atmosphere depends on the planet's gravity and the temperature of the atmosphere.

What two components are necessary to create a magnetic dynamo within a planet?

There are three requisites for a dynamo to operate: An electrically conductive fluid medium. Kinetic energy provided by planetary rotation. An internal energy source to drive convective motions within the fluid.

What is the primary reason that the Jovian planets contain so much more volatile liquid and gaseous material than the terrestrial planets?

They orbited at sufficiently greater distances from the Sun that these volatile materials were ices and liquids that were easier to accumulate.

What determines the speed of a molecule in an atmosphere?

This distribution of speeds is greatly affected by the temperature of the gas. Hot gases are moving "faster" and cold gases are moving "slower"

Explain why we have tides? If the earth had no moon, how would this affect the tides?

Tides are caused by the gravitational interaction between the Earth and the Moon. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Scientists suggest that without the moon, tides would be 1/3 of the size they are now. High tides would be much smaller than they are now, and low tides would be even lower.

What about Triton's orbit makes it unique among large moons in the outer solar system?

Triton is unique among all large moons in the Solar System for its retrograde orbit around its planet (i.e. it orbits in a direction opposite to the planet's rotation). ... Triton's rotation is tidally locked to be synchronous with its orbit around Neptune: it keeps one face oriented toward the planet at all times.

Why is Triton much less heavily cratered than the other moons of Uranus and Neptune?

Triton shows evidence of surface activity nitrogen geysers and water volcanoes that seem to have erased most of the impact craters.

What are some physical and psychological effects of challenges of long-term space exploration or habitation?

Unfiltered radiation, no re-supply, gravity fields, bone loss, muscle loss,

What may have caused Uranus' axial tilt?

Uranus is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees—possibly the result of a collision with an Earth-sized object long ago. This unique tilt causes the most extreme seasons in the solar system.

How do we know what the surface of Venus looks like?

We can't see the surface of Venus from Earth, because it is covered with thick clouds. However, space missions to Venus have shown us that its surface is covered with craters, volcanoes, mountains, and big lava plains.

What is the source of Io's volcanic activity?

tidal heating

How does triangulation allow one to find distance to objects without physically measuring these distances?

triangulation: If we measure the baseline and angles A and B, we can calculate distance .without direct measurement.