Earth Science Final Exam - Part 1

• Chondrites

1 of two types of stone meteorites. Cosmic sediment that have never been altered nor melted greatly since first compressed together.

• Achondrites

1 of two types of stone meteorites. Igneous rocks that have been at least partially melted and recrystallized.

Lincoln Near Earth Asteriod Research telescope

1998, a new asteroid detective hit the skies: the Lincoln Near Earth Asteroid Research (LINEAR) telescope, built in Socorro, New Mexico (Fig. 12.2). This is a very sophisticated and highly sensitive electro-optical detector with something called a CCD (a charge coupled device), which is an array of light-sensitive elements that can record very faint images. As of 2011, LINEAR has found over 231,000 new objects; 2,423 of these being near-Earth asteroids, and 279 comets.

• Galileo

After 14 years of flight time and 8 years collecting data around Jupiter, Galileo was deliberately destroyed by sending it crashing into Jupiter's crushing atmosphere. Galileo changed the way we think of the Solar System. First probe to fly past an asteroid: 951 Gaspra and 243 Ida.

• Fusion crust

Any melting at all will normally produce this. Which is on the object, a layer of glass.

Kirkwood gap

As Jupiter's gravity confined the asteroids into a more or less restricted area. it also dictated their locations within that belt. Plots of their mean distances from the sun revealed gaps in the belt where no asteroids existed. Daniel Kirkwood noticed that the distances between the gaps corresponded to simple factions of the orbital period of Jupiter, within these gaps, the gravitational perturbations are particularly strong.

Where are most asteroids found in the solar system?

Asteroid belt

Where in our solar systems do many asteroids reside?

Asteroid belt

Father of Meterotics

Chaldni

• Calilean satellites

Europe, Ganymede, Callisto, and Io

• Pioneer 11

First spacecraft to fly-by.

• Cassini-Huygens Mission

First spacecraft to orbit Saturn.

Betyls

Hebrew for home of God, meteorites.

Family

Hirayama surmised that the breakup of an asteroid into a collection of fragments, which would result in similar orbital characteristics for these bodies.

• Achondrite

If the fragment is the product of crystallization from a magma, we don't call it igneous rock it is a achondrites. Also subdivided into eucrites, basalt sherogttite, aubrites, and many more.

• Shepherd Satellite

Little satellites that occur here and there throughout the rings.

Why is there an asteroid belt? How did it form?

Lots of objects were being found in the space between Mars and Jupiter, and together they constituted the Asteroid Belt. Material represents stuff that never assembled into a planet at all - its primordial material left over from the early days of the solar system assembly. Computer modeling suggests that the enormous force of neighbouring Jupiter prevented it from becoming a planet.

• Igneous rock

Magma is formed by melting pre-existing rock at very high temperatures; when that molten rock crystalizes to a solid it becomes igneous rock.

• Regmaglypts

Meteoroid has no heat shield, the surfaces of some meteorites are marked with depressions resembling thumbprints that form by ablation.

Apollos

Most have an orbit that brings them through the orbit of Earth (i.e., they cross Earth's orbit), and these are particularly worth watching closely! Earth is hit by an Apollo object once every 250,000 years on average.

Kaaba Stone

Muslims pay homage in Mecca to a large meteorite.

21. Can comets carry viruses?

No!

Are all meteorites from the asteroid belt?

No. If an asteroids slams into Mars or the Moon with considerable force, chunks of the surface will fly off into space, and some gets trapped in Earth's gravitational field. So we have meteorites from both Mars and the Moon. Harder to get from Venus, it will go to the sun.

• Voyager 1 & Voyager 2

Provided data for the recent Cassini-Huygens mission.

• Mimas

Saturn's satellite.

23. Can you see comets with the naked eye?

Sometimes, when vert bright

• Star Trek V

The Final Frontier

• Momentum:

The force required to change its motion depends on this. It is the product of the body's mass, the amount of material it contains, and its speed or velocity.

• Cassini Division

The major division between A and D

Atens

These asteroids have orbits less than 1 AU - which means that most of the time they are within the orbit of Earth, though they may cross Earth's orbit when they're at their farthest from the Sun.

Amors

These commonly cross the orbit of Mars; they get teasingly close to the orbit of Earth, but don't cross.

• Prometheus and Pandora

These satellites act as "shepherds" to the F Ring

• Plutonium nuclear reactor fuel cell

Used to launch Cassini-Huygens mission

• Inertia

a body's resistance to a change in its motion, all bodies in motion posses this

Meteorite

a fragment (any size) of either a meteoroid or asteroid that lands on Earth`s surface. Please remember - it is not called a meteorite until it actually lands on surface.

• Find

a meteorite that is exactly what you'd expect, you more less stumble across it and you have no information of when it got there.

• Fall

a meteorite whose entry though the atmosphere has been witnessed, and someone has recovered a piece of the object.

Asteroid

a natural rocky object in space measuring 100 m to several hundred kilometres in diameter.

Meteoroid

a natural rocky object in space measuring from a few millimetres to 100 m in diameter.

2. What is the simplest life form we are aware of?

a. Bacteria. They reproduce and metabolize.

3. Is a virus a life form? Why or why not?

a. No virus can't life without host cells, they are considered fragments not cells.

5. What is the role of DNA? RNA?

a. One form of nucleic acid is known as DNA. Which carries the genetic information of all organisms. Primary role of DNA is to contribute the information required for production to regulate chemical reactions in cells. b. RNA carries out the coded instructions given by DNA.

It's important to learn whatever we can about asteroids because

a. They represent very primitive material left over from formation of the Solar System b. Much water and organic material came to Earth from them c. Sooner or later a large asteroid impact is likely to put an end to many terrestrial species (including humans)

• Cells

all organisms that have the essential characteristics of life are composed of discrete units known as cells.

Near Earth Asteroids

also known as Near Earth Objects, not all asteroids orbit within the main asteroid belt. Some follow orbits that bring them close to Earth.

Ceres

asteroid that has been classified as a dwarf planet.

• Trans-Neptunian Objects

beyond the orbit of Neptune lurk millions of icy bodies.

• Zones

clouds are organized in these. A result of the high rate of rotation of the planet. Are regions of rising gas. Tend to be white or yellow. Appear to be high-pressure regions of rising gas that cools as it rises and forms clouds higher in the atmosphere where they receive more sunlight and look brighter.

• Belts

clouds are organized in these. A result of the high rate of rotation of the planet. Some shade of reddish brown. Dark belts are higher than that of the light zones, implying that the former are lower in the atmosphere. Belts appear to be regions of descending gas.

Main asteroid belt

concentration of object, thousands of asteroids discovered in the gap between Mars and Jupiter. Appears to be mostly empty.

Carbonaceous asteroids

dark carbon rich minerals in the surface have very low albedos.

• Oblateness

doesn't have a hard surface, and rotates so fast, that it's oblateness is detectable.

• Iapetus

enormous impact crater, but it is clearly very old because many younger craters appear inside.

• Ablation

erosion process by removing small masses. The atmosphere reduces the meteoroid's momentum by creating a drag on it, thus slowing its velocity. It further reduces its momentum by heating the meteoroid until it begins to lose mass by the ablation process.

• DNA or RNA:

fragments.

C-type asteroids

high carbon content or 'carbonaceous', 75% of known asteroids; roughly similar composition to the Sun, minus the volatile elements.

S-type asteroids

high silicon or 'silicaceous', 17% of known asteroids.

E-type asteroids

highest albedo 40%. E for mineral enstatite.

c. Why does Triton have an atmosphere?

i. Density gives the satellites an escape velocity of 1.4 and with the intense cold (slow motion of atoms) to retain a very tenuous atmosphere.

What are comets made of?

i. Ice, frozen gases and miscellaneous rock dust/fragments travelling through the solar system.

25. Why is it unlikely to find planets with life orbiting: -Binary stars -Large stars -Small stars

i. Most planetary orbits are unstable and would not last long before they were swallowed up by one of the stars or ejected from the system. II. The size of the habitable zone depends on the temperature of the star. Hot stars have larger habitable zones - the planets must be more distant to remain cool, but those stars don't stay stable long enough. III. Small stars much smaller than the Sun won't work either because they are too cool. If those star systems included a planet in the right temperature range, it would likely be so close to the star it would be tidally coupled, and one side would always face the sun.

b. Triton is very cold - what element is liquid on the planet and how does this affect surface features?

i. Nitrogen "ground water".

d. What is a probable source of heat that drives activity on Triton?

i. The idea is that Triton was once an independent planet of ice and rock plying its own orbit about the Sun. The theory suggests that Triton strayed too close to Neptune and was captured by the gravity of the more massive planet about four billion years ago. For the next billion years, it swung in a highly elongated orbit, crashing into any satellites Neptune originally had beyond the ones known to be near the planet. Each time Triton passed close to Neptune, the tides caused by the big planet's gravity would be strongest. When Triton reached the elliptical orbit's far end, the tides would be much weaker. Astronomers calculate that the constant pulling and relaxation of Triton would have generated enough internal heat to turn the satellite molten. Two to three billion years ago, through natural orbital evolution, Triton's orbit became circular, the tides subsided and the surface froze. This scenario explains most of what we see, but some regions on Triton, such as the bizarre "cantaloupe terrain", remain puzzling.

a. Why might Triton crash into Neptune?

i. Triton is nearly circular, but travels backwards. Only large satellite in the solar system with a retrograde. ii. While it is completely stable right now, at some very distant future time, it will either break up or crash into Neptune.

Describe a comet's orbit

i. Usually elongated elliptical paths that are anchored.

What is a comets orbit anchored to?

i. Within either the Kulper belt or the Oort cloud.

• Tidal heating

important for Europa and apparently provides enough heat to keep the little satellite active.

• Orbital response

in the time is takes Ganymede to orbit once, Europa orbits twice and Io four times.

S-type

large numbers reaching Earth are apparently not indicative of large numbers of S type in space. 16% are chondritic compositions, rest are achondrites.

• Irons, stony irons, and stones

least sophisticated classification based on the very general mineral content.

• Residual rock

material left behind that didn't melt.

Titus-Bode Law

mathematical relationship of planet positions in the solar system.

• Mass spectrometer

measures the amounts of very selective radioactive isotopes in a sample to determine age of meteorite.

• Obliquity

mere 3 degrees.

M-type asteroids

metallic, most of the remaining asteroids.

• Petrographic microscope

meteorites are studied under this. Every mineral has diagnostic optical properties that allow us to know exactly what the mineral composition of the rock is.

4 Vesta

most thoroughly observed asteroid, one of the brightest in the sky and at times just visible to the unaided eye.

• Kinetic energy

moving mass also has energy associated within its motion. Also involves the body's mass and velocity, but kinetic energy increases exponentially with velocity. Falling meteorite's kinetic energy can convert to other forms of energy.

Trojan asteroids

named after the heroes of the Trojan. Like cosmic sink-holes, the Lagrangian points have trapped chunks of debris now known as Trojan asteroids.

• Life

needs energy.

1. Definition of a gas giant planet (a.k.a. Jovian planet or ice giants)

o A large, low-density planet composed primarily of hydrogen, helium, methane, and ammonia in either gaseous or liquid state.

16. What is the Oort cloud? How did it form?

o A spherical cloud of icy bodies believed to extend from 10,000 to 100,000 AU from the Sun. o Contains several trillion icy bodies. They are very cold and lack comas and talks, and are invisible. o They entered isotropically (i.e., they showed no preferred direction of entry); 50% of them had a retrograde orbit and 50% a direct or prograde orbit. They really had a truly random distribution.

10. Why are the lives of short-period (active) comets limited?

o According to Kepler's third law, the short-period comets do not venture far beyond the distance of Pluto at aphelion. o The nuclei are losing mass at rates that cannot be sustained for very long. o The active comets are under the gravitational control of the planets.

4. What do comets represent?

o Building blocks of life.

19. Have we ever collected material from a comet? What material did they find?

o Collected dust and ion matter and this found a new range of organic compounds and mineral structures they did not expect. o Comet Wild 2 (pronounced "Vilt 2") was visited by NASA's Stardust spacecraft in January, 2004. The Stardust mission was to collect material from the coma and tail and bring the sample back to Earth for detailed analysis o The roughly 5 kilometre wide nucleus of Comet Wild 2 probably formed in the Kuiper Belt about 4.5 billion years ago, just after the birth of the Sun. A close encounter with Jupiter in 1974 pushed it into a new orbit that brings it closer to the Sun. Since then, about a metre of material has been stripped away from the surface of the nucleus. o Because Wild 2 had been quietly resting in the freezing conditions of the outer Solar System for 4.5 billion years prior to 1974, the material from the nucleus captured by Stardust is considered to be pristine. Studying the samples in labs has provided a wealth of data. Scientists found a whole new range of organic compounds plus a variety of mineral structures they had not expected. o The comet has steep-walled craters and towering protrusions. Jets of material shoot out from its insides and dense clouds of dust swirl over the surface. Two of the depressions in the surface look like giant footprints.

1. What are comets?

o Comets are believed to be the oldest, most primitive bodies in the Solar System, possibly comprised of some of the basic building blocks of life. o Small, but over 100m. Mainly icy objects that streak through the solar system along long sun-orbiting elliptical tracks.

18. What is Comet Halley coated with? What is at the surface of Comet Borrelly?

o Halley is covered in a layer of organic material. o Surface of Borrelley is dark charcoal, smooth, rolling plains containing brighter regions that are present in the middle of the nucleus, and these seem to be the course of dust jets seen in the coma.

22. Why has Halley's comet one of the most well known comets by humans?

o Halley's Comet has a very elliptical orbit. At its closest it is about 88 million kilometres from the Sun, within the orbit of Venus, and at aphelion it recedes to 5,250 million kilometres, beyond the orbit of Neptune and the Kuiper Belt. At its brightest recorded return (AD 837), it passed by Earth at only 6 million kilometres, and contemporary reports tell us that its head was as brilliant as Venus, with a tail stretching 90 degrees across the sky. o Another bright return was that of 1066, before the Battle of Hastings; the comet caused great alarm among the Saxons, and it is shown on the Bayeux Tapestry with King Harold toppling on his throne and the courtiers looking on aghast. o In 1301, it was seen by the Florentine artist Giotto di Bondone, who used it as a model for the Star of Bethlehem in his picture The Adoration of the Magi - even though Halley's Comet was certainly not the Star of Bethlehem, since it returned in 12 BC. o At the return of 1456, the comet was condemned by Pope Calixtus III as an agent of the Devil. o It was prominent in 1835 and in 1910, but unfortunately not in 1986, when it was badly placed and never came within 39 million kilometres of Earth, and though it became an easy naked-eye object it was by no means spectacular. o The next return (2061) will be no better. We must wait until 2137, when it will again be a magnificent sight. o The fact that Halley's Comet can still become brilliant shows that it came in fairly recently from the Oort Cloud. It loses about 250 million tons of material at each perihelion passage, but it should survive in more or less its present form many years to come.

15. How do icy Trans-Neptunian Objects become comets? (2 ways) - How do we tell which process created individual comets?

o If there is a bunch of icy bodies out past Neptune called Trans-Neptunian Objects (several of which appear to be at least as large as Charon, and now we know there's at least one larger than Pluto), how do some get to be comets that we see? That is, what actions account for knocking them out of their orbits and sending them sailing into the inner Solar System? o The first theory is that every once in a while the planets are arranged such that their cumulative gravitational effect 'kicks' a scattered disc icy body (or a TNO) out of its stable orbit and into an eccentric elliptical path that brings it into the inner Solar System. Here, the planet with the greatest influence is Neptune - just as Jupiter was responsible for booting asteroids out of unstable positions in the asteroid belt. o The second theory is that, perhaps due to the same gravitational stress, two or more icy bodies collide, and fragments of the parent(s) come sailing through the inner Solar System as comets.

14. For what two reasons is the Kuiper belt significant for the study of the solar system?

o Kuiper Belt objects are extremely primitive remnants from the early accretional phases of the Solar System. i. The inner, dense parts of the pre-planetary disk condensed into the major planets, probably within a few millions to tens of millions of years. ii. The outer parts were less dense, and accretion progressed slowly. Evidently, a great many small objects were formed. o The outer edge of the Kuiper Belt that overlaps with the scattered disc is the source of at least some of the short-period comets.

5. As well as possibly being the main source of water to the inner planets, they may also have been the source of many of life's basic building blocks (amino acids particularly). I. Why would life not be able to survive on a comet?

o Life requires temperatures where water can exist in its liquid form. Some rare, single celled organisms on Earth are know to survive at temperatures as low as -30 °C, but that's much warmer than the temperature of a comet nucleus (-50 to -250 °C). The low temperatures, together with high vacuum, radiation from cosmic rays, exposure to ultra-violet light and solar wind particles, would prevent life from surviving on a comet.

2. What do we think life requires to develop?

o Liquid water, roughly similar to Sun (not too hot not too cold).

9. What is the difference between long-period and short-period comets?

o Long period comets: majority of comets take hundreds of thousands, some even millions, of years to complete a single orbit around the Sun. o Short-period comets: conventionally defined as those having orbital periods of 200 years or less. Return for another encounter within a relatively short time. (Do not travel farther than the distance of Pluto).

1. What are the 6 possible places we hope to find evidence of life in our solar system (other than Earth?

o Mars, two satellites of Jupiter (Europa and Ganymede) and two of Saturn (Encedadus and Titan). o Potentially Venus as well.

12. Where in our solar system are comets formed? Are they old or young?

o Most say it comes from the Kulper belt, which is wrong. o Most originate from a wide and diffuse region called the scattered disc just past the Kulper belt. o They were formed at the beginning of the solar system but then stored in a cold place, these places are the Oort cloud and Kuiper Belt, they are hella old o One of several things may then happen. The comet may simply swing round the Sun and return to the Oort Cloud, not to be back for many centuries - or even thousands or millions of years. It may fall into the Sun, and be destroyed. It may be perturbed by a planet (usually Jupiter) and either thrown out of the Solar System altogether, or else forced into a short-period orbit which brings it back to perihelion after a few years. Or it may collide with a planet, as Comet Shoemaker-Levy 9 did in July 1994, when it impacted Jupiter. But really brilliant comets have periods so long that we cannot predict the date of their appearance, and they are always apt to arrive without warning and take us by surprise.

6. What are the 4 parts of a comet, what are they composed of, and how do they form?

o Nucleus: The nucleus is a repository of dust and frozen gases. The low density suggests that comet nuclei are not solid objects o Coma: Nucleus approaches the Sun and that warms the surface and the solid ice turns to vapour which produces an atmosphere surrounding it known as the coma. Coma becomes larger and brighter as the comet nears the Sun, part of the coma is swept into an elongated tail. Water vapour, carbon monoxide, carbon dioxide, and other minor components. This refractory (non-volatile) dust that together with gases forms first the coma and then the tail, consists of some silicate minerals and carbon rich CHON (Carbon-Hydrogen-Oxygen-Nitrogen) grains. There is probably about as much mass of dust as there is of gas. Together, the coma and the nucleus form the head of the comet. o Tail (2 parts): When comets come close to the sun, they sprout two tails. One of them is called the dust tail (made of small dust particles that sputter off the nucleus. A longer blue-coloured ion tail is made of glowing gas (due to electrons and ions getting together to form uncharged molecules). Push straight away from the sun by the solar wind. The brighter dust tail traces the comet's curve orbit.

13. What is the Kuiper belt? How did it form?

o Observations show that most are confined within a thick band around the ecliptic, leading to the realization that they occupy a ring or belt surrounding the Sun. This ring is generally referred to as the Kuiper Belt o Kuiper belt is from the orbit of Neptune to 50 AU, this makes a belt that orbits the sun o Formed from remnants of proto-planetary disk

2. Where do they come from?

o Outer solar system. o Leftover from the formation of stars and planets. o As they warm within the inner Solar System from the (even slight) heat of the Sun, the frozen gases (water, ammonia, methane, and a few others) begin to vaporise, leaving visible tracks across space.

11. What is the typical life span of a short-period comet?

o The "dynamical" lifetime of a typical short period comet is about 1/2 million years.

3. What are they made of?

o They contain the remains of materials used in the formation of stars and planets, holding volatile, carbon-based rich elements that are likely to provide clues about the nature of our Solar System. Importantly, they may provide evidence that comets brought water to Earth, making life possible.

17. Based on their orbits, how do we know that long-period comets come from the Oort cloud?

o They must come from the Oort cloud because if they came from anywhere closer their orbits would be altered by the planets in the solar system o But the Oort Cloud surrounds the Sun in all directions, instead of being confined near the ecliptic plane like the Kuiper belt. In fact, the geometry tells us the bodies in the Oort Cloud could never have formed at their present location; had they formed from the solar nebula, we would expect them to be distributed in a disk and not in a sphere. Also, their density is too great; the solar nebula would not have been dense enough so far from the Sun. Astronomers think the objects now in the Oort Cloud formed as icy planetesimals in the outer Solar System, near the present orbits of the Jovian planets. As those planets grew more massive, they swept up many of these planetesimals, but they would have ejected many trillions into long orbits leading far out of the Solar System. These are the objects that became the Oort Cloud.

1. Why does living matter need energy?

o To survive and create offspring o Reproduce and carry out processes by which they can grow and live.

7. How are comets related to meteor showers?

o When Earth passes through the stream of dust of a comet, we see a meteor shower.

• New Horizons space probe

proceeded through the Jupiter system and has cut through the orbit of Saturn system as it sped on toward Pluto.

• Fireball

produced by large chunks of rock and iron that were knocked off asteroid parent bodies by collisions.

Albedo

proportion of light reflected from an object, the range is 0 to 1.

Differentiated

really large asteroids can become differentiated, just as planets do. This means that they have been heated by radioactive decay and released during accretion, enough that their interior starts to melt.

• Chrondrules

refers to the small rounded inclusions in chrondrites. Formed from a hot cloud of gas and dust condensing in the early solar system

• Satellite Io

satellite orbiting Jupiter.

• Callisto

satellite with a body that apparently never chemically differentiated.

• Europa

satellite with significant liquid water ocean beneath its ice surface.

• Ganymede

satellite with water "slush" ocean beneath a solid ice cover.

Dawn

spacecraft launched by Nasa to learn about Vesta powered by ionized Xenon atoms.

• Nucleic acids:

sugar, phosphate group, and a nitrogen compound.

• Great Red Spot

swirling vortex of clouds.

• Troposhore

temperature rises rapidly from top to bottom of layer.

• Primitive achondrite

the fragment is a chunk of residual product.

Fireball

the light associated with a large meteoroid or asteroid as it interacts with the atmosphere.

Meteor

the visual streak of light associated with passage of a small meteoroid through Earth's atmosphere; the heat energy producing the light is a result of friction between the object and molecules of gas in the atmosphere. Remember - a meteor is not the object, only the light phenomenon.

• Electron microprobe

uses a tiny beam of electrons to impact micron-size volumes of the sample and tell us what elements are present in that volume and in what portions.

17. Does Pluto have satellites?

• 4: Nix, Hydra, Kerberos and Styx.

12. What are the rings composed of? Do other gas giants have rings? Compare differences in formation of rings among the gas planets.

• 95% water ice. • The ring systems of the other giant planets - Jupiter, Uranus and Neptune - are drab appendages compared with the sparkling beauty of Saturn's adornment. If any of these other ring systems surrounded Saturn, the ornament would be either barely visible or totally invisible to a visual telescopic observer on Earth. The rings of Jupiter are dull and diffuse; those of Uranus and Neptune are downright dark - among the least reflective objects known in the Solar System.

17. What is the Cambrian explosion and when did it happen?

• A little over a half-billion years ago something happened, perhaps a change in Earth's climate, and life exploded into a wide diversity of complex forms. • This marks the beginning of the Cambrian period, and is sometimes called the Cambrian explosion. There are no fossils of land plants or animals from this time however.

10. What evidence of life has been found (or claimed to have been found) in meteorites?

• A meteorite found to contain a wide variety of organic compounds, including many amino acids. Very similar to Miller experiments. Including, many amino acids unknown from terrestrial biological sources.

24. When looking for planets outside of our solar system that might have life, what characteristics scientists look for? What is the goldilocks zone?

• A trove of extra-solar planets has been discovered as the Kepler mission produces ever more data. One of the most exciting finds so far is the discovery of a red dwarf star called Kepler-186, which is 491 light years from Earth. Up to 6 planets are thought to be orbiting Kepler-186, each one being given a simple letter designation. For comparison to our Solar System, see Figure 19.12. The extent of the habitable zone (sometimes called the goldilocks zone), where water can exist as a liquid, is indicated for both systems. Planet Kepler-186f, discovered in 2014, has a radius similar to Earth, and sits within the habitable zone! • Another exciting find was the 2015 discovery of Kepler-452b, a potentially Earth-like planet (it's about 1.6 times the size of Earth) in the habitable zone of a Sun-like star. Its host star is six billion years old, which means it's likely to be a bit brighter than the Sun, so it's possible that Kepler-452b is more like Venus than Earth. Even though Kepler-452 is 1400 light years from Earth, this is one of the most important exoplanet discoveries. • An as-yet unconfirmed exoplanet, Tau Ceti e, could turn out to be an Earth-like exoplanet orbiting a G-class (i.e., Sun-like) star. What makes this particularly interesting is that Tau Ceti is just 11.9 light years from the Sun. Tau Ceti e is thought to be less than twice the size of Earth, and to sit within the habitable zone. If it has an Earth-like atmosphere, Tau Ceti e could have a surface temperature of 68 C. • It is going to take some time to gather evidence to support any climatic model for the planets that we're finding. But one thing is very, very obvious - and is making astronomers optimistic: there can be little doubt that such star systems are common throughout the Universe.

28. What are the 3 common characteristics of a mass extinction on Earth?

• A very short period of catastrophism, global extent, and turmoil in both marine and terrestrial environments.

7. What is the difference between an achondrite and a primitive achondrite?

• Achondrite is a fragment of crystallization from magma, whereas primitive achondrite is a chunk of residual product.

12. How does the atmosphere slow a meteoroid's momentum?

• Acts as a brake using friction.

3. What are the common features shared by the gas giants?

• All have atmospheres of hydrogen and helium, with more hydrogen than helium. • On Jupiter and Saturn, the boundary between atmosphere and body of the planet (what we'd call 'surface') is gradual: from gas to liquid. On Uranus and Neptune there may actually be a sharp bounding surface between gas and liquid. • All have very hot cores: perhaps 20,000 K for Jupiter and Saturn and 7,000 K for Uranus and Neptune. • All have cores that are sometimes called 'rocky' but are a mix of heavy elements in a solid state (somewhat similar to Earth's inner core) (Fig. 2). • All are surrounded by systems of rings and natural satellites. • All rotate rapidly, resulting in strong atmospheric winds that produce cloud bands that parallel their equators. Jupiter rotates fastest, thus has the most prominent bands.

13. How old are Earth's oldest fossils?

• All of knowledge of bacteria and the formation of Earth is guess-work because our oldest fossils are 3.5 billion years old and the best preserved specimens come from Western Australia.

3. What is a Trans-Neptunian Object?

• Any sized objects in the Solar System that orbit the Sun at a greater distance - on average - than Neptune (we say 'on average' to accommodate those objects with highly elliptical orbits). So TNOs include everything in the Kuiper Belt and the Oort Cloud, which is out even further than the Kuiper Belt.

17. What size of an impactor could cause global effects on Earth?

• Apollo objects will not hit Earth in the immediate future, but the bad news is that there are about 1000 of these near Earth asteroids larger than 1 lm in diameter. The minimum size of an impactor that could cause global effects on Earth.

19. What is the definition of a PHA?

• Asteroid minimum of 150 m diameter and comes closer than 0.05 AU to Earth. As of 2012, there were 1325 mapped.

20. You do not need to memorize the Torino Scale, but you should have an idea of what it means as you move to higher and higher numbers.

• At a 8, 9, 10 level collision is certain. • 10 suggests future life is at stake. Most life would cease. • Apophis was a 4. Now reduced to 0. Aimed to impact on Friday April 13 2029. • Ratings change as we get better views.

9. What in the atmosphere makes the planets appear blue-green?

• Atmospheric methane. • When sunlight strikes the upper atmospheres, the red wavelengths are absorbed by methane, resulting in reflected light that has a high proportion in the green to blue spectrum.

6. Why are scientists so excited about studying carbonaceous chondrites?

• Because they appear to participate in accretion. • These carbonaceous Chondrites specifically contain carbon that may be tiny diamonds, graphite or even hydrocarbon organic molecules. Contain many hydrous clay sillicates as well as salts. Closely matches the sun more than any other material we have observed.

6. What is the difference between C, S, and M type asteroids?

• C type has high carbon, S type has high silicon, and M type is high in metallic.

11. Name the 4 Galilean satellites orbiting Jupiter:

• Callisto - ice and rock, undifferentiated interior, little radioactive heat may melt some ice, only weak magnetic field • Ganymede - silicate rock and ice, completely differentiated with molten iron core, surface of ice covers a salty liquid water ocean, generates its own and magnetic field. Has an oxygen-rich atmosphere. • Europa - rock and metal, metallic core, no magnetic field, temporary atmosphere formed as ice is abraded by Jupiter's radiation. • Io - iron rich core and silicate mantle, partially molten, temporary atmosphere from volcanic gases

18. What is a possible source of the water/ice in the rings?

• Cassini has detected a massive eruption of atomic oxygen spewed into a huge cloud on the dark side of Saturn's rings just as the craft was preparing to enter orbit. While such a concentration was a big surprise, the detection of oxygen atoms was not (see previous point). Hydroxyl ions had already been detected earlier (actually all the way from the Hubble Telescope).

8. What is our definition for "Life"?

• Cellular organisms: o Carbon and water based o Contain genetic information sufficient to reproduce o Possess the abilities to undergo metabolism o Respond to stimuli o Adapt to their environment in successive generations

4. Within the Stones category, what is the difference between chondrites and achondrites

• Chondrites have never been altered or melted, whereas achondrites have.

2. Do these planets have rings? What might be the source of material for the rings?

• Circled by thin dark rings.

• Is the surface of Titan hot or cold?

• Cold at -179 Celsius.

10. Uranus has a belt-zone cloud pattern (as also seen on Jupiter and Saturn) - we keep seeing this theme - it would be prudent to understand how/why these form.

• Combination of the temperature gradient plus rotation of the planet gives rise to a belt-zone cloud pattern.

5. What did we learn by watching the Shoemaker-Levy 9 comet impacting Jupiter?

• Comets are very common and Jupiter has a strong gravity, so it gets hit by comets more often than most planets. • It passed very close to the planet and was pulled into at least 21 pieces that looped away from Jupiter in long elliptical orbits. • Impact site just out of sight as seen from Earth. Impacts were visible form the Galileo spacecraft. Rising fireball was visible above the horizon. Impact sites remained bright in the infrared as the rotation of Jupiter carried them into sight from Earth. At visual wavelengths, impact sites were dark smudges that lasted for many days. • Fragments were no bigger than a km or so in diameter and contained a fluffy mixture of rocks and ices. Hit Jupiter at 60 km. Produced fireballs almost 3000 km high. Some of the dark smudges were larger than Earth. • Astronomers were able to fine-tune the models to better represent Jupiter's atmosphere. • Reminds us that planets are hit by large objects.

12. What is the difference between conduction, convection and radiation?

• Conduction: Heat is transmitted through collisions between neighbouring molecules. • Convection: Heat transfer caused by mass motion of a fluid, such as water when the heated fluid is caused to move away from the source of heat, carrying energy with it. • Radiation: Emission or transmission of energy in the form of waves or particles through space or through a material medium.

• What is special about the volcanic activity on Titan

• Cryovolcanoes to signify that their product is not hot lava but cool to cold water and ices. Speculation that there are plate tectonics.

14. Do we know what causes the appearance of "spokes" on the B ring?

• Dark radial features that move in curious patterns on the B ring. • Named spokes due to their likeness of spokes on a wheel. • No consensus view for origin, but they seem to be seasonal phenomena.

9. What was the miller-Urey experiment? What did they create (and how)? What was the significance?

• Demonstrates the mechanisms by which inorganic elements could combine to form the precursors of organic chemicals • Discharged electric sparks into a mixture that they thought resembled the primordial composition of the atmosphere • In the experiment amino acids appeared • Amino acids are the building blocks of every cell.

3. What is the difference between irons, stony-irons and stones? Which is the most commonly found on Earth?

• Describes what you see when you look at a meteorite. The iron consists almost entirely of iron and metal alloys. Stony-irons are a 50/50 mix. Stone are almost all non-metallic silicate/oxide material. • Stones make up 93% of all meteorites.

10. Why are the most plentiful asteroid types (carbonaceous chondrites) the least common meteorites found on Earth?

• Difficulty of removing them from the outer fringes of the belt, where they normally reside.

11. Why are there "gaps" in the rings of Saturn?

• Division between and A and B is known as Cassini Division. Planet has rings = D, C, B, A, F, G. • Division is caused by gravitational perturbations by Saturn's satellite Mimas. • The other smaller gaps are generated through much more complex interactions with other satellites and with large particles within the rings.

6. Saturn and Jupiter are similar in that there is no clear division between the atmosphere and the surface of the planet. Be sure you are aware of why this is happening.

• Due to slow gradual change from gaseous atmosphere to liquid planet.

2. What is the name of the plutoid that is bigger than Pluto?

• Eris

20. What are the arguments for/against life on the satellites Europa, Ganymede and Titan?

• Europa has the best chance, seems to have a liquid-water ocean below its icy crust, and minerals dissolved in that water would provide a rich broth of chemical evolution. Conditions have not remained stable for freezing by tidal heating. It may have been frozen in the past. • Ganymede, if it has a liquid ocean then it has some possibility of supporting life as well. But not concrete conclusions on its geology. • Titan has an atmosphere of nitrogen, argon, and methane and may have oceans of liquid methane and ethane on its surface. Titan therefore bears some resemblance to Earth 4.6 billion years ago. These chemicals are vital for amino acids.

10. What are the 3 principles in comparative planetology?

• First, a body's composition depends on the temperature of the material from which it formed. This is illustrated by the prevalence of ice as a building material in the outer Solar System where sunlight is weak. • The second principle is that cratering can tell us the age of a hard surface. • Finally, we will see that internal heat has a powerful influence over the geology of these larger satellites.

10. How is the light of a fireball formed? Why do the colours change?

• Formed by massive meteorites. • Colours change from two sources: o Composition of the vaporizing material and the composition of the luminous air surrounding the hot meteoroid. Many elements give off diagnostic colours when vaporized. o Progresses along its path will often change its colour. A fireball will turn from white to red immediately before it is extinguished. Usually because of atmospheric gases flowing, the fireball appears much larger and closer than it is.

4. How/when do the gas giants form

• Formed within the first 10 million years of development of a star-planet system or they didn't ever develop. • All volatile and liquid elements that would be given off by an early star would gather quickly into frozen blobs in the cold outer reaches of the system. They would grow and their gravitational attraction would increase rapidly. • They'd start pulling greater and greater quantities of volatiles and liquids into themselves. Inevitably, the larger masses would start interfering with the orbits of the slightly smaller masses, and the combined gravitational/rotational interactions would have the effect of flinging the smaller ones either out to the margins of the planetary system or in toward the central star. • Neptune would pass a protoplanet to Uranus, which would pass it to Saturn, which would pass it to Jupiter. Jupiter may just assimilate it, or it may toss it toward the Sun. Some of these protoplanets may have ended up as asteroids, some may have headed straight into the Sun (perhaps bashing one of the terrestrial planets on the way), and some may have been flung straight past the Sun and out of the Solar System completely. It is during this period that the planets 'adjusted' their orbits to the relatively stable sequence we see now. • Most were gobbled up, but a few - their number being determined by the ratio of total mass of all satellites to the mass of the 'parent' planet - survived in fairly stable orbits.

12. What is the structure of Pluto's interior (as far as we can tell right now)?

• Frozen nitrogen o Water ice • Mix of silicate rock and water ice. • 2/3 the size of the Moon and has a density twice that of water.

14. Which of these satellites might have some possibility of supporting life? Why?

• Galilean satellites has some possibility of bacteria-like life living in the liquid waters of Europa. • Some researchers suggest that enough oxygen could build up in Europa's oceans to support microbes, or even larger life forms. They postulate that such life forms could live without sunlight if they rely on chemical sources of energy in the oceans, rather than sunlight and photosynthesis. Recall that hydrogen and oxygen are formed at the surface of Europa where the ice is bombarded by high energy particles. If that oxygen, or oxygen from some other source, makes its way into the ocean it could provide an energy source for life. • Next best bet would be Ganymede - salt-water oceans.

2. How did the Cassini Huygens spacecraft get enough energy to reach Saturn's orbit?

• Gravity assists received from other Solar System bodies plus a small plutonium nuclear reactor fuel cell.

15. Do near Earth objects have circular or elliptical orbits?

• Highly elliptical orbits and are subdivided into categories according to the dimensions of their orbits.

10. Why is Pluto's surface not heavily cratered?

• Ices are very young or are geologically active.

12. Compare the structure of these 4 main satellites to each other with particular attention to how the size of the satellite and its proximity to Jupiter determine:

• If the body is differentiated (related to heat source, which varies among satellites) • If there is a liquid core (and consequently a magnetic field) • If there is an atmosphere • The density/composition of the satellite

5. What is causing Saturn to generate heat?

• Infrared observations show that Saturn is radiating 1.8 times as much energy as it receives from the Sun, telling us that heat is flowing out of its interior. So, it must be hot inside. In fact, it is hotter than we would expect. It should have lost more heat since it formed. Astronomers suspect that helium in the liquid hydrogen interior is condensing into droplets and falling inward. The friction of the falling droplets and the compaction of them in the core heat the planet. This heating is similar to the heating produced when a star contracts.

13. Why do Europa and Io have few craters (two different reasons)?

• Io is the most volcanically active body in the solar system. • Europa must resurface periodically. Liquid water from an underlying sub-ocean rises through cracks in the ice to flood over the surface.

8. Which direction does each of the tails point?

• Ion tails are pushed straight away from the sun • Dust tail traces the comet's curved orbit

3. Why is Saturn less dense than Jupiter?

• It is compacted.

1. How do we know that Jupiter is big?

• It looks big, satellite Io and its shadow against Jupiter. • Jupiter is normally the 4th brightest object in the sky. • 11 times Earth's diameter. • Satellites race around at high speed and don't fly off into space.

6. Does Jupiter have a magnetic field? How might it be formed?

• Jupiter has a magnetic field; we're not sure how it's generated but it likely is to do with differential motion by the different physical states of hydrogen (particularly the metallic state surrounded by the liquid state). In any case, the field is the strongest of any body within the Solar System except for spots on the surface of the Sun; it's 14 times stronger than Earth's. The strong magnetic field efficiently traps electrically charged particles (from the solar wind) and shapes them into a teardrop form of magnetosphere of radiation around the planet (Fig. 14.7). The trapped charged particles are so abundant, that they would do damage to instruments of any spacecraft flown through the magnetosphere.

2. What are the 4 gas giants in our solar system?

• Jupiter, Saturn, Uranus, and Neptune.

17. What the argument that suggests the rings might be old?

• Kerr realized that the Voyager had been wrong on at least one point: the rings are not uniform all the way around the planet. • Sometimes the satellites disintegrate, replenishing the ring material, and sometimes the ring material accretes into small satellites. If that's the case (and be aware that there are many more scientists opposed to that hypothesis than supporting it), then the rings would always look bright and fresh, and there's just no way that sort of property can be used to tell how old they are.

4. Where are the Kuiper Belt and the Oort cloud?

• Kulper Belt is outside the solar system. • The Oort cloud is even further out.

5. Jupiter is primarily composed of hydrogen in various states (e.g. gas, liquid etc.) Describe the structure of the planet (e.g. Fig 14.6). Does the liquid hydrogen ocean have a surface?

• Largest ocean in the solar system. • Gaseous hydrogen->Liquid hydrogen->Metallic hydrogen->Core of rock, metals and hydrogen compounds • There is no liquid hydrogen surface, the pressure and temperature is so great that liquid and gaseous are indistinguishable from one another

14. Stromatolites, some of the earliest complex organisms, produced oxygen, which was toxic to them - how did they survive? Is this process still happening today?

• Layered structures built by the secretions of prokaryotes form this. • In anaerobic environments (i.e., in environments lacking free oxygen), blue-green bacteria (prokaryotes) exist today, and they are virtually unchanged from their ancestors of 3.5 billion years ago. Because we can study them in labs, we know they produce oxygen as a by-product, yet it's quite obvious this by-product is a 'poison' to them - when exposed to free oxygen, they die. • Our oceans today don't have to same amount of enriched dissolved iron. As oxygen molecules built up and iron was used up, the environment began to change and prokaryotes weren't the only cells.

12. How/where might have amino acids linked together to form larger molecules?

• Link up to form proteins. • Young Earth was subject to extensive volcanism and large asteroid impacts that periodically modified the climate enough to destroy such delicate molecules exposed on or very near the surface. So complex molecules probably took advantage of the energy of hot springs well away from surface conditions.

22. What is a shepherd satellite and how do they stabilize rings?

• Little tightly associated with the rings. • Shepherd satellites will orbit Saturn just barely outside the ring with which its associate and the gravitational force of the satellite will drag the particles back toward it, thus controlling the energy of the particles and at least temporarily, stabilizing their obit. • New hypothesis - at some stage they disaggregate to provide material for the rings, at others they grow by accretion of that same ring material.

7. Why do Uranus and Neptune have less hydrogen and helium than Saturn and Jupiter?

• Lower escape velocity: the planets are just a bit too small to retain great quantities of the two lightest gases.

23. Under what conditions is it possible that life on Mars and Earth would be similar?

• Mars could have been the first planet to host life, but were carried to Earth via meteorites. Where Earth had a much more sustainable environment to host life. • Suppose, secondly, that we were instead to find life forms on Mars that have absolutely no common properties with those on Earth. It would certainly be our moral obligation to send (robotic?) cleaning crews up to sterilize all the terrestrial objects now sitting on the Mars surface, don't you think? Without that, there could be contamination of the Mars life, and whatever terrestrial life made it through the space voyages would likely be virile enough to completely wipe out Martian life.

9. How can asteroids be classified using albedo and spectral analyses? There is no need to memorize the names of specific types of asteroids.

• Matching children with parents. Astronomers recorded reflection spectra from dozens of asteroids.

9. How does a meteor shower occur? What is the difference between a meteor shower and a fireball?

• Meteor shower occurs because they strike Earth's atmosphere at nearly the same position along Earth's orbit and consequently we see their meteor trails each year against the same background of stars. • A fireball is produced from a single meteorite that is so massive it can survive atmospheric passage.

16. Where are meteorites on Earth often found and why?

• Meteorites fall over all regions of Earth with equal probability. • Deserts of Morocco, Oman, Antarctica, or in other places where it is easy to spot the ground. • Antarctica is great because its cold environment they remain pristine.

21. Why were scientists excited to see methane on Mars?

• Methane could be produced by some kind of volcanic activity such as occasional hot springs. But it can also be the product of currently active biological activity - just like Earth.

• What is the source of methane in the atmosphere on Titan vs. Earth?

• Methane is produced by biological activity, not possible on Titan. The source is mysterious it should have been broken down into more basic components long ago.

13. Explain how a meteoroid's mass and velocity affects its momentum and kinetic energy

• Momentum is the product of the body's mass, the amount of material it contains, and its speed or velocity. The more mass it has the faster it will travel. The greater the force needed to change its motion. • The greater a mass and velocity, the greater its kinetic energy. Unless a meteoroid possesses an enormous mass velocity is more important factor.

27. What are the drawbacks of communication with other planetary systems by radio waves?

• Nature places two restrictions on our ability to communicate with distant societies by radio. One has to do with simple physics, is well understood, and merely makes the communication difficult. The second has to do with the fate of technological civilizations, which is still unresolved, and may severely limit the number of societies we can detect by radio. • Radio signals are electromagnetic waves that travel at the speed of light. Because the nearest civilizations must be a few light years away, this limits our ability to carry on a conversation with distant beings. We would have to wait 20 years for a reply if people were 10 light-years away. • Astonishing amounts of computer power are needed to sort through weak signals looking for unusual patterns.

15. Why is there almost no methane on Charon, while Pluto has lots?

• Nearby Pluto has stronger gravity, and so it not only retains its own methane but captures some of that leaking off Charon. As a result, Charon's surface is nearly denuded of methane, leaving "rock-solid" H2O ice, which is not volatile at those temperatures.

17. What techniques do we use to analyse a meteorite? What can we learn from these tests?

• Need a mount of a very thin slice using a diamond saw and diamond powder. Studied using a petrographic microscope. • Identifying the minerals inside we commonly used the electron microprobe to chemically analyze them. • When we want to know old a sample is we use a mass spectrometer.

3. Contrast the internal heat of these two planets. Why might Uranus be cold? Where does Neptune's heat originate?

• Neptune has a core of 7000K. Uranus is 2000K colder. • Not 100% sure but think it has something to do with the huge impact even that flipped the planet over.

4. Neither Uranus nor Neptune can be seen from Earth with the naked eye - Explain (in general) what theories were used to predict their locations.

• Neptune moved slightly with respect to a star, but on subsequent night it was out of his field of view. • Adams determined the position of Uranus calculating what the exact deviation from Newton's laws was.

5. What is the name of the spacecraft that recently passed Pluto?

• New Horizons.

• What is the composition of Titan's atmosphere?

• Nitrogen 98% and 1.6% methane.

13. Is Charon a satellite of Pluto? Explain your answer

• No it is a binary planet system because the gravitational balance point is between the two planets. In order for it to be a satellite the balance point needs to be within Pluto. • That means Charon is not a satellite of Pluto (the combined gravitational point must be inside the parent planet for that). Binary stars are very common in the Universe - and maybe binary planets are too. But no Earth-bound craft or telescope has ever defined one before.

4. What is the interior structure of Saturn (e.g. core and various layers)

• No sharp distinction between atmosphere and the planet's body. Saturn does not have a "surface" in the same sense Earth does. Impossible to land on it.

18. What do we know about the composition of Eris?

• Objects like Eris that have wild and random orbits out at the edge of the Solar System are said to make up a Scattered Disc. Since their orbits bring them within the Kuiper Belt, the Scattered Disc can be said to start within the Kuiper Belt, but the Scattered Disc extends far beyond). When it was determined that Eris was spherical and larger than Pluto, it was called initially the 10th planet by NASA. • Unlike Pluto, however, the surface is grey and possibly coated with the same sort of polymer organic matter found in other outer system bodies. • One satellite, Dysnomia, orbits Eris. • Made from methane ice and is probably much like ice.

22. Was/is there liquid water on Mars?

• One hosted large bodies of liquid water, and that liquid water could have existed on Mars for a longer period of time than it took for life to evolve on Earth. • Given that, it really would not be at all unexpected that below the "ice table" of Mars, pockets of liquid water remain. If so, it's possible that those pockets contain active microorganisms.

9. What 4 kinds of ice on found on Pluto's surface?

• One side facing the moon, Charon has more methane ice, and the other more nitrogen and carbon dioxide ices. • Within the bright, heart-shaped region called Tombaugh Regio, is a smooth plain called Sputnik Planum that seems to be made out of nitrogen, carbon monoxide and methane. The smooth, uncratered surface of Sputnik Planum suggest that the ices are very young, or at least are geologically active. • To the south and southwest, Sputnik Planum is bordered by 3,400 m mountains of water ice - at 50 K water ice acts like rock compared with the nitrogen glaciers covering the plain

1. Definition of a plutoid

• Orbits the Sun at an average distance greater than that of Neptune. • It is massive enough that its own gravity brings it to hydrostatic equilibrium, making it near spherical. • Not cleared the neighbourhood around its path from other orbiting debris.

10. Does Saturn have a magnetic field? If so, what causes it?

• Perfectly symmetrical magnetic field. • Probably the interaction between the core and the metallic hydrogen inner mantle. • Much weaker than Jupiter.

1. What are the names of the 4 dwarf planets classified as plutoids?

• Pluto, Eris, Makemake, and Haumea.

11. What is a differentiated body?

• Process of separating out different constituents of a planetary body as a consequence of their physical chemical behaviour, where the body develops into distinct layers. Occurred on planets, dwarf planets, and the asteroid 4 vesta.

15. How does atmospheric friction affect the surface of the meteorite?

• Produces regmaglypts.

5. What is a chondrule? How might they have formed?

• Referred to bolded terms. • Not sure how they are formed, many ideas. • Popular one is that they condensed from a hot cloud of gas and dust, very early in the solar system history, by a 'flash-melting' of dust aggregates in the solar nebula.

9. What are the 3 classification of satellites (for Jupiter's satellites and elsewhere)? Compare the characteristics/formation/orbits of each kind.

• Regular: define the outer orbital reaches of a planet's domain in space. Io, Europa, Ganymede and Callisto. Are large, round, tend toward stable simple circular orbits, move through a plane in space that is roughly equal to the planet's equatorial plane. Hypothesis of how the formed - some nebula of gas and dust built the planet, and likely at the same time (this is what everyone now believes). Or it could have formed from a collision. • Irregular: unknown origin. Certainly captured objects, many irregulars, typically small, orbit at great distances and often on odd trajectories. All look to have similar compositions. • Trojan: Weird! Orbit the sun but are also gravitationally bound to Jupiter. They occupy positions called Lagrangian Points. Considered more "companions" of Jupiter. Do not orbit Jupiter.

13. Why are the rings orbiting Saturn's equator rather than spread in a haze about the whole planet?

• Related to the distribution of mass within Saturn itself. Being the least dense of all the planets plus a very rapid motion, it has a significantly bulged the planet at the equator and compressed it at the poles. • Thus the equatorial zones feels a greater gravitational pull than when it passes over the polar regions. Therefore the path of greatest orbital stability is a nearly circular one above the most massive sector of the planet, its equator.

2. What are asteroids and meteorites thought to represent? (e.g. age and material)

• Remnants of what could have been another planet.

6. What is the internal structure (and compositions of layers) of Uranus and Neptune?

• Rocky core o Highly compressed water • Liquid molecular hydrogen and liquid helium.

• What are Titan's dunes composed of?

• Sand dunes not too unlike those of Earth. Crystalized methane.

11. Are meteorites hot when they land? Why or why not?

• Seldom are hot because the atmosphere acts as a brake and reduces the meteorite's velocity. • Frequently they are cold when they reach Earth, this is because the melting phase only lasts a couple of seconds which does not allow enough time to conduct heat into its interior

14. Many meteors are destroyed in the atmosphere before they reach the Earth's surface - what kinds of meteors (size, speed) are more likely to survive?

• Smaller pieces have a higher chance of survival. Suffering less heat and ablation at smaller velocity. • -Larger meteors with slower speeds will survive more frequently because they will encounter the least resistance

14. What is an asteroid family? When two asteroids of unequal size collide, will the fragments come from the larger body or the smaller one?

• Smaller projectile experiences far greater stresses than the larger target body. Resulting pulverization or melting of the smaller projectile means that only one asteroid forms the majority of observable fragments resulting from the collision.

8. What are the possible sources of micro-meteoroids (a.k.a. interplanetary dust)

• Smallest meteoroids in the solar system. Composed of silicate minerals. Solar system must sweep them out, so there has to be a source to replace those continually lost. • Asteroids are one source and comet's trail.

5. What is unique about Uranus's rotation, what caused this and how does this affect its seasons?

• Something big pushed Uranus over on its side. Large planetoid possibly. • It gets 43 years of continuous sunshine followed by 42 years of darkness.

2. How do we know that it is hot? Why does is have a high heat flow (what is the internal heat engine)?

• Strong winds produce the pattern, but the planet's heat is the driving force of the circulation. • Infrared observations show that Jupiter emits 1.7 times as much energy as it receives from the sun. It's weird interior was responsible for a very high heat flow. • The heat is not decay of radioactive elements within the planet - that must be occurring, but not nearly at the rate necessary to produce the temperature we record. Astronomers theorize that the source of Jupiter's excess energy is the slow compaction of the planet - atoms of hydrogen and helium move as gravity very slowly pulls them into a more compact configuration, and that motion creates heat.

You do not need to know how to calculate estimates for planetary orbits using the Titius Bode Law, but please be aware that such a law exists - what does it allow us to predict?

• Take the simple mathematical series 0, 3, 6, 12, 24, etc. Note that each successive number is double the previous one. • Add 4 to each of the above, getting: 4, 7, 10, 16, 28, etc. • Now divide each of the above numbers by 10 to get: 0.4, 0.7, 1.0, 1.6, 2.8, etc. These are the predicted planet spacings in Astronomical Units.

19. What conditions prevent life on the planet in the inner solar system (terrestrial planets) versus the outer solar system (gas giants)?

• The Moon is airless. Never had liquid water. • Mercury is airless and cannot have liquid water on its surface for long periods of time. • Venus has some traces of water vapour in the atmosphere, but the surface is much too hot for liquid water to survive. • Inner solar systems are too hot and the outer solar systems seem too cold.

16. Outline the evidence that suggests the material in Saturn's rings is young.

• The apparent uniformity of material in the rings (to Voyager's cameras, they seemed to have about the same density of particles of ice everywhere). • The fact that the ice blocks were very reflecting and fresh looking; there was almost no dust on their surfaces, suggesting they could not have been around too long. • The theory that water ice in the near-vacuum of space would deteriorate over time by sublimation. In fact, Cassini has detected exactly that: a massive eruption of atomic oxygen spewed into a huge cloud on the dark side of Saturn's rings just as the craft was preparing to enter orbit. While such a concentration was a big surprise, the detection of oxygen atoms was not (see previous point). Hydroxyl ions had already been detected earlier (actually all the way from the Hubble Telescope).

7. What are the 2 main components of Saturn's atmosphere?

• The composition of Saturn's atmosphere broadly reflects the composition of Saturn's interior. About 91% of the atmosphere is hydrogen, 6% is helium, and the rest consists of nitrogen, oxygen, carbon, and a few compounds including water, ammonia, and methane. In the very outer layers are small quantities of hydrocarbons, including acetylene, ethane, propane and methane.

11. Does Pluto have an atmosphere? How is it created?

• The daytime temperature of about 50 K (-223°C) is enough to vaporize some of the nitrogen and carbon monoxide and a little of the methane to form a thin atmosphere around Pluto.

11. Although Uranus and Neptune have similar atmospheres, Neptune is a bit hazy - why?

• The division between stratosphere and troposphere appears unusually hazy. That haze is thought to be a rather high concentration of organic molecules, again caused by the breakdown of methane by sunlight. Being so much further from the Sun than other planets, it was unexpected for such a high concentration of organic material to be found.

7. What is Planet X?

• The large planet that Lowell was actually hunting but instead found Pluto and it hasn't been discovered yet

18. When looking for life elsewhere in the solar system or universe why do we look for liquid water?

• The most important requirement is the presence of liquid water, not only as part of the chemical reactions of life, but also as a medium to transport nutrients and wastes within the organism. Also, it seems that life on Earth began in the oceans and developed there for nearly 4 billion years before it was able to emerge onto the land. Certainly, any world where we hope to find life must have liquid water, and that means it must have moderate temperatures.

6. Describe the technique of blink-comparison that was used to originally find Pluto

• The observatory director set Tombaugh to work photographing the sky along the ecliptic in the general vicinity of the predicted position of the planet. Tombaugh obtained pairs of 14 x 17-inch glass plates exposed two to three days apart. To search a pair of plates, he mounted them in a blink comparator - a machine that allowed him to look through a microscope at a small spot on one plate and then at the flip of a lever see the same spot on the other plate. As he 'blinked' back and forth, the star images did not move, but a planet would have moved along its orbit during the two to three days that elapsed before the second plate was exposed. So, Tombaugh searched the giant plates, image by image, looking for an object that moved. A single pair of plates could contain 400,000 star images. He searched pair after pair and found nothing.

15. What is the difference between a prokaryote and a eukaryote?

• The oldest fossils are classified as prokaryotes: poorly defined, simple, single-celled organisms, lacing complex internal structures such as a nucleus. • Eukaryotes developed from prokaryotes, but they are larger, more organized cells (nucleus), and live by respiration. Which means they have a need for oxygen to use for energy.

2. Why was Pluto demoted from planet status?

• The reason for the reclassification was simply that more and more objects almost identical to Pluto were being discovered, and we could eventually be talking about 50 planets.

20. Which of Saturn's satellites looks like the Death Star from the Star Wars movies?

• The satellite is just too small to have a significant internal heat generator - so where does the heat come from? The best answer is that the frictional 'kneading' of the satellite by the tidal attraction of adjacent Saturn is to blame (much like the heat provided to Io by Jupiter's tidal affects). Also, there's a wobble to the satellite. Together, the kneading and the wobble should produce just enough heat to make liquid water.

26. Astronomers have been searching for other planets that might have the right characteristics for life - have they found many potential candidates?

• There could be as many as two billion Earth-sized planets orbiting within the habitable zones of stars within the Milky Way galaxy. • This is an extrapolation, based on the statistics of Kepler's finds over the preceding four years, but the widely-touted implication is that about one in five of the Sun-like stars should be orbited by an Earth-sized planet within a habitable zone!

4. Why did scientists crash the Galileo spacecraft into the surface of Jupiter? What did we learn during this descent?

• There was some possibility that it could contaminate one of its own discoveries - the icy crust of the satellite Europa. • We detected extremely high winds and intense turbulence and learned about the composition of Jupiter's atmosphere

3. Why did the asteroid belt form between Mars and Jupiter?

• They originally didn't. Formed throughout the inner solar system. Placed them as close as 30 million km from the sun. Probably sufficient refractory minerals forming as far out as Jupiter. When planets began to form, gravitational forces changed that geometry dramatically. Asteroids did not meet this fatal end were commonly flung outward ending up within the influence of Jupiter - which has a large mass and therefore gravity affects the motions of small bodies anywhere close to it.

7. Describe how the process of natural selection results in the evolution of species.

• To adapt to the changing environment of Earth. Which, would drive extinction. DNA must therefore change. Natural selection is merciless to the individual, but it gives the species the best possible chance to survive in a changing environment. • Another way this can occur is through damage to reproductive cells from exposure to radioactivity such as cosmic rays or natural radioactivity in the soil. In any case, genes produced in offspring that contain mutation(s) are called mutant genes, and often the individual is called a mutant.

9. Explain the 3 levels of cloud formation on Jupiter and Saturn. On which planet are the clouds higher in the atmosphere and why?

• Upper layer has relatively high content of ammonia, second layer is ammonia hydrosulfide, and the innermost layer is water clouds. • Temperatures are deeper in Saturn's cold atmosphere, but the clouds form at the same temperature on both planets.

8. Do these planets have magnetic fields? What creates them?

• Uranus' magnetic field is about the same of Saturn (close to Earth's). • Generated from a spot about 1/3 away from the southpole. Current explanation is that the generator has to do with rotational motion between the ammonia and water ocean layers of the planet. • Neptune is a bit less than half as strong as Earth's. • As in the case of Uranus, the field is probably generated by the dynamo effect acting in the conducting fluid mantle. The magnetic field itself is weaker than those of the other giants. Auroras were confirmed near the magnetic poles but are a bit weak.

8. Is Pluto always farther from the Sun than Neptune? Why or why not?

• Usually the farthest from the Sun. Pluto is quite elliptical. Pluto was closer to the Sun than Neptune. Every 248 years it swings into orbit within Neptune.

13. Give an example of the kinds of features the spacecraft Dawn has observed on large asteroids.

• Vesta has a metal-rich core that is approximately 220 km in diameter. Its tallest mountain is bigger than the largest mountain on Earth. Moved onto Ceres viewed presence of highly reflective sports within craters. Likely they are icy spots.

16. What is the main kind of ice on Charon?

• Water ice

1. Why are Uranus and Neptune considered "ice giants"?

• Water, ammonia, and methane are called "ices," which Neptune and Uranus have higher proportions of than hydrogen and helium "the gases."

1. What are the sources of meteorites that we have found on Earth? How representative of the sources are the samples?

• We have samples of the Moon, Mars, and of asteroids in our meteorite collection with advanced analytical techniques to unlock their many secrets. • Roughly 40 years ago during Apollo Moon program, astronauts collected 800 pounds of Moon rocks they understood that many of the meteorites they had previously collected on Earth were chips from the Moon.

3. Describe what we observe happening on Jupiter's surface. What energy is driving the turbulence in the atmosphere? How does this differ from how weather patterns are driven on Earth? What is the Great Red Spot?

• We have seen that Earth's magnetosphere produces auroras, and the same is true on Jupiter. Charged particles in the magnetosphere leak downward along the magnetic field, and, where they enter the atmosphere, they produce auroras 1000 times more powerful than those on Earth. The auroras on Jupiter, like auroras on Earth, occur in rings around the magnetic poles. • Swirling cloud belts are invisible to our eyes. In the clouds of Jupiter lies the largest ocean in the Solar System and it has no surface and no waves. • The belts and zones are the energy driving turbulence in the atmosphere. Each hemisphere has around 6 bands with winds blowing at very high velocities in opposite directions. This explains the extensive shear and turbulence at the boundaries between these regions (see the discussion following about the Great Red Spot). • On Earth, high and low pressure regions are bounded by high-speed wings, and the same is true on Jupiter. • The largest dark spot is the Great Red Spot, which has been in one of the southern zones for more than 330 years. Twice the diameter of Earth. Formed by rising gas carrying heat upward from deep below the clouds and creating a vast, rotating storm. • Weather patterns on Earth are driven from heat of Sun, but weather on Jupiter appear to be dominated by the interior.

11. What is the primordial soup?

• What we would call Earth back in time when the oceans filled with a rich mixture of organic compounds.

15. Do collisions of particles in the rings make particles larger or smaller? Explain.

• Within the rings, gentle collisions gradually grind down the larger particles. Meanwhile, the smallest particles tend to stick to one another and build into larger clumps through accretion. These actions have established equilibrium between the destruction of larger particles and the accretion of small ones into bigger ones. Observations from Voyagers 1 and 2 show that the largest particles are near the rings' outer edge, the zone of the least disruptive forces.

16. Why do we need ozone? How did life survive before there was enough oxygen in the atmosphere to create ozone?

• Without oxygen, we would not have an ozone. • Without it we would have no shield against harmful ultraviolet radiation. • Ultraviolet radiation breaks down amino acids, and so attacks the building blocks of life.

7. How does the magnetic field interact with the solar wind and what implications does this have for life (e.g. humans visiting the planet or alien life on the moons of Jupiter)?

• Would be deadly for humans, it is the equivalent of a billion chest x-rays. 100 times lethal limit.

5. If all the meteoroids and asteroids in the main asteroid belt coalesced, would there be an additional Earth-sized planet between Mars and Jupiter?

• Yes there would be two in the past, but not anymore.

• Does Titan have the ingredients required for life?

• Yes.

1. Why is it hard to view Saturn's surface?

• You'll require magnifying instrument with at least 20x to see the rings of Saturn. • Saturn is more remote from the warming influence of the sun, a thick high altitude haze layer shrouds the planet, giving it a very bland appearance.

8. Explain why the atmosphere has visible belts and zones (same as on Jupiter).

• Zones are higher clouds formed by rising gas, and belts are lower clouds formed by sinking gas. But the clouds are not very distinct on Saturn. Measurements from both Voyager space crafts told us that Saturn's atmosphere is much colder than Jupiter's - something we would expect because Saturn is twice as far from the Sun and receives only ¼ as much solar energy per square meter. • The atmospheres of Jupiter and Saturn are very similar once we remember that Saturn is colder. Saturn's cloud pattern is much more uniform in colour than that of Jupiter and with less distinct divisions.