Astronomy Test #2

True or false: we can determine the radius of extrasolar planets by observing when they transit in front of their host stars

True

5 stages of planetary evolution

1. Differentiation: Denser material sinks, less dense material rises; protocore forming 2. Cooling: Heat flows from the core outward and escapes at the surface; smaller planets cool faster 3. Cratering: Lots of leftovers from formation 4. Magma flooding: Magma, water, or other liquids fill in the lowlands (surface filled with magma) 5. Weathering: surface smoothed out, clouds

Basic properties of life:

1. Made of organic molecules: carbon based 2. Metabolism: energy transfer via digestion 3. Reproduction: create new versions of themselves 4. Mutation: life adapts and evolves 5. Sensitivity to environment: responds to the environment Life needs water

Explain why Mercury does not have an atmosphere but Earth does:

1. Mercury is much closer to the Sun than Earth is, so the atmosphere would be too hot and would evaporate 2. Mercury is much smaller than Earth, so its lower gravitational field can't hold an atmosphere 3. Mercury doesn't have a strong magnetic field to shield its atmosphere from the solar wind which is stronger because its closer to the Sun

Callisto description:

A ball of dead ice (me)

Mutation

A change in a gene or chromosome.

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

Craters

A large round pit caused by the impact of a meteoroid.

RNA

A single-stranded nucleic acid that passes along genetic messages

Tidal heating

A source of internal heating created by tidal friction. It is particularly important for satellites with eccentric orbits such as Io and Europa.

In which of the following ways is Io unique among the Galilean moons? A. It has a very high concentration of volcanoes B. It is strongly influenced by tidal forces from Jupiter C. It was first observed by Galileo D. Its orbital period is measured in (Earth) days rather than (Earth) months or years E. It is bigger than Earth's Moon.

A. It has a very high concentration of volcanoes.\

How could have life started?

After things cooled down, simple organic molecules began to form under the blanket of hydrogen. Those molecules eventually linked up to form RNA which helps to build DNA

Sort the following characteristics by whether they apply to all four terrestrial planets or not: plate tectonics an atmosphere a rocky crust the presence of one or more moons significant magnetic field

All terrestrial planets: a rocky crust Not All Planets: the presence of one or more moons an atmosphere plate tectonics significant magnetic field

Impact of life on the Earth's atmosphere:

Anaerobic bacteria converted carbon dioxide into oxygen, but the oxygen was absorbed by the sea and the ground. Then, the oceans became saturated and the amount of oxygen in the atmosphere increased (Great Oxygen Event GOE). After intense volcanism, eukaryotic cells dominated and converted oxygen into carbon dioxide. Then, the cambrian explosion happened in which "real life" started which caused a significant spike in atmospheric pressure of oxygen

Volcanism

Any activity that includes the movement of magma toward or onto planet's surface

Why do we think there was once water on Mars?

Apparently, smooth rocks from Mars were compared to typical streambeds on Earth and they were similar. Found sediment that matches a dry river/lakebed at the bottom of Gate Crater, angle of slopes exactly match sand dunes on Earth and the flows are not found on shallower slopes, radar maps have shown several large underground lakes beneath the South Pole and being underground prevents the water from vaporizing instantly and they are extremely salty so they do not freeze but not all astronomers agree because cold clay gives a similar signal

Sort each statement by whether it describes the atmosphere of Earth or of Mars: Atmosphere undergoes periodic planet-wide dust storms Atmosphere is mostly nitrogen Atmosphere is mostly carbon dioxide Atmosphere is too thin for surface water to be liquid Atmosphere contains water vapor that precipitates as rain Atmosphere contains oxygen because of biological processes

Atmosphere of Earth: Atmosphere contains water vapor that precipitates as rain Atmosphere contains oxygen because of biological processes Atmosphere is mostly nitrogen

What is the source of the oxygen in the Earth's atmosphere? Why?

Biological life: Photosynthesis

How life reproduces:

By copying their genetic material and passing it on to their offspring through DNA, a polymer that contains the "plans" for life and RNA, a simple polymer used by life forms to "read" the DNA's "plans"

Which two planets are the closest in rotational period? A. Venus and Earth B. Mars and Mercury C. Earth and Mars D. Mars and Venus E. Mercury and Earth

C. Earth and Mars

Earth does not show the patterns of belts and zones seen on Jupiter. What is the principal reason for this difference? A. Jupiter has more mass and hence stronger gravity than Earth has B. Jupiter has more moons than Earth has C. Jupiter's rotation rate is higher than Earth's D. Jupiter's magnetic field is stronger than Earth's E. Jupiter is farther from the Sun than Earth is.

C. Jupiter's rotation rate is higher than Earth's.

What is the difference between an asteroid and a comet?

Comets are just icy asteroids

Sort the following features to identify which are common to gas and ice giant planets, and which are not: faster than Earth rotation predominantly hydrogen greater than 20 moons strong magnetic field rocky core large ice particles in rings

Common Features strong magnetic field faster than Earth rotation rocky core predominantly hydrogen Not Common Features large ice particles in rings greater than 20 moons

Interior layers of a terrestrial planet from inside to outside:

Core at the center, mantle in the middle, crust on the outside

Rank the terrestrial planets by the ages of their surfaces, oldest to newest A. Mars, Mercury, Earth, Venus B. Mercury, Venus, Earth, Mars C. Venus, Mercury, Mars, Earth D. Mercury, Mars, Venus, Earth E. Mars, Earth, Venus, Mercury

D. Mercury, Mars, Venus, Earth

Genes

DNA segments that serve as the key functional units in hereditary transmission.

Geological activity of Mars

Dry and dusty, evidence that Mars had liquid water in the past and currently has seasonal liquid water (controversial) and currently has subsurface water (new), northern hemisphere covered by volcanoes and lava plains with some erosional features, southern hemisphere covered by ancient craters and some erosional features, evidence of past volcanism: largest volcano in the solar system, massive cliffs, giant canyon may suggest tectonic stresses, polar ice caps- lots of water and carbon dioxide, regions with lots of craters indicating old age and lack of volcanism

What is the difference between an asteroid and a dwarf planet?

Dwarf planets are asteroids that are large enough to be spherical

Why did Venus end up so much hotter than Earth?

Earth is just far enough away from the Sun for the temperature to be low enough to allow water to condense to the oceans (Goldilocks zone) Carbon dioxide dissolves in water Venus has no magnetic field and therefore no protection from the solar wind, so most of the water molecules in Venus' atmosphere were destroyed before they could condense into water

Which moons may harbor life?

Europa: Deeper oceans than Earth give a high possibility of life in them Titan: Atmosphere and rivers/lakes of liquid methane lead to the hypothesis that life could exist in this liquid methane similarly to how some life on Earth lives in water Io: Hypothermal vents: we discovered life that lives around hypothermal vents on Earth, so the same might be true for Io

Geological activity of Venus

Extremely high temperatures, no plate tectonics but tectonic forces have fractured and twisted the crust, current volcanic activity, impact craters are present but relatively rare, geological activity is similar to Earth because they are the same size large enough to retain interior heat, volcanic outgassing of water and carbon dioxide should have happened to both planets early in their history which caused the greenhouse effect on both planets

True or false: a spacecraft traveling through the asteroid belt has a high risk of colliding with an asteroid

False

True or false: the rocky planets are found close to the Sun because heavier material sunk towards the Sun during the formula of the solar nebula

False: heavier material did not "sink" towards the Sun- the planets are rocky there because gas could not condense that close to the Sun

True or false: Mars has been a dry and dusty planet for it's entire history

False: we have strong evidence that Mars used to have both liquid water and an atmosphere

Rank the terrestrial planets in order of their cooling rates from fastest to slowest: Earth Mars Venus Mercury Why?

Fastest Mercury Mars Venus Earth Slowest The rate of cooling depends on the ratio of the surface area to the volume of the planet. Larger planets have more heat than smaller planets and thus stay hot longer. Mercury is the smallest and has the fastest cooling rate followed by Mars, Venus, and Earth

Order the stages of planetary formation from first to last Cratering Differentiation Weathering Cooling Magma flooding

First Differentiation Cooling Cratering Magma flooding Weathering Last As planets accrete material, they go through a process of differentiation as more dense materials are pulled to the center and less dense materials stay above them. This forms a protocore that heats up because of friction. They then go through a period of cooling followed by cratering during the heavy bombardment period. Craters are only left on a solid surface, so the planet had to cool before cratering could occur. Because of the cratering, magma flooding occurs and smooths out the surface. After that, the planet can have weathering, which continues to change and shape its surface.

What's the largest moon in our solar system?

Ganymede: evidence of past geological activity, but appears inactive today

If we discovered a planet with very few either large or small craters, what would we conclude? Why?

Geological processes must have erased the craters: forces like erosion, volcanic activity, and tectonic plate movements alter surfaces

Why does one planet in our Solar System orbit backwards?

Gravitational interactions between internal parts of the solar system (planets, moons, asteroids, etc) or external parts (another star)

Order the following planets by their equilibrium temperature from hottest to coldest: Saturn Neptune Earth Uranus Jupiter

Hottest Earth Jupiter Saturn Uranus Neptune Coldest The farther a planet is from the Sun, the less energy it will absorb and the colder its equilibrium temperature will be. From the list, Earth is the warmest at 279 K, next is Jupiter at 124 K, then Saturn at 90 K, Uranus at 64 K, and finally Neptune at 51 K.

Crust

The thin and solid outermost layer of the Earth above the mantle

Interior layers of Jupiter from inside to out:

Inside Rocky material Liquid metallic hydrogen Molecular hydrogen

Why did the Jovian planets form father out from the Sun, whereas the rocky planets formed closer in?

It was too hot for gas to condense near the Sun from the Solar Nebula. This was possible outside the frost line, so the planets out there are predominantly gas

Interior structure of gas planets differences:

Jupiter and Saturn: Liquid hydrogen, metallic hydrogen: probably a liquid, could be a solid, but it conducts electricity and can create a large magnetic field. Higher pressures and temperatures force hydrogen into liquid and "metallic" forms Uranus and Neptune: Interiors have hydrogen compounds: water, methane, and ammonia; icy/slushy ammonia and methane with a rocky core

Magnetic fields of gas giants:

Jupiter: extreme magnetic field driven by the metallic hydrogen in its core; strongest planetary magnetic field The other gas giants all have magnetic field as well, smaller than Jupiter's but larger than Earth's Saturn: like Jupiter, the presence of metallic hydrogen in its core creates a large magnetic field. Only visible in UV. Can't take a picture of this aurora because Earth's atmosphere blocks UV light

Geological activity of Mercury

Large patches of craters which probably indicate rocks melted from impact; no evidence of large scale lava flows; Mercury is shrinking: peculiar cracks are forming as the crust bends; ice water at the poles where the sun doesn't hit

extremophiles

Life on Earth that live in extreme environments Ex: Hydrothermal vents: hot springs a mile below the surface where the sun does not shine. Chemosynthesis instead of photosynthesis

Saturn's atmosphere

Like Jupiter, mostly hydrogen and some helium. Slightly different in the sense that it contains hydrocarbons (methane, etc.) Fewer colorful bands, most likely more ice in atmosphere which makes it look hazy. Wind speeds are enormous due to Saturn's incredibly fast rotation. Saturn rotates so fast that it's oblate (squished)

Greenhouse effect

Natural situation in which heat is retained in atmosphere by carbon dioxide, methane, water vapor, and other gases

Which of the following occurrences would be associated with an orbital resonance between a ring particle and a moon orbiting Saturn? regular, periodic gravitational tugs between a ring particle and a moon a moon being torn apart by tidal forces gaps in the rings a ring particle maintaining a circular orbit a moon being struck by a meteor

Linked to Resonance: gaps in the rings regular, periodic gravitational tugs between a ring particle and a moon Not Linked to Resonance: a moon being torn apart by tidal forces a moon being struck by a meteor a ring particle maintaining a circular obit

Rank the terrestrial planets from longest to shortest rotational period: Mars Earth Venus Mercury

Longest Venus Mercury Mars Earth Shortest

Why do different planets have the atmospheres they do? COME BACK TO

Mars has no atmosphere because as it cooled, it was stripped of its magnetic field which led to the solar wind stripping it of any atmosphere Mercury: small magnetic field leads to basically no atmosphere

How did the presence or lack of presence of magnetic fields affect the history of planets?

Mars: as the planet cooled, it was stripped of almost all of its magnetic field which led to the solar wind stripping it of any atmosphere. Without an atmosphere, Mars froze Venus: No magnetic field resulted in no protection from the solar wind so most of the water molecules in Venus' atmosphere were destroyed before they could condense into water Mercury: Small magnetic field Earth: Really the only terrestrial planet that has a significant magnetic field

Sort the following descriptions by whether they pertain to Mercury, the Moon, or both. surface has maria caused by past collisions and volcanic activity very large iron core highly cratered surface very little atmosphere inhospitable to biological life

Mercury very large iron core Moon: surface has maria caused by past collisions and volcanic activity Both: inhospitable to biological life highly cratered surface very little atmosphere

Atmospheres of each terrestrial planet (thick vs thin, dominant chemical compositions):

Mercury: Basically no atmosphere (some hydrogen and helium from solar wind) Venus: Extremely thick atmosphere; 200,000 x the amount of carbon dioxide than the Earth's atmosphere as a result of having no water to absorb carbon dioxide; lead to a runaway greenhouse effect Mars: Extremely thin atmosphere, low-pressure atmosphere Earth: Composed of primarily nitrogen with some oxygen and other gases, driven by moving charged particles in the Earth's hot, molten, metallic core

Callisto Moon of: Physical characteristics: Distinctive features:

Moon of: Jupiter, farthest away Physical characteristics: Very cratered, red, shiny, lots of ice; more ice, less rock Distinctive features: MIGHT have subsurface oceans

Io Moon of: Physical characteristics: Distinctive features:

Moon of: Jupiter; closest to Jupiter Physical characteristics: Volcanos, smooth and cratered surface, red and yellow (due to sulfur which gives off red and orange tint) Distinctive features: Volcanos- why? Tidal heating from Jupiter

Europa Moon of: Physical characteristics: Distinctive features:

Moon of: Jupiter; second closest to Jupiter Physical characteristics: Reflective surface, scratch marks from impacts with ice Distinctive features: Oceans underground, massive oceans bigger than Earth

Ganymede Moon of: Physical characteristics: Distinctive features:

Moon of: Jupiter; third closest Physical characteristics: Kinda like our moon, SOME ice, but more rocky than icy Distinctive features: Largest moon in solar system; bigger than Mercury MIGHT have subsurface oceans

Triton Moon of: Physical characteristics: Distinctive features:

Moon of: Neptune Physical characteristics: Ice and rock, smooth and cratered surface, young=smooth old=cratered Distinctive features: Orbits Neptune backwards most likely because it was already moving in that direction and got sucked into Neptune's orbit that way, very thin atmosphere that varies with season

Titan Moon of: Physical characteristics: Distinctive features:

Moon of: Saturn, closest Physical characteristics: Purplish from methane throughout atmosphere, kind of looks like Mars, rivers and lakes of methane, ONLY PLACE IN SOLAR SYSTEM WITH LIQUID, mushy, frozen surface of methane or ethane Distinctive features: Thick atmosphere made of methane and hydrocarbons. Only moon besides our own that we have landed on

Enceladus Moon of: Physical characteristics: Distinctive features:

Moon of: Saturn, second closest Physical characteristics: "Little Europa," craters, cracks, frozen, nearly 100% reflective, surface almost entirely water ice Distinctive features: Cryovolcanos: volcanos of frozen water, possible subsurface ocean with hydrothermal vents?

Darwinian Evolution

Mutation: Randomly through errors during replication or altered via exposure to radiation Migration: Breeding between variations of a population Genetic Drift: Some traits in a population became randomly more present Natural selection: Genetic traits make individuals more likely to survive

Why are Uranus and Neptune blue/green while Jupiter and Saturn are red/yellow?

Neptune and Uranus have methane in their atmosphere: methane gives off a bluish tint

Techniques for searching for life; the Drake Equation

Number of technological civilizations in the galaxy= number of stars in the galaxy x number of planets around each star x fraction of planets in the habitable zone x fraction of planets in habitable zones that evolve life x fraction of planets with life where life evolves intelligence x fraction of a star's lifetime in which a civilization exists

Explain why the figure of the distribution of asteroids in the Asteroid belt relative to their orbital radius shows gaps in this distribution

Orbital resonance with Jupiter

Four planets that formed at the same time have equal density and the following radii: planet W: 2,000 km planet X: 2,500 km planet Y: 2,700 km planet Z: 5,000 km Ignoring any other factors, which planet would be expected to cool fastest? A. Planet W, with radius 2,000 km B. planet X, with radius 2,500 km C. There is no way to know. D. planet Z, with radius 5,000 km E. planet Y, with radius 2,700 km

Planet W, with radius 2,000 km smaller planets have a larger ratio of surface area to volume than larger planets and will cool more quickly

Proteins

Polymers made up of amino acids- different combinations of the 20

Erosion

Processes by which rock, sand, and soil are broken down and carried away (i.e. weathering, glaciation)

Weather patterns on gas giants:

Reddish brown bands of falling air, white bands of rising air. Bands are created because of higher rotation rates that stretch out wind patterns Clouds are water, ammonia, and methane Planets are typically spinning very fast which creates intense storm activity. Ex: cyclone at Jupiter's north pole surrounded by 8 other cyclones Jupiter has the most intense weather. Convection in the atmosphere

"Life cycle" of a planet's rings and what they look like they do:

Rings are made up of reflective ice boulders (ice and dust). They orbit the planet like little planet's in accordance with Kepler's third law. Presence of "gaps" either due to a Moon gathering up the ice or gravitational tugs from other moons. A gap moon creates ripples as its gravity nudges particles that orbit faster than the moon (inside the gap) or slower (outside the gap) Rings are transient: collisions between ring particles are common and gradually grind down the particles until they disappear. Therefore, the rings must be constantly fed with new material presumably via impacts on surrounding moons. 1. Tidal forces near the planet prevent small moonlets from combining into larger moons 2. Moonlets are occasionally disrupted by by impacts 3. Ongoing small impacts blast off dust and debris to form the rings

Most estimates suggest that Saturn's rings are actually older than our estimates- explain this contradiction

Saturn's rings are continuously supplied by material from Saturn's smaller moons

Saturn/Jupiter vs Uranus/Neptune:

Saturn/Jupiter: Liquid hydrogen, metallic hydrogen: probably a liquid, could be a solid, but it conducts electricity and can create a large magnetic field. Higher pressures and temperatures force hydrogen into liquid and "metallic" forms Uranus/Neptune: Interiors have hydrogen compounds: water, methane, and ammonia; icy/slushy ammonia and methane with a rocky core

What factor has the greatest effect on a planet's level of volcanic activity? Why?

Size: Smaller planets cool down too quickly for their interiors to sustain volcanic activity

Core

The central part of the earth below the mantle

The solar cycle is the 11-year long period in which the surface of the Sun goes from peak Sunspot activity to minimum Sunspot activity. What causes this cycle? Why?

The changing magnetic field of the sun: the magnetic field is constantly cycling between winding up and winding down.

How do tidal forces affect Jupiter's moons?

The farther away the moon, the less geological activity there is

Mantle

The layer of hot, solid material between Earth's crust and core.

Ages of craters vs geological activity

The more cratered the surface, the older it is. geological activity leads to altering of the surface, so craters affected by geological activity are smoothed over

The habitable zone

The region around a star in which water can be liquid Liquid water is used by life on Earth as a catalyst and solvent

Convection

The transfer of heat by the movement of a fluid

Why are sunspots darker than the rest of the surface of the Sun? Why?

They are colder than the rest of the surface: they form at areas where magnetic fields are particularly strong. These magnetic fields are so strong that they keep some of the heat within the Sun from reaching the surface.

How is it possible for Io to have volcanic activity when it's so small?

Tidal heating: Jupiter's extreme mass and Io's elliptical orbit cause extreme tidal forces to flex the Moon and heat the interior

Which moon in our solar system has an atmosphere?

Titan (Moon of Saturn)

What happened to the water on Mars?

Two possible reasons: 1. Mars is too small to "hold on" to an atmosphere through gravitational interaction 2. An active interior probably meant a magnetic field, but as soon as the planet cooled, the magnetic field almost totally vanished and the resulting solar wind stripped the planet of any atmosphere, without an atmosphere, Mars froze

The spectrum of an exoplanet reveals significant amounts of methane with smaller amounts of ammonia. Considering this information alone, to which planet in our Solar System might we expect the exoplanet to be similar?A. Earth B. Uranus C. Saturn D. Jupiter E. Mars

Uranus

Which planet is tilted on its side?

Uranus

Which body has the longest "day"? (A day is defined as the interval between the time at which a particular point on the body faces the Sun and the time at which the point faces the Sun again.) A. Venus B. Earth C. Earth's Moon D. Mercury E. Mars

Venus

Interior structure of gas planets similarities:

Visible clouds Gaseous hydrogen Core of rock and metals

Sort the Galilean moons by the type of liquids in their interiors (water or magma): Io Ganymede Europa

Water Europa Ganymede Magma: Io

orbital resonance

When two orbiting bodies exert a gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers.

Sort the following planets by whether they formed within the snow line or not. Recall that the snow line is based on what phase of matter water is found in. Mercury Earth Saturn Neptune Mars Venus Uranus Jupiter

Within the Snow Line Mars Earth Venus Mercury Outside the Snow Line Neptune Uranus Saturn Jupiter

amino acids

building blocks of proteins; a monomer used by organic life; only 20 of them including proteins

organic molecules

carbon-based molecules

Which of the following is not a source of heat in the interiors of the terrestrial planets? radioactive decay gravitational compression collisions from other bodies friction between atmosphere and surface differentiation

friction between atmosphere and surface

Polymers

long chains of molecules

Monomers

short chains of molecules

A caldera is which of the following? A. a channel dug by the glancing blow of an asteroid B. a depression that filled with lava C. a long ridge formed by planet shrinkage D. a crest formed by the meeting of two crustal plates E. the depression at the top of a volcano

the depression at the top of a volcano

Tectonics

the disruption of a planet's surface by internal stresses

runaway greenhouse effect

when a planet absorbs more energy from the sun than it can radiate back to space