Flashcards
Astronomy Test #3
Flashcards do conjunto (115)
- 1Could you distinguish between Earth and Sun-centered solar system models by observing Venus with a telescope?Yes
Galileo did this
Saw the phases - 2Why are the planets closest to the Sun more dense than those farther from the Sun?When formed a temperature gradient was present, more heavier solar material could solidify closer, lighter material wouldn't :. material availability
- 3What is the solar wind?charged particles from sun
- 4Where do asteroids come from?come from the formation of early solar system
- 5If Earth was more reflective (had a higher albedo), what would happen to its temperature?Sunlight would be reflected into space, wouldn't be absorbed therefore earth would be cooler
- 6What are the main constituents of Earth's atmosphere?Nitrogen and Oxygen
- 7Which of the following is not a characteristic of jovian planets?molten core
crust - 8How did Ptolemy's model differ from Aristotle's model of the universe?Aristotle perfect circles
Ptolemy was the deference in epicycles - 9Why are smaller terrestrial bodies such as Mercury or the Moon "geologically dead"?the radioactive decay has decreased to such a degree :. no longer molten (internal structure)
- 10At any given time, how many high tides are there on Earth?2 high tides
one on the moon side of the earth and one one the side facing the sun - 11What are Some of the features of Auroras?Due to magnetic field
occur in polar regions
due to solar wind coming in contact with the earth's atmosphere - 12Where do comets come from?Come from Kuiper belt (icy and rocky) or the Oort cloud ((pertubated) kicked out by being closer to Jupiter = rockier)
- 13What is the main reason that Venus is warmer than Earth?Runaway greenhouse effect
- 14Which of the following planets has the most oxygen in its atmosphere?Earth has most oxygen
- 15What are some of the features of Primitive meteorites?Early formation of solar system
Rocky - 16Jupiter does not have a large metal core like Earth. How can it have a magnetic field?Metallic hydrogen, acts like a metal :. causes magnetic field
- 17Why do the lunar highlands have many more craters than the lunar maria?Older
Maria's formed after large bombardment :. lunar highlands are smoothed out - 18Why do we think Mars was once warmer and wetter?Evidence of water, once had rain
water flowed on surface - 19How does Io get heated by Jupiter?tidal heating causes massaging effect
- 20Asteroids have the following features10s of metres to 100s of kms
Irregular shapes - 21Which of the following planets has the most dense atmosphereterrestrial: Venus
- 22What age does radiometric dating give for Moon rocks and meteorites?4.6 billion years
- 23What is the structure of Jupiter like?Core - rocky
Metallic Hydrogen
Predominant features
Clouds - 24Which of the following is not one of Kepler's laws of planetary motion?deferents and epicycles
select the option that is not these
1. The orbit of a planet around the sun is an ellipse with the sun at one focus
2. A line joining a planet and the sun sweeps out equal areas in equal times
3. The square of an orbital period (P) of the planet is proportional to the cube of the semi-major axis (a) of the orbit - 25Why do we think that the solar system formed from a rotating, collapsing gas cloud that ended up as a disk orbiting the Sun?All the planets orbit the Sun in the same direction
planets have right characteristics to have formed from a disk of mainly hydrogen around a young, hot Sun
Observations of Sun agree with the theory of a giant ball of mostly hydrogen generating heat by nuclear fusion in the core. - 26What do we think the composition of the solar nebula was?Hydrogen
Helium
Other
Planets and Sun are made out of these - 27Which bodies show evidence of a substantial atmosphere?Mercury - no
Venus - yes
Earth - yes
Mars - not really - 28What is the main source of the original atmospheres of the terrestrial planets?Volcanic outgassing
Original Atmospheres - 29What are the most common elements in the atmospheres of the jovian planets?Hydrogen
- 30Meteorites come from where?Debris of comets and dust
- 31Suppose a comet had a very eccentric orbit that brought it quite close to the Sun at closest approach (perihelion) and beyond Mars when furthest from the Sun (aphelion), but with an average distance of 1 AU. How long would it take to complete an orbit and where would it spend most of its time?1 year
Further out beyond Mars - 32If there was no greenhouse effect, how would Earth be different?Cooler
- 33What is the shape of a planets orbitNearly circular
- 34What are terraeHighlands on the moon's surface
- 35What happens with the earth and the moons tidal wavesSide closest to the moon attracted stronger -> gives a bulge of water on the near side
Side farthest from the moon is attracted least -> leaves a bulge of water of the far side
This gives a double sided tidal bulge - 36What are some other ways that solar wind can make its presence knownComet tails are pushed away from sun
Heliopause maybe ~100AU away - 37What is the ion tail in a cometIonised atoms from coma
Accelerated by solar wind; pointed away from sun
Straight but does exhibit filamentary structure which can change daily
Bluish colour
Up to 1AU long - 38What is the scale of the outer regions of the solar system?Planetary System = ~40AU radius
Heliopause = ~100AU radius - 39Where in the Milky Way are we locatedIn the Orion Spiral Arm
- 40How many exoplanets have we found thus farOver 3,498 exoplanets
- 41What is the composition of the sun74% Hydrogen
25% Helium
1% other - 42What is the direction of rotation of the planetsClockwise apart from Venus which spins backwards and Uranus which spins on its side
- 43What is the plane that all planets orbit along called and are all orbits the same?Ecliptic plane
Planets orbit is almost the same - 44What is the approximate tilt of the planets axis~30 degrees
- 45What are the similarities between Venus and MarsSimilar topography
Similar size
Formed similarly to earth - 46How long is the rotation period of Jupiter?Similar to the sun, the colourful belts of Jupiter rotate different ways I.e. left, right, left etc.
- 47What do the colours on Jupiters surface represent?Different chemicals, temperatures and atmospheric height differences that the chemical clouds are forming under
- 48How big is Jupiter's red spot?20,000km x 10,000km
- 49What determines a shape of an objectIf an object is warm and cools down slowly, it's gets a round spherical shape
If an object cools quickly it forms an abnormal shape - 50What are the characteristics of Saturn's moon: TitanRain, clouds and sleet are made out of methane and ethane
It's cool enough that methane could be a liquid or a gas
Has liquid hydrocarbons
It has waves like our oceans do - 51How can we determine the chemical composition of a planetUsing the colour spectrum once sun is behind the planet (concept for exoplanets is the same)
- 52What is the density of water on earth in comparison to other planets massEarth's water = 1,000kg/m3
Mercury = 5x the density of water
Jupiter = less density of water
Saturn could float on water, that is if you find an ocean big enough - 53How dense is the asteroid beltThinly spread, if all matter in the asteroid belt was clumped together it would form a small moon. Definitely not like Star Wars
- 54Where does solar and cosmic radiation come fromSolar from the sun
Cosmic from other sources in space - 55Where on earth are the auroras located and what are the aurora areas calledIn the North & South poles
Northern = Borealis
Southern = Australis - 56What is the key to Ptolemy's model: the epicycle and the deferentA planet moves in a small circle otherwise known as an epicycle
The centre of the epicycle moves along a larger circle called a deferent which is approx. centred on earth - 57What are inferior planets and elongationOrbits that are smaller than earth's
The angle between the sun and a planet as viewed from earth - 58What are superior planets and oppositionOrbits that are larger than earth's
Planet is in opposition part of the sky to the sun (visible at night) - 59What is an ascending node?The point where'd the planet (moving in it's orbital period) crosses the ecliptic from south to north
- 60What is a descending node?The point where the planet crosses the ecliptic from north to south
- 61What is the sequence of events from the Big Bang?BIG BANG - H, He, Li, Be,- galaxy formation - nucleosynthesis in stars- new elements - generations of stars - big stars create supernovas - interstellar medium enriched with heavier elements I.e. Fe, C, N, O etc
- 62What happens at hotter temperaturesMore isolated atoms I.e. H and Fe
Ionisation of atoms (if hot enough) e.g. H+ or Fe++
Plasma - ionised gas/atoms - 63What happens at colder temperaturesAtoms form molecules i.e. H2, NH3, CO, N2, H2O
Materials solidify I.e. ice, dust and rock
Form metals, metal oxides, silicates erc - 64What does our galaxy containCentrally located nucleus of millions of stars
Spiral arms - lanes of interstellar gas, dust and young stars
Interstellar medium ion between stars - 65What does the interstellar medium containMolecular clouds - cool gas and dust
Inter cloud gas - region between clouds (less dense and warmer)
Bubbles of hot gas - due to supernovas - 66What are the characteristics of the giant molecular cloudsWeak magnetic fields
Different sizes and masses
Cold temperatures 10-50K
Mainly molecular hydrogen (H2)
Perhaps 1% microscopic dust and ice
Contain small dense regions - 67Case study: Bok Nebula "Barnard 86"Core remnant of a molecular cloud
410 light-years
12,500AU
16K
2x greater in mass than the sun
Pressure at boundary = 0.0025nPa
Clouds like this can form isolated low mass stars - 68Where does most of the mass in our solar system lieIn the sun, angular momentum is in the planets
- 69What was the sequence of events in the formation of the solar systemEnriched molecular cloud compression - cloud core of new star system - solar nebula - matter attracted to nebula - Protosun develops - gas, dust, ice form disk - planets established - nebula with small residual rotation - core contracts (200,000AU-50AU) - rotation of nebula increases - nebula flattens out
- 70Why are there different types of planets1. Solar nebula had radial temperature gradient
2. Materials condensed into solids at different temperatures - 71What are the rock forming substancesSilicates, metals etc
Solid at night temperatures
Solid nearly everywhere in solar nebula - 72What are the molecular compounds like waterWater, methane and ammonia
Solid at low temperatures ~100-300K
Not much solid in the inner solar system
When solid - called ices
More ice than silicates
Hydrogen molecules and helium never solidify in the nebula - 73What are the different temperature gradients in the different zones of the solar nebulaInnermost (terrestrial) warm, 300-1200K
Metal/ silicate materials solid if not too close to protosun
Any idea vapourised and not readily accreted
Intermediate (Jovian) cold, ~50-200K
Metals, silicates, and ices stable solids
All available for accretion
Outer (cometary) colder, <30K
Metal, silicates, ices stable solids
Material is too sparse - inhibits planet building
Rocky/icy planetissimals - comet nuclei (Kuiper Belt) - 74What is the planet building systemAccretion of planetissimals to form planets
A. 100 planetissimals (~1km size) orbiting the sun
B. After 30 million simulated years have 22 protoplanets
C. >100 million years - some well established planets - 75What is the consolidation stageInner zone
Planet sized ball of metal, oxides and silicates
Intermediate zone
Growing planet sized ball of metal compounds, silicates and ices
Grow larger than earth due to ice
Planet cools and shrinks
Outer zone:
Icy planetissimals (~kms in size) dispersed thinly to accrete efficiently
Millions of objects - 76What is the cleanup stage1. Radiation pressure
2. Solar wind
3. Mopping up of debris by planets
4. Close encounters with other planets - 77What is earth's internal structureCore:
0-3500kms
Ni & Fe
Mantle:
Liquid iron alloy outer core
Solid iron alloy core
Crust:
Low density rock
Floats on mantle
Thinner under oceans ~10km thick - 78What is mercury's internal structureCore:
75% of planet (diameter)
Mantle
600 km thick
Small magnetic field - some molten core - 79What is oblatenessMeasure of how much a flattened sphere differed from a perfect sphere
- 80What does oblateness depend onSize of planet
Rotation rate
Matter planet is formed from
How the matter is distributed inside the planet - 81What is the system of heating of the planets for rocky bodiesObject (like earth) entirely molten
Differentiation creates a layered structure
Heavier material sank to the core
Lighter material floated to outer layers
Cooling over time
Outer layers solidify first
Larger bodies cool slower than smaller bodies
Need liquid conducting core - 82What is the internal structure of JupiterCore:
Rocky inclination I.e. Fe, Ni & Si
High density
Liquid metallic hydrogen
Molecular hydrogen
Colourful band patterns in the top 100kms
Low density
H and He abundant
Strong magnetic field - 83What is the internal structure of Uranus and NeptuneRocky core
Mantle compressed water with some ammonia
Layer of liquid molecular hydrogen and liquid helium with a small amount of methane + clouds above - 84What are the moons physical characteristicsDiameter: 3476 km
Gravity: ~1/6 earth
Sidereal period: 27.332days
Average surface temperatures: 403 K (day) 93 K (night)
Albedo: ~0.1
Angular size: ~1/2 degrees
Average density: 3340 kg/m3 - 85What are Maria'sLowlands on the moons surface
- 86What are the types of rocks found on the surface of the moonIgneous, meaning that the surface of the moon was once molten.
Basalt: found in the mare, dark, typical of cooled lava
Anorthosite: found in the highlands, light colour - 87What is the composition of the moonRegolith: fine powder and rock fragments covering the moon's surface;
- 88What is the structure of the moonMare on moons crust
Crust - solid, brittle, less dense material
Solid upper mantle
Non-rigid inner mantle
Core: iron rich - 89What is the moon doing annuallyReceding from earth at ~ 4cm/yr, this slows the earth's orbit by 0.002 seconds per century
- 90What does the height of tides depend onHeight of high tides vary due to the effected of sun's gravity
Spring (larger)
Neap (weaker) tides - 91What are planetary surface temperatures due toSolar heating (depends on distance from planet to sun and its albedo)
The surface temperature of the planet also affects the planets atmosphere - 92What is albedoThe fraction of radiation reflected back into space
E.g.
Albedo 1 ~ all radiation reflected
Albedo 0 ~ no radiation reflected - 93What happens if an object absorbs energy at a higher rate that it can radiate awayIt only gets hotter. As the object gets hotter, it radiates more.
- 94What happens if sunlight reaches a planet with no atmosphere vs with an atmosphereNo atmosphere: infrared radiation escapes into space
Atmosphere: some infrared radiation is absorbed in the atmosphere whilst the rest escapes into space. This causes the planets temperature and atmosphere to rise - 95What are the differences between terrestrial and Jovian planetary atmospheresMinimal (compared to terrestrial planets)
Implies... less processing of the atmosphere - 96What are the levels in the earth's atmosphere?Troposphere - 0-12km, 80% of atmospheric mass, weather zone, clouds & pollution
Stratosphere - ~12-50km, ozone region, heating of region
Mesosphere - 50-80km
Thermosphere - ~80+km, thin, windiest zone - 97What are the levels in venus' atmosphereLower atmosphere - hot, dense, clear
Cloud layer - 3 separate levels, lower level most opaque, thin haze exists both above and below cloud layer
Cloud composition - sulphuric acid droplets, no rain on surface, high temperatures, acid and sulphur based components - 98What are the planetary atmospheres of Uranus and NeptuneUranus - 2% methane (greenish blue), featureless (no water or ammonia), 98% rotation axis tilted, global circulation issue?
Neptune - more dynamic than Uranus, high clouds, faint belts & zones, internal heating driven - 99What is the source of solar wind and what are its characteristicsThe corona
Not dense
Plasma (charged particles) that becomes solar wind - 100What are the characteristics of cosmic raysNon-solar source of radiation in the solar system
Composition: ~87% protons, ~12% alphas
Particle numbers are less than a solar flux wind
Energy of the particles are greater than solar winds - 101What are the characteristics of earth's magnetic shieldShock front: Where the solar wind is slowed to subatomic speeds
Magnetopause:
Where the pressure of earth's magnetic field balances the solar wind pressure - 102What are the characteristics of Jupiters magnetosphereHuge: envelops the orbits of several moons
Solar radiation gets trapped and emits synchrotron radiation at radio wavelengths
Lower energies - radio
Higher energies - x-rays - 103What happens with auroras in terms of planets without an atmosphere e.g. VenusSolar wind impacts directly on the upper atmosphere ionising the gas
Shock region develops where the solar wind is slowed and interacts with the atmosphere - 104What happens with auroras on Mercury and MarsMercury - weaker field 1% that of earth's, similar process to earth but smaller scale, too weak to trap radiation
Mars - no globular magnetic field but does have some magnetised regions in its crust - 105What are cometsFew kms in diameter
Irregular shapes
Loose collection of ices, water, methane, ammonia and carbon dioxide, and rocks
Low albedo
Covered in black material
Crust maybe carbon rich
As it reaches sun, ice vapourises
Comet surface emit jets of vapourised material in sunlight - 106What is the coma of a cometDense gas & dust cloud surrounding comet
Hides nucleus
10,000,00 - 10,000,000km in diameter
Gases flow - fuzzy ball appearance - 107What is the hydrogen cloudHuge sphere (10^7km diameter)
Surrounding coma and nucleus
Hydrogen seen in UV not visible wavelengths and comes from UV dissociated water molecules - 108What is the dust tail in a cometFine dust particles freed from evaporating nucleus
~0.1-1 micrometer in diameter
Curved smooth shape
Combo of solar photons 'radiation pressure' and gravity - points away from the sun
Faint yellowish appearance - 109What forms a meteor showerAs a comets nucleus evaporates it leaves behind a trail of dust and rock fragments in the same orbit, it earth passes through this orbit it's called a meteor shower
- 110What is a meteor/oid/iteThe brief flash of light visible where a meteoroid enters the surface
If it survives and reaches the ground it's called a meteorite - 111What are the three categories of meteoritesStony - 95%
Iron - 4%
Stony iron 1% - 112What are the characteristics of stony meteoritesLook like ordinary rocks
Possible fusion crust
Difficult to find if weathered - 113What are the characteristics of a stony iron meteoriteEqual amounts of iron and silicates
- 114What are the characteristics of iron meteoritesContain 10-20% nickel
Prior to 2000BC main source of refined iron
Large nickel iron crystals; only possible if the material cooled slowly - 115What are the characteristics of large asteroidsMolten interior with thin crust similar to terrestrial planets
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- Tertiary Astronomy FlashCards sobre Astronomy Test #3, criado por Olivia Gniadek em 20-10-2018.
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