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Planets > extra info (comets, asteroids, etc) > Flashcards

extra info (comets, asteroids, etc) Flashcards

1
Q

Oort cloud

A
  • spherical cloud of comets which lies around 50,000 AU away from the sun.
  • outer extent defines the gravitational boundary of our solar system.
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2
Q

comet general info (tail)

A
  • ice begins to melt from sun
  • creates comet’s tail
  • stretches due to solar wind
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3
Q

Origins

A
  • orbits easily affected
  • were scattered into a wide variety of orbits.
  • very large orbits could escape the sun
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4
Q

How can comets enter the inner solar system?

A
  • kuiper belt comets have their orbits disturbed by neptune and uranus
  • Oort clouds have theirs disturbed by passing stars.
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5
Q

Orbits of comets

A
  • take hundreds and millions of years to orbit sun (long period)
  • short period is around 200 years
  • highly eccentric orbits and at all inclinations of ecliptic.
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6
Q

Structure of comet

A
  • cometary nucleus
  • ice and gas with some dust
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7
Q

Coma

A
  • as the nucleus sublimates the comet forms a weakly help “atmosphere”
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8
Q

Ion tail

A
  • ions swept directly from the sun by the solar wind
  • straight and relatively narrow
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9
Q

dust (gas) tail

A
  • solid denser particles driven off the coma
  • wide and diffuse
  • usually curved
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10
Q

what are the tails made of, how do they form and how are they oriented?

A
  • made up of hydrogen, coming from water that is evaporated
  • also made of dust that got melted and set free
  • does not indicate direction of travel
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11
Q

Hailey’s comet

A
  • best know short period comet
  • next appear in 2061
  • very dark
  • albedo 0.03
  • one of darkest objects in the solar system
  • carbon rich
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12
Q

comet exploration

A
  • Philae lander first to land on nucleus of a comet
  • failed because it landed in crevasse.
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13
Q

Ceres

A
  • in the asteroid belt and considered the largest asteroid
  • 933 Km in diameter contains 25% mass of all asteroids
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14
Q

Asteroid

A
  • small airless, rocky bodies that orbit the sun
  • much smaller than planets
  • remnants left over from the formation of the solar system
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15
Q

what are some of the main characteristics of asteroids?

A
  • low eccentricates
  • variable albedos
  • highly cratered, old surfaces
  • asymmetric shapes
  • metallic and stony asteroids are found closer to the sun
  • mixed asteroids found further out.
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16
Q

Asteroid Belt

A
  • located mars and jupiter
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17
Q

C-type

A
  • more than 75% of the asteroids
  • extremely dark, C-rich
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18
Q

S-type

A
  • 17%
  • relatively bright
  • “stoney” – metallic nickel-iron with iron and magnesium silicates.
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19
Q

M-type

A
  • most of the rest
  • bright
  • pure nickel iron
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20
Q

Ceres (unique)

A
  • only object that has been rounded by its only gravity
  • differentiated interior
  • evidence of cryovolcanism
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21
Q

Near earth asteroids

A
  • ones that closely approach or cords the earth’s orbit.
  • most less than 1 km
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22
Q

meteorites

A
  • fragments from asteroid belt
  • very rare
  • iron meteorites –> M - type
  • stony-irons –> S-type
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23
Q

meteoroids

A
  • rocky / metallic bodies with Earth-crossing orbits
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24
Q

Hoba

A
  • largest meteorite in Namibia
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25
Q

difference between meteors, meteoroids, meteorite

A
  • meteors “shooting stars”
  • meteoroids glow as they heat up through earth’s atmosphere
  • meteorite : meteoroid found on earth’s surface
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26
Q

shooting stars

A
  • meteroid surface starts to melt on entry to atmosphere
  • this is when they glow
    -find dark crusts, melt pits, streaks of melt, aerodynamic molding
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27
Q

stars

A
  • have a life cycle
  • low mass or high mass
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28
Q

stellar nursery

A
  • massive cloud of gas and fust permits the formation of new stars
  • formation of larger stars can prohibit development of more low mass stars.
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29
Q

what has the life cycle of our sun been like and what is it going to be?

A
  1. starfueling nebula
  2. turn into a red giant or turn into a white, red, or blue dwarf.
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30
Q

classification of stars

A
  • what they look like
  • blue stars are HOTTER
  • red stars are COLDER
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31
Q

what is the absolute magnitude of a star?

A
  • it is how bright the star would be if it was 10 parsecs away from earth.
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32
Q

the sun

A
  • classified as a G2 V star
  • 99.8 % of the mass of solar system
  • Hydrogen 75% of mass
  • helium 24%
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33
Q

the suns power

A
  • nuclear fusion of hydrogen in core
  • can only happen at high temps and pressures
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34
Q

what is plasma?

A
  • is no longer a gas and becomes plasma
  • high energy
  • electrons can move freely
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35
Q

sun rotation

A
  • counterclockwise (POV north pole)
  • 25 days at equator
  • 36 days at poles
36
Q

sun axial tilt

A
  • 7 degrees from the ecliptic
37
Q

sun interior (energy mechanisms)

A
  • conduction : directing heat directly into
  • radiation : radiating heat outward in air
  • convection : replacing cold material with hot
38
Q

what is the convection zone?

A
  • zone of active circulation of gasses and convective heat transfer.
39
Q

granulation

A
  • convection zone surface mottled by a pattern of bright cells.
40
Q

sun atmosphere

A
  • photosphere is the visible yellow surface.
  • chromosphere is a thick layer of very thin gas
41
Q

what is a sunspot?

A
  • dark spots on the photosphere with high magnetic field.
  • dark bc they are cooler than surrounding areas.
42
Q

umbra

A
  • darkest region
  • magentic field vertically aligned
43
Q

penumbra

A
  • light region around the outside
  • magnetic field sits at a variable inclination to the umbra.
44
Q

what is the suns corona and how hot is it?

A
  • outermost part of the atmosphere
  • composed of very low density ionized gases
  • glow only visible during total eclipses
45
Q

sun solar wind

A
  • composed of mostly ionized gases
  • disturbs earth
46
Q

sun prominences

A
  • protrusions of ionized gases from the chromosphere
  • ## commonly looped controlled by magnetic fields
47
Q

sun solar flares

A
  • chromoshpere eruptions (not looped) of ionized gasses.
  • rises rapidly (mins) and falls (hours)
  • very bad for earth
48
Q

what are coronal mass ejections and how are they different from solar flares?

A
  • solar flares shoot out a lot of energy and gas
  • coronal mass ejections – the release of plasma
  • often followe solar flares.
49
Q

geomagentic storms

A
  • combination of solar flares and CME’s
50
Q

stony meteorites

A
  • chondrites and achondrites
  • chondrites contain structures called chondrules
  • rounded droplets of melted rock
51
Q

What three things must be taken into consideration when developing a theory of planetary system formation?

A
  • the composition
  • the size
  • the position relative to star of all extrasolar planets.
52
Q

Immaneul Kant

A
  • proposed planets form from a spinning (rotating disk).
53
Q

Laplace

A
  • first to describer in the mathmatical details of how planers form from rotating cloud of dust, ice and gas.
54
Q

giant molecular clouds

A
  • numerous regions of gas and dust dispersed among our galaxy.
55
Q

Protoplanetary disks

A
  • proplyds
  • form around stars surrounding dust ice and gas
56
Q

orion nebula

A
  • millions of new stars forming in this cloud now
57
Q

what are the first few stages of star formation that initiate nuclear fusion?

A
  • motion of collaspe and collision (KE) is converted to heat
  • temperature rises to tens of millions of degrees
  • i give up
58
Q

where does different material migrater to in the proto planetary disk?

A
  • high melting point materials condense in inner disk and low melting point in materials in outer nebula.
  • silicates / metal = inner
  • ices / gases = outer
59
Q

what effects do the stellar jets cause on the formation of planets?

A
  • force most dust and gas outwards
  • gas giants formed at this time
  • caused comet’s, kuiper belt, and Oort cloud objects
60
Q

planetesimals

A
  • small planets that begin to grow by accretion (impacts) with in disk.
61
Q

transiting technique

A
  • how 74% are found (exoplanets)
  • dip in the stars output at regular intervals
  • others can be found examining changes in gravity 7
62
Q

Mu Arae C

A
  • 2004 found the first rocky earth like planet
  • not in habitable zone
63
Q

what is the habitable zone?

A
  • area around a star where liquid water could appear on surface
  • size of planet important (internal heat).
64
Q

radial velocity method

A
  • measure small spectra of starlight induced by movement away and towards observer of star.
  • due to gravity of nearby planet
  • RED MOVING AWAY
  • BLUE MOVING TOWARDS
65
Q

what is microlensing?

A
  • 2.1% of discoveries
  • light from a star is bent and focused by passing planet.
66
Q

direct imaging

A
  • 1.3%
  • large planets such as these are emitting more IR radiation allowing them to be seen
67
Q

distance from star

A
  • most are very close, alot closer than our solar system
68
Q

orbit period

A
  • few days bc they are all so close
69
Q

orbit eccentricity

A
  • most so far found have rather extreme eccentricities
70
Q

size and mass

A
  • majority are neptune sized or several times bigger than jupiter
  • 31% of all exoplanets around earth to mercury size
71
Q

atmospheres

A
  • light from stars passes through atmosphere
  • can see the spectra from these stars
72
Q

extremely large telescope

A
  • visivle / near infrared telescope
73
Q

exobiology

A
  • the looking for life on planets (previously called)
74
Q

astrobiology

A
  • is the science of life on other planets is called astrobiology
75
Q

water and energy source used to . . .?

A

build polymers that can store “information”

76
Q

stromatolites

A
  • are bacterial mounds that are found fossilized from earth’s early history
77
Q

panspermia

A
  • seeds of life everywhere
  • biomolecules brought to earth of comets, asteroids, and meteors.
78
Q

archaea

A
  • domain of single-cell organisms
  • no nucleus
79
Q

halophiles

A
  • thrive on saline environments.
80
Q

xerophiles (dry adapted)

A
  • no known organism can survive without any water
81
Q

desert varnish

A
  • a thin coating (patina) of manganese, iron and clays on the surface of sun-baked boulders.
82
Q

thermophiles and hyperthermophiles

A
  • hyperthermophiles thrive in boiling or near - boiling water.
83
Q

psychrophiles

A
  • snow algae
  • thrive at temps around 0 celsius
84
Q

barophiles

A
  • survive extreme pressure at bottom of Marianas trench.
85
Q

acidophiles and alkaophiles

A
  • acid hot and cold springs
86
Q

endoliths and deep hot biosphere

A
  • ## many dry and cold environments

Planets (2 decks)

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