extra info (comets, asteroids, etc) Flashcards
(86 cards)
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.
2
Q
comet general info (tail)
A
- ice begins to melt from sun
- creates comet’s tail
- stretches due to solar wind
3
Q
Origins
A
- orbits easily affected
- were scattered into a wide variety of orbits.
- very large orbits could escape the sun
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.
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.
6
Q
Structure of comet
A
- cometary nucleus
- ice and gas with some dust
7
Q
Coma
A
- as the nucleus sublimates the comet forms a weakly help “atmosphere”
8
Q
Ion tail
A
- ions swept directly from the sun by the solar wind
- straight and relatively narrow
9
Q
dust (gas) tail
A
- solid denser particles driven off the coma
- wide and diffuse
- usually curved
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
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
12
Q
comet exploration
A
- Philae lander first to land on nucleus of a comet
- failed because it landed in crevasse.
13
Q
Ceres
A
- in the asteroid belt and considered the largest asteroid
- 933 Km in diameter contains 25% mass of all asteroids
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
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.
16
Q
Asteroid Belt
A
- located mars and jupiter
17
Q
C-type
A
- more than 75% of the asteroids
- extremely dark, C-rich
18
Q
S-type
A
- 17%
- relatively bright
- “stoney” – metallic nickel-iron with iron and magnesium silicates.
19
Q
M-type
A
- most of the rest
- bright
- pure nickel iron
20
Q
Ceres (unique)
A
- only object that has been rounded by its only gravity
- differentiated interior
- evidence of cryovolcanism
21
Q
Near earth asteroids
A
- ones that closely approach or cords the earth’s orbit.
- most less than 1 km
22
Q
meteorites
A
- fragments from asteroid belt
- very rare
- iron meteorites –> M - type
- stony-irons –> S-type
23
Q
meteoroids
A
- rocky / metallic bodies with Earth-crossing orbits
24
Q
Hoba
A
- largest meteorite in Namibia
25
difference between meteors, meteoroids, meteorite
- meteors "shooting stars"
- meteoroids glow as they heat up through earth's atmosphere
- meteorite : meteoroid found on earth's surface
26
shooting stars
- meteroid surface starts to melt on entry to atmosphere
- this is when they glow
-find dark crusts, melt pits, streaks of melt, aerodynamic molding
27
stars
- have a life cycle
- low mass or high mass
28
stellar nursery
- massive cloud of gas and fust permits the formation of new stars
- formation of larger stars can prohibit development of more low mass stars.
29
what has the life cycle of our sun been like and what is it going to be?
1. starfueling nebula
2. turn into a red giant or turn into a white, red, or blue dwarf.
30
classification of stars
- what they look like
- blue stars are HOTTER
- red stars are COLDER
31
what is the absolute magnitude of a star?
- it is how bright the star would be if it was 10 parsecs away from earth.
32
the sun
- classified as a G2 V star
- 99.8 % of the mass of solar system
- Hydrogen 75% of mass
- helium 24%
33
the suns power
- nuclear fusion of hydrogen in core
- can only happen at high temps and pressures
34
what is plasma?
- is no longer a gas and becomes plasma
- high energy
- electrons can move freely
35
sun rotation
- counterclockwise (POV north pole)
- 25 days at equator
- 36 days at poles
36
sun axial tilt
- 7 degrees from the ecliptic
37
sun interior (energy mechanisms)
- conduction : directing heat directly into
- radiation : radiating heat outward in air
- convection : replacing cold material with hot
38
what is the convection zone?
- zone of active circulation of gasses and convective heat transfer.
39
granulation
- convection zone surface mottled by a pattern of bright cells.
40
sun atmosphere
- photosphere is the visible yellow surface.
- chromosphere is a thick layer of very thin gas
41
what is a sunspot?
- dark spots on the photosphere with high magnetic field.
- dark bc they are cooler than surrounding areas.
42
umbra
- darkest region
- magentic field vertically aligned
43
penumbra
- light region around the outside
- magnetic field sits at a variable inclination to the umbra.
44
what is the suns corona and how hot is it?
- outermost part of the atmosphere
- composed of very low density ionized gases
- glow only visible during total eclipses
45
sun solar wind
- composed of mostly ionized gases
- disturbs earth
46
sun prominences
- protrusions of ionized gases from the chromosphere
- commonly looped controlled by magnetic fields
-
47
sun solar flares
- chromoshpere eruptions (not looped) of ionized gasses.
- rises rapidly (mins) and falls (hours)
- very bad for earth
48
what are coronal mass ejections and how are they different from solar flares?
- solar flares shoot out a lot of energy and gas
- coronal mass ejections -- the release of plasma
- often followe solar flares.
49
geomagentic storms
- combination of solar flares and CME's
50
stony meteorites
- chondrites and achondrites
- chondrites contain structures called chondrules
- rounded droplets of melted rock
51
What three things must be taken into consideration when developing a theory of planetary system formation?
- the composition
- the size
- the position relative to star of all extrasolar planets.
52
Immaneul Kant
- proposed planets form from a spinning (rotating disk).
53
Laplace
- first to describer in the mathmatical details of how planers form from rotating cloud of dust, ice and gas.
54
giant molecular clouds
- numerous regions of gas and dust dispersed among our galaxy.
55
Protoplanetary disks
- proplyds
- form around stars surrounding dust ice and gas
56
orion nebula
- millions of new stars forming in this cloud now
57
what are the first few stages of star formation that initiate nuclear fusion?
- motion of collaspe and collision (KE) is converted to heat
- temperature rises to tens of millions of degrees
- i give up
58
where does different material migrater to in the proto planetary disk?
- high melting point materials condense in inner disk and low melting point in materials in outer nebula.
- silicates / metal = inner
- ices / gases = outer
59
what effects do the stellar jets cause on the formation of planets?
- force most dust and gas outwards
- gas giants formed at this time
- caused comet's, kuiper belt, and Oort cloud objects
60
planetesimals
- small planets that begin to grow by accretion (impacts) with in disk.
61
transiting technique
- how 74% are found (exoplanets)
- dip in the stars output at regular intervals
- others can be found examining changes in gravity 7
62
Mu Arae C
- 2004 found the first rocky earth like planet
- not in habitable zone
63
what is the habitable zone?
- area around a star where liquid water could appear on surface
- size of planet important (internal heat).
64
radial velocity method
- 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
what is microlensing?
- 2.1% of discoveries
- light from a star is bent and focused by passing planet.
66
direct imaging
- 1.3%
- large planets such as these are emitting more IR radiation allowing them to be seen
67
distance from star
- most are very close, alot closer than our solar system
68
orbit period
- few days bc they are all so close
69
orbit eccentricity
- most so far found have rather extreme eccentricities
70
size and mass
- majority are neptune sized or several times bigger than jupiter
- 31% of all exoplanets around earth to mercury size
71
atmospheres
- light from stars passes through atmosphere
- can see the spectra from these stars
72
extremely large telescope
- visivle / near infrared telescope
73
exobiology
- the looking for life on planets (previously called)
74
astrobiology
- is the science of life on other planets is called astrobiology
75
water and energy source used to . . .?
build polymers that can store "information"
76
stromatolites
- are bacterial mounds that are found fossilized from earth's early history
77
panspermia
- seeds of life everywhere
- biomolecules brought to earth of comets, asteroids, and meteors.
78
archaea
- domain of single-cell organisms
- no nucleus
79
halophiles
- thrive on saline environments.
80
xerophiles (dry adapted)
- no known organism can survive without any water
81
desert varnish
- a thin coating (patina) of manganese, iron and clays on the surface of sun-baked boulders.
82
thermophiles and hyperthermophiles
- hyperthermophiles thrive in boiling or near - boiling water.
83
psychrophiles
- snow algae
- thrive at temps around 0 celsius
84
barophiles
- survive extreme pressure at bottom of Marianas trench.
85
acidophiles and alkaophiles
- acid hot and cold springs
86
endoliths and deep hot biosphere
- many dry and cold environments
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