Final Flashcards
The study of the moon is called
Selenologists
Most places on earth experience ____ high ___ and ___ low ___
two high tides & two low tides
Tides are created mainly by the influence of this celestial object:
moon
The ___ also causes earth’s tides, but it only has about ___ the effect of the moon.
sun; 1/2
When the moon is full or new, we experience ___ tides.
Spring
When the moon is at quadrature (1st or 3rd Quarters), we experience ___ tides
Neap
___ tides are the most exaggerated tides (really high high tides and really low low tides)
Spring
We have ___ tides and ___ tides each month
Spring; Neap
Explorer 1 discovered these belts of trapped, electromagnetically-charged particles:
Van Allen Belts
The moon’s crust, like other terrestrial bodies, is made of these two rocks:
granite & basalt
3 principal layers of a terrestrial planet or moon:
crust, mantle & core
The Earth’s core is principally made of these metals:
magnesium & iron
The arrangement of materials from densest at the core to least dense outward, is caused by this process:
chemical differentiation
Lunar maria are made principally of this rock type:
dark basalt
How is lunar far side different from its nearside?
Twice as thick crust
Why is the lunar far side different from its nearside?
Long axis aligned with Earth’s gravitational pull
This process is responsible for the movement of Earth’s surface features:
plate techtonics
The margins of tectonic plates are places where these occur:
earthquakes & volcanoes
Over 200 million years ago, this “supercontinent” existed:
Pangea
This plate boundary, such as in the mid-Atlantic Ocean, is where new crust is being made:
Divergent (Iceland)
This plate boundary, such as at Indian and Nepal, is where continental crust collides:
Convergent (Himalayas)
This plate boundary, such as at San Andreas, is where two plates run past each other:
strike-slip
Geologically speaking, the moon is:
dead
Scientific name for lunar soil:
regolith
If the moon has no volcanic activity or moonquakes or atmosphere, where does the regolith come from?
micrometeriorites from Earth’s atmosphere
All of the planets revolve in this direction:
counterclockwise
A planet’s rotational speed is directly related to its distance from the sun: T/F
False
The order of the planets outward from the sun:
rocky inner, gas giants outer
What are the two classes of planets?
Jovians (gas giants) & Terrestrials (rocky planets)
Terrestrials are found in the ___ solar system
inner
Jovians are found in the ____ solar system
outer
Largest planet in the solar system:
Jupiter
2nd largest planet in the solar system:
Saturn
The jovian planet’s main constituents:
hydrogen, helium, methane, ammonia
Largest terrestrial planet:
Earth
2nd largest terrestrial planet:
Venus
3rd largest terrestrial planet:
Mercury
Liquid water is found only on this planet:
Earth
The number of sunspots in the solar photosphere reaches a peak every ___ years
11
The suns’s visible surface:
photosphere
Large dark spots in the suns photosphere:
sunspots
Sunspots are dark because they’re ___ than the surrounding solar photosphere.
cooler
Photosphere temperature:
11,000 degrees
Sunspot parts - cooler, inner ___; slightly warmer, out ___
umbrea; penumbra
Sunspots are permanent features: T/F
false
Great glowing jets or clouds of gas int he solar chromosphere:
prominences
Outermost layer of the sun containing superheated plasma:
chromosphere
Large, powerful sunspots can often release these vast explosion eruptions:
flares
Subatomic particles ride the ___, creating ___ in Earth’s atmosphere
solar wind; aurora
Three early ideas of how the sun made energy:
chemical burning; gravitational contraction; bombardment by asteroids
___ devised the absolute magnitude scale, where 0 degrees - the point where all molecular activity stops
Williams Thompson (Lord Kelvin)
“Heat flows from a hotter body to a colder one” is the ___ of thermodynamics.
2nd
Besides the Kelvin scale, what are two other commonly used temperature scales:
fahrenheit & celsius
Convert to Fahrenheit: 0 degrees Celsius
32 degrees (freezes)
Convert to Fahrenheit: 100 degrees Celsius
212 degrees (boils)
Convert to Fahrenheit: 0 degrees Kelvin
-459 (molecular activity presumably stops)
Why weren’t geologists okay with Kelvin’s 30 million year estimate for the sun’s age?
Earth was estimated to several hundred million years old
___ devised the laws of special and general relativity.
Albert Einstein
This formula explains how matter is converted into energy, is the secret of the sun’s success:
E=MC2
In E=MC2, E = ___
energy produced
In E=MC2, M = ___
mass detroyed
In E=MC2, C = ___
speed of light
Temperature of the solar core:
27 million degrees
In the solar core, hydrogen is converted into ___
helium plus energy
The process fo splitting heavy elements into smaller units is nuclear ___
fusion
The combining of light elements into heavier ones is nuclear ___
fission
The sun’s nuclear fusion process, whereby hydrogen atoms combine to ultimately form helium and energy is called the ___
proton-proton chain
In more massive stars, the nuclear fusion process is called the ___
carbon cycle
The sun’s gravity field is so powerful that it can ___ light
bend
In 1919, during a ___, the deflection of starlight by the sun’s gravity field was first detected by Sir Arthur Eddington
total solar eclipse
These “wrinkle” in the Mercurian crust are the result of shrinkage of the planet:
lobate scarps
Impact feature on Mercury, over a thousand miles across:
caloris basin
This spacecraft once orbited Mercury, but it recently smashed into it:
Mercury Messenger
Compared to its crust and mantle, Mercury’s metal core is comparatively:
large
The atmosphere of Mercury is ___
non-existent
Venus’ atmosphere is made of:
carbon dioxide
Our sister planet:
Venus
The air pressure eon Venus is ___ that of Earth’s
90 times
The surface temperature on Venus:
900 degrees Fahrenheit
This effect has caused Venus’ atmosphere to become superheated:
greenhouse effect
With coronae and volcanoes and tectonics, geologically speaking, Venus is ___
active
Impact craters on Venus are not generally very big or very small, but mostly ___
mid-size
Mars is ___ the size of Earth
1/3-1/2
Mars rotation rate compared to Earth’s:
24 1/2 (slightly longer)
Mars has these cold polar features that grow and shrink with the seasons:
ice caps
Mars ice caps are made up of both water ice and ___
dry ice
In 1887, a ___ brought us within 35 million miles of ___
perihelic opposition; Mars
At the U.S. Naval Observatory, ___ found Mars’ two small moons.
large 26” refractor
Mars two small moons:
Phobos; Deimos
___ observed canali (channels) on Mars; the wod was mistranslated as ___.
Giovanni Schiaparelli; canals
He advanced the idea of intelligent Martians who built irrigation canals:
Percival Lowel
15 mile high volcano on Mars:
Olympus Mons
3000 mile long crack in the ground on Mars:
Valles Marineris
Dry river valleys, flood zones, alluvial fans and sea or lakebed, as well as hematite “blueberries” on the Meridian plains are a good indicator of ___ in the past on Mars.
liquid water
Gaspra, Ida, Mathilde and Eros are all examples of these:
Asteroids
Another name for an asteroid:
minor asteroids
He found the first asteroid telescopically, and named it Ceres:
Father Guiseppi Piazzi
___ Law is a numerical sequence which suggested the existence of the ___ as well as planets beyond the orbit of Uranus
Bode’s; asteroids
Bode’s Law is not a law because its is not ___ and it doesn’t always ___
universal; work
A popular scientific theory suggests that the dinosaurs were killed off by ___
meteors
A streak of light in the night sky is called a ___
meteroid
The rock in outer space prior to its burning up in the Earths atmosphere is called a ___
meteor
When a meteor hits Earth, it’s call a ___
meteorite
A bright meteor is known as a ___
fireball
If a meteor loudly explodes, it’s called a ___
bolide
Characteristics of meteorites:
heavy, magnetic, with fusion crust
This type of meteorite is metallic and readily identifiable as meteoritic in nature:
iron-nickel
Iron meteorites, cut, polished and etched, reveal these iron crystals:
widmanstatten pattern
These meteorites are made of stony materials, like earth rocks:
achondrites
These stony meteorites contain rounded bits of glassy rock:
chondrites
This meteorite type is a mixture of stony and iron
tektites
Jupiter is 1/2 billion miles from the sun, Saturn is 1 billion miles from the sun, Uranus is ___ billions miles from the sun
2
Because of its fast rotation and resulting centrifugal force, the planet Jupiter is wider at the equator than from pole to pole, making it ___
oblate
Large hurricane on Jupiter, 2-3x the size of Earth, w/ 400 mph winds:
Great Red Spot (GRS)
The GRS has been observed telescopically for ___ years
400
These atmospheric phenomena are to be found at Jupiter:
storms, lighting, and aurorae
This comet smashed into Jupiter in 1994:
Shoemaker-Levy 9
Jupiter’s outer moon - ancient, heavily cratered terrain:
Callisto
Largest moon in solar system (Jupiter) featuring ice, grooved terrain:
Garymede
Fresh, smooth-surface moon of Jupiter with fine cracks in icy crust and subsurface water:
Europa
Tidally heated, sulfur covered Jupiter moon with many active volcanoes:
Io
Which of the gas giant planets has rings:
Jupiter, Saturn, Neptune, Uranus
Volume of space controlled by a planet’s magnetic field:
magnetosphere
What are Saturn’s rings mainly made of:
tiny water ice chunks
Saturn’s density is less than:
water
Besides the ___ gap, there is also ___ division in Saturn’s rings
cassini; enke
Electrostatically charged dust suspended above Saturn’s rings:
spokes
Titan possess a thick atmosphere made principally of this gas:
nitrogen
This musician discovered the planet Uranus (almost named, “George”) in 1781:
William Herschel
What may have caused Uranus’ sideways tilt?
Collision, or planets may tip time to time
Of Uranus’ dozens of moons, this one has ice cliffs several miles high:
Miranda
This Earth-sized Neptunian feature has recently disappeared:
The great dark spot
This Neptunian moon orbits backwards or retrograde
Triton
These eruptive features are found on Triton:
Cryovolcanoes
Besides promoting Martian canals, Lowell postulated a ninth planet known at the time as ___
Planet X
Planet X was discovered in 1930 by ___
Clyde Tombaugh
Tombaugh discovered the planet one night while looking through a telescope: T/F
False
Planet X was soon named:
Pluto
Because Pluto’s orbit is more elliptical and offset from the others, it sometimes slips inside ___ orbit.
Neptunes
Besides Charon, Pluto has four more moons discovered only recently;
Nix, Hydra, Styx and Kerberos
The amount of reflectivity of a planet:
albedo
Kuiper belt objects such as Quaor, Sedna and Eris are classified as ___
ice dwarfs
Short-period comets may come from this belt outside Neptune’s orbit:
Kuiper belt
This spherical cloud of comets surrounds our solar system:
Oort Cloud
In 1682 he saw the comet that would later be named for him:
Edmund Halley
Haley thought that the comets did not travel in straight lines, but instead had ___
elliptical orbits
The orbits of many comets are highly ___
elliptical
Recent apparitions of Halley’s Comet:
1682, 1759, 1835, 1920 (142 years)
Halley’s Comet reappears in:
2052
Comet Hale-Bopp is a good example of a ___ period comet
long
Halley’s comet is a ___ period comet
short
Comet tails always point ___ from the sun due to the pressure of solar radiation and flow of subatomic particles outward - the solar wind.
away
Parts of a comet: the atmospheric head, called a ___
Coma
Parts of a comet: the dust and gas blown off the coma by the solar wind:
tail
The ___ tail of a comet extends out in a straight line
iron or gas
The ___ tail curves away from a comet in an arc
dust
Spacecraft have flown past comet tails, struck comets, and brought back comet tail material to Earth: T/F
True
The dense worlds are found in the ___ solar system
inner
The gas giants are located in the ___ solar system
outer
This kind of material boils at fairly low temperatures:
volatile
This kind of material remains solid at high temperatures:
refractory
This hypothesis best explains the moon’s origin:
large impact theory
The ___ suggested that a passing star pulled material from the sun to form planets
planetismal theory
The ___ suggested that hot gas blew off the sun to form planets
tidal theory
The ___ suggested the sun was a binary, but the companion blew up making planets.
double star theory
The ___ was the basis for our modern ___; suggesting that the sun and planets formed from a cloud created by exploding stars
condensation theory; solar nebula
According to the solar nebula theory, the solar system began about ___ billion years ago
4.6
How was this age determined? (universe)
Radioactive dating of meteorites
Large planet-building objects that formed from the solar nebula:
planetesimals
Massive objects destined to become planets:
protoplanets
If the solar nebula theory is right, then planets should be very ___ in the Universe.
common
Visual evidence of solar nebulae has been found as protoplanetary discs, or ___ in the ___ and in the spectroscopic wobbles or nearby ___.
proplyds; Great Orion Nebula; Stars Spectra
The speed of light, symbolized by the letter C, is approximately 186,000 miles per second. Given that there are roughly 33 million seconds in a year (60 X 60 X 24 X 365.25), light can travel about ____in one year.
6 trillion miles
The speed light can travel in one year:
lightyear
A “parallax second of arc,” is called a ___
parsac
A parsec is equal to about ___ light years
3.26
Objects beyond our solar system, such as stars, nebulae, and galaxies:
deep sky objects / deep space objects
All of the stars we can see with the naked eye are part of the ___
Milky Way Galaxy
This French astronomer made a list of a hundred or so fuzzy objects that weren’t comets:
Charles Messier
When comets are far from the sun, they don’t have ___
tails
One way to determine if a fuzzy object is a comet is to see if it ___ against the background of stars.
moves
The first Messier object, M-1, is really the ___ nebula, the exploded remains of a star
crab
The Messier list objects comprise of ___ star clusters & ___ star clusters
nebula, open; globular
At 4.3 LY, the nearest star to us after the sun (so far as we know):
Alpha Centauri (Rigel)
of stars in the Alpha Centauri system
3
Common center of mass in the Alpha Centauri system:
barycenter
Of the three stars of Alpha Centrauri, this red dwarf is the closest to us:
Proxima
The most common kind of star:
red dwarf
The rarest kind of star:
blue giant
Stars are formed from the contraction and heating up of ___
nebulae
Our sun is sometimes designated as a ___
yellow dwarf
Barnard’s Star and Proxima Centauri are ___
red dwarfs
The stars we see in the sky at night are predominately the most common - red dwarfs: T/F
False - too faint to see
Betelgeuse, Aldebaran and Antares are very bright but also very ___
cool
Stars: ___ and ___ giants
red; blue
Stars:___ and ___ dwarfs
white; red
Stars: ___ stars and ___ holes
neutron; black
Massive stars that blow up:
supernovas
Blue giant characteristics:
massive, hot, bright (Rigel, Vega)
Red giant characteristics:
big, cool (Betelgeuse, Antares, Aldebaran)
White dwarf characteristics:
small, hot (Sirius B, Procyon B)
Neutron stars are also called ___
pulsars
Pulsar star characteristics:
small, very hot, dense, magnetic, rotate rapidly
There is a neutron star in this nebula:
crab
___ is a good example of a black hole, but it was not discovered until the 1960’s
Cygnus X-1
Two basic kinds of star cluster: ___ and ___
open; globular
Open star clusters are also called ___
galactic star clusters
Two examples of open star clusters: ___ and ___
Pleiades; Praesepe
___ star clusters are spherical in shape
Globular
Globular star clusters contain ___ of stars, and they are ___
millions; very, very old
Two examples of globular star clusters: ___ and ___
M13 Hercules, Omega Centauri
A large cloud in outer space: ___ and ___
nebula; nebulae
Nebulae are composed of ___ and ___ and are trillions of miles across.
gas; dust
A ___ is mainly dust with very little gas, like the nebulosity around the Pleiades
reflection nebula
A ___, aka a Barnard cloud or Bok globule, has no bright stars within to light it up
dark nebula
An ___ is the birthplace of new stars; the gas is lit up by the light of stars within.
emission nebula
Examples of emission nebulae:
Lagoon, Eagle, Trifid, Rosette, N. American
A ___ is the listed-off outer atmosphere of a dying star.
planetary nebula
Examples of planetary nebulae:
Hourglass, Eskimo, Ring, Dumbell, Catseye, Spirograph, Helix
A ___ nebula is not really a nebula, but a distant galaxy, like the ___ galaxy
spiral; Andromeda
A star’s ___ tells us its temperature
color
Cool stars are ___
red
Hot stars are ___
blue
Newton used a prism to split the sun’s light into its component colors, a ___ spectrum
rainbow
The colors of a rainbow spectrum, as noted by Newton
red, orange, yellow, green, blue, indigo, violet
The light that the human eye can see is called ___
visible light
The prism separates the colors of visible light by ___ its different wavelengths to various degrees
bending
A rainbow fringe around an image produced by a lens is called ___
chromatic aberration
A complete collection of colors caused by splitting light
continuous spectrum
Name the full spectrum of light from lowest to highest energy:
radio, infrared, visible, ultraviolet, x-ray, gamma ray
A device that allows us to see absorption lines in a spectrum of light:
spectroscope
Dark absorption or Fraunhofer lines make up this kind of spectrum:
absorption spectrum
An absorption spectrum is caused by ___ absorbing select wavelengths of light
cool gasses
Bunsen and Kirchoff discovered this kind of visible light spectrum:
emission (bright light)
An emission spectrum is made by causing a low-density ___ to glow and emit select wavelengths of light
nebula
Each element has its own spectral ___ allowing us to identify the compositions of stars.
signature
Modern spectral analysis is accomplished not with prisms but with ___
diffraction gradings
This effect causes blue shifts and red shifts in stars ___
doppler
A higher frequency of light represents a ___ shift
blue
A lower frequency of light represents a ___ shift
red
The star Spica has red-shifted spectral lines; six months later its lines are blue-shifter. What causes this?
Earth revolution carries us towards and then away
Kind of velocity exhibited by red or blue-shifted stars:
radial
The greater the Doppler shift , the ___ the radial velocity of the object
greater
Faint stars without Arabic names, greek or Roman letter designations, have ___
Flamsteed numbers
He was England’s first royal astronomer and built the Greenwich Observatory:
John Flamsteed
This Danish astronomer was first to determine the speed of light:
Ole Roemer
The small shift in a star’s position caused by viewing it from two different locations:
stellar parallax
Given D=1/p, calculate the distance to Alpha Centauri if its parallax is .75 arc second
Divide 1.00 by .75 = 1.33 pc
After parallax has been taken into account, stars that change their positions among the other stars over time display what’s called:
proper motion
Two stars that orbit each other are called ____
binary stars
A binary where the stars are far enough from each other that the telescope can let you see them visually is called a ___
visual binary
At first glance, they look like a binary star, but they’re not actually bound gravitationally:
optical double
It looks like one star, but its spectral lines periodically split and then re-merge, the split again:
spectroscopic binary
A binary system where two stars pass in front of each other:
eclipsing binary
This star in Perseus is an eclipsing binary system:
Algol
The ___ of eclipsing binaries allows us to measure their orbits and velocities, their diameters and their masses and sometimes their share and surface features.
light curve
When a cool star eclipses a hot star, the system’s brightness drops ___ than when a hot star eclipses a cool one
a lot more
___ devised the spectral classes of stars
Annie Cannon
Spectral classes of stars from hot to cool:
O, B, A, F, G, K, M
Make up a mnemonic to remember the order:
Oh boy, a fat gorilla kicked me
Each spectral class of star is further subdivided into ___ classes
10
The ___ law applies to the way light dims with distance.
inverse square
If Jupiter is 500 million miles from the sun and Uranus is 2 billion miles out, how much less light does Uranus get than Jupiter
1/16
If star A and star B are the same size and the same temperature, but star B is three times farther away that star A, how much dimmer does star B appear than star A
9 times
If star A and star B are the same distance away, but star B is much fainter than star A, then star B’s absolute magnitude is much less than star A’s.
True
If star A and star B are the same size and temperature, but star A appears 100 times brighter than star B, then star A must be ___
10 times closer
The true measurement of a star’s visual brightness:
absolute magnitude
___ and ___ devised the Hertzsprung-Russel diagram
Hertzrung; Russell
The HR diagram plots a star’s ___ or ___ against its ___ or ___
temperature, spectral class; absolute magnitude, luminosity
The ___ of a star compares its brightness to that of the suns
luminosity
The absolute magnitude of a star is its apparent magnitude if it were ___ away from us.
10pc
At a distance of 10 pc, the sun’s apparent magnitude would be ___
5th Mv
___ stars have a red color
M
___ stars are orange
K
___ stars are yellow
G
___ stars are blue / white
O&B
In the HR diagram, hot stars are on the ___ side
left
In the HR diagram, cool stars are on the ___ side
right
In the HR diagram, bright stars are at the ___
top
In the HR diagram, dim stars are at the ___
bottom
90% of all known stars fall along this line on the HR diagram:
main sequence line
As you go up the main HR sequence, the star temperatures and brightness ___
increase
Cool dim stars:
red dwarf
hot, bright stars:
blue giants
cool, bright stars:
red giants
hot, dim stars
white dwarfs
Red giants and white dwarfs are off the main sequence: T/F
True
Stars are formed out of emission-___
nebulae
When the hydrogen in the core of a star is used up, the star begins to ___
die
The less massive the star, the ___ it lives
longer
The more massive the star, the ___ its lifespan
shorter
___ have such long lives that some of them started glowing when the universe was young
Red dwarfs
Our own sun has shone for ___
5 billion years
Our own sun will shine for another ___
5 billion years
The only star that typically never becomes a red giant is a ___
red dwarf
When the sun finally dies, it will explode as a supernova, then collapse to become a black hole: T/F
False
When the sun’s nuclear furnace shuts down, it will first ___; then ___ will begin to “burn” in a shell surrounding the solar core. About this same time, ___ will begin to burn in the core, making ___. The sun will then ___ and become a ___ giant.
contract & heat up; hydrogen; carbon; helium; swell; red
When the outer atmosphere of the sun “lifts off” and expands out into space it will make a ___
planetary nebula
Eventually the sun will burn up its shell hydrogen and core helium and collapse to become a ___
white dwarf
When the sun becomes a white dwarf, it will be the size of ___
Earth
A long time after the sun becomes a white dwarf, it will cool to become a ___
black dwarf
___ are exploding stars
Supernova
The last nearby supernova seen occurred in ___ in the ___, 160,000 LY away
1987; large megellanic cloud
A simple ___ is a dying star, but it not an exploding star
nova
Novae are ___ found in ___
white dwarfs; binary systems
Novae pull gas from its companion down onto an ___
accretion disc
White dwarf stars can brighten again and again, often at regular intervals of time: T/F
True
If a white dwarf pulls enough material to increase its mass sufficiently, it can become a ___
supernova
Exploding white dwarf stars are ___ supernovae
Type 1
Solitary massive stars that explode are ___
Type 2
___ stars result from supernovae
Neutron
Neutron stars are about ___ across and spin ___
10 miles; fast
___ proposed mass limits for stars that would either become white dwarfs, neutron stars or black holes
Chandrasekhar
If a dying star has more than 2.4 times the mass of the sun, it will become a ___
black hole
At the center of the black hole is a tiny, super-dense point called a ___
singularity
An ___ surrounds the black hole
accretion disc
A black holes speed-of-light point of no return is the ___
event horizon
Although we can’t see black holes directly, we can detect their presence due to their ___
gravity fields
___ can leak out from around black holes
x-rays & radiation
The distance from the singularity to the event horizon is known as the ___
schwarzschild radius
Schwarzchild radius is equal to ___ solar mass.
3km
if a black hole has 10 times the sun’s mass, its Schwarzschild radius is ___
30km
Joylen =
Pulsar
rapidly rotating =
Pulsar
Hershcel’s star counts led him to conclude that th eMilky Way galaxy was shaped like a ___
great disc or millstone
According to the Law of ___, matter is fairly evenly distributed throughout the Universe
homogeniety
Herschel thought we were at the ___ of the galaxy
center
A dark region in the Milky Way that passes through the Summer Triangle is called the ___
great rift
William Parsons, the Earl of Rosse, built this, the largest telescope in the world; the ___
Irish Leviathon
The Leviathan was powerful enough to observe individual stars in ___
other galaxies
Parsons suggested, as with the Whirlpool Nebula, that spiral nebulae might well be other ___
galaxies
___ catalogued ___ and found a connection between their absolute magnitudes and their light curve periods
Henrietta Leavitt; cepheid variable stars
The greater a Cepheid variable’s absolute magnitude, the ___ time it takes to go through a cycle.
more
Using Cepheid variable stars, we can calculate their ___ even if no parallex is observable.
distances
Until the 1920’s, astronomers weren’t sure if ___ nebulae were part of our galaxy, or other galaxies beyond.
spiral
The Andromeda galaxy is about ___ light years, or ___ miles away
2.5 million; 15 million trillion
___ argued that the distribution of ___ star clusters was centered on the constellation ___; therefore, that was the center of the galaxy, not here.
Harlow Shapley; globular; Sagittarius
Shapley also thought the Milky Way was much ___ than most thought.
larger
____ argued that spiral nebulae were really distant ___
Heber Curtis; galaxies
Curtis cited this phenomenon, found in the spiral nebulae, to prove they were far away:
Novas
In 1924 Edwin Hubble cited his observation of a ___ in M31 to priove it was another galaxy
Cephid Variable
Three basic galaxy types:
spiral; ellipticals; irregulars
White spiral and elliptical galaxies can be ___ or ___, irregulars are invariably ___
small, large; much smaller
E0 elliptical galaxies are ___
round
E7 elliptical galaxies are ___
very elliptical
E3 elliptical galaxies are ___
in-between round and elliptical
Sa spiral galaxies have ___ cores and ___ wound arms
large; tight wound
Sc spiral galaxies have ___ cores and ___ arms
small; widely flung
Sb spiral galaxies are ___ Sa and Sc spiral galaxies
in-between
A variant of the spiral galaxy is the ___ spiral that has a bar-shaped nucleus
SBa
S0 spirals have a ___ shape but no discernible ___
lens/spiral; arms
Two small companion galaxies to the Milky Way are the Large and Small ___
Magellanic Clouds
While our galaxy is a spiral, the Megallanic Clouds are ___
irregular
Our sun is about ___ from the galaxy’s center; we’re in the ___ arm
2/3rds out; Orion
At the center of the galaxy is a ___. Surrounding it is a flattened ___; surrounding the bulge and the disc is the ___.
Nuclear bulge; disc; halo
The disc of a galaxy usually contains 2 or 4 ___
arms
The nuclear bulge and the halo are often referred to as the __
spherical component
The ___ is gas and dust along the band of the Milky Way that keeps us from receiving visible light from the other side of the galaxy, and beyond our line-of-sight with the disc.
zone of avoidance
The sun takes ___ million years to make one orbit of the galaxy; this is a ___ year
240; galactic
___ is a region at the center of the Milky Way, where superheated gas swirls about at fantastic speeds, driven on by a ___ with ___ million times the mass of the sun!
Sagittarius; galactic black hole; 4
Stars that orbit rapidly in a ___ fashion are being sped up by ___ matter in the galactic ___, which surrounds the disc and hao
non-kepleriana; dark; corona
Our galaxy may not be a classic spiral shape, but instead a ___
barred spiral (SBa)
Stars once formed in the Milky Way’s ___ component, now it’s mainly in the ___’s spiral arms
disc
There are two basic star types: ___ stars are found mainly in the disc; ___ stars are found mainly n the spherical component.
Type 1; Type 2
Type 1 stars have fairly ___ orbits confined to the plant of the disk
tight
___ stars weave in and out of the disc, often traveling at right angles to the disc stars
Type 2
Type 1 stars contain lots of ___ elements
heavy
Type II stars are ___
metal-poor
Type 1 stars are relatively ___
young
Type II stars are relatively ___
old
The atoms in our bodies came from:
cores of stars exploded!
Local group stars are ___
cluster of galaxies to which the Milky Way belongs
Milky Way diameter:
100,000 ly
Discovering of Andromeda Nebula was by ___
Hubble
Stars with lowest average metal content found in what part of galaxy?
Halo and Nuclear Bridge
Shapley thought the sun is located where?
Disc of galaxy (1/2 way out)
Spiral arms are found in their part of the galaxy;
disc
___ is detected via its gravitational exertions on other ___
Dark Matter; galaxies
Many large galaxies have ___ at their cores
black holes
Number of stars in the Milky Way:
100-200 Billion
M31 galaxy has ___ stars and is ___ than the Milky Way
over 300 billion; larger
1000 pc’s is a kilo parsec, abbreviate as:
kpc
1,000,000 pc’s is a megaparsec, abbreviated as:
mpc
The ___ consists of over two dozen nearby galaxies; its two largest members are the ___ galaxy and the ___
Local group; Andromeda; Milky Way
Most of the galaxies are this type:
elliptical
The Local group is a ___ galaxy cluster; Virgo, Fornax, Hercules and Coma are all ___ clusters
poor; rich
Superclusters of galaxies seem to be arranged in a ___ type pattern, with large ___ within them. One of the largest structures seen is the ___
soap bubble; voids; great wall
Galactic collisions hardly ever happen Star collisions happen frequently; T/F
False
The ___ (satellite galaxies of the Milky Way) have collided with us before and will eventually be absorbed by our galaxy in an act of ___
Megallanic Clouds; galactic cannibalism
As a result of galactic collisions and cannibalism, another class of galaxies is the ____
Active or Pecular
___ are active elliptical galaxies
Radio Galaxies
___ are active spiral galaxies
Seyfert
The most distant active galaxies are called ___. They are about the size of our ___
quasars; solar systemm
Local group diameter?
1 mpc
Quasars are probably the ___ of active galaxies. They are most likely powered by ___ and they are the ___ things in existence.
core; black holes; oldest
Quasars have very large ___ shifts
red
___ can produce distorted or multiple images of more distant objects. And Einstein ___ is actually one quasar whose light has been split into four images that surround the intervening galaxy.
Gravitational lenses; cross
___ is the branch of Astronomy that’s concerned with the big questions, such as how did it all begin, where are we going, what will the Universe be like in the future.
Cosmology
___ pardon asks, “Why is the sky dark at night?”
Olbers
Thick obscuring dark clouds blocking starlight won’t explain why the sky is dark because…
eventually the clouds would light up and glow brightly
The five assumptions in Olber’s Paradox:
1: The universe is homogenous
2: Isotropic
3: Eternal
4: Infinite
5: Static
The fairly even distribution of stars through space is an example of the law of ___
homogeneity
The Universe is ___; it looks about the same no matter where you are
Isotropic
Which Olber’s assumptions are wrong?
Universe is probably not eternal, not static
How is the universe not static?
It’s expanding
If the universe is expanding, then it was once ___. ___ billion years ago, it would have all been in one place.
small; 14
He and Edwin Hubble convenience Einstein that the Universe was expanding; ___
LeMaitre
Hubble used the ___ of distant galaxies to infer that they were moving ___ from us, and that they universe was ___, which led to the ___ theory
red shifts; away; expanding; Big Bang
Using Hubble’s Law, (D=Vr/H), and a value of H=75 km/Mpc, if a galaxy has an observed recessional velocity of 150,000 km/sec, then its distance is ___
2,000 Mpc
He dislike the Big Bang theory and came up with his Steady State theory instead:
Fred Hoyle
___% of the universe is apparently made up of ___ matter. Of the matter we can see, the composition is about ___% hydrogen and ___% helium
90-95; dark; 75; 25
There is no definable ___ to the Universe, therefore there is no ___ to the Universe
edge, center
The universe is ___ as galaxies move ___ and ___ is created
expanding; outward; new space
The cosmic ___ is fairly homogeneous, isotropic, and very cold
background radiation
Quasars move at ___% the speed of light
90
The farther out in space we look, the farther back in time we look - this is the phenomena of ___
look-back time
There are quasars nearby that formed recently: T/F
False
Galactic collisions were more frequent long ago, as the Universe was a smaller place: T/F
True
The ___ theory, no longer popular, suggests that there was no beginning and there will be no end to the Universe.
Steady State
The ___ theory says that everything was created out of a singularity, which expanded outward, carrying all of us with it. Evidence that supports this theory is the observed ___
Big Bang; Expansion
The ___ may happen in the distant future if there is enough mass in the Universe to halt the expansion and bring everything back together again - in this case, the Universe is said to be ___. In the ___ theory, another Big Bang would then occur.
Big Crunch; closed; oscillating
If the universe is ___ or ___, then it will not collapse back in on itself; If it is open, it will ___ forever. f it is ___ is will slow to a stop but no contract
open, flat; open; flat
Predicted residual heat cosmic background radiation:
George Gamov
