AST Flashcards

Terms Definitions
wavelength (lambda)
speed/frequency (nu)
sulfuric acid
clouds on Venus
The Hertzsprung-Russell (H-R) diagram plots a star's temperature and its:
speed with direction (miles/hour North), vector quantity
Scientific Theory
Explanatory, predictive, always open to modification
waning gibbous
phase six of the moon
William Herschel discovered the green disk of ________ as the first telescopic planet.
joules and btu's
energy is measured in.....
Approximately how many cycles of tides are there in the Penobscot River each day?
low-density universe
In a low-density universe, the universe will expand forever and the galaxies will continue to recede from each other. Eventually, the galaxies will be too far apart to be seen from each other and their fuel supplies will eventually be exhausted.
We can measure the temperatures of stars from a study of their:
Long Period, Short Period
two types of comets
Green light burns ____ than blue light
The oblateness of the Jovian disks refers to their ________ equatorial diameters, compared to the polar diameters.
The formation of solid or liquid particles from a cloud of gas.
Main Sequence
An area on the Hertzsprung-Russel diagram that runs from lower left to lower right and includes more then 90% of all stars.
Most meteorites are found in the continent of ___.
____________ is when a planet is spinning on its axis, with each latitude of its apparent surface going around at a slightly different speed. (Two or three word answer. CAREFUL of spelling. Use NO punctuation.)
differential rotation
Scientific Method
Make a hypothesis, test it, revise hypothesis, repeat.
Cas A
about 1680. not clearly seen. shows evidence for jets, and a dim compact object in the center. The events that show compact objects also seem to show evidence of "elongated" explosions or "jets"
Milky Way Galaxy
about 100,000 ly across, contains about 100 billion
Approximately how many times larger is the size of the Sun compared to the size of the Earth?
About 100x
occurs when a light source is moving quickly away from an observer
dark nebulae
can be penetrated only with longer wavelengths such as radio and infrared
Starburst Galaxies
galaxies undergoing a RAPID BURST of star formation
the total power output of an object, usually measured in watts or in units of solar luminosities (L(Sun) = 3.8 x 1026 watts)
Earth's magnetic field:
Reverses polarity every 10,000 years, is generated by currents in its liquid iron core, has a north and south pole like a bar magnet, and screens us from the energetic particles from the sun.
elliptical galaxy
Galaxies that appear rounded in shape, often longer in one direction, like a football. They have no disks and contain very little cool gas and dust compared to spiral galaxies, though they often contain very hot, ionized gas.
Who invented the 3 laws of motion
Isaac Newton.
heliocentric cosmology
Sun is at center, Earth orbits like any other planet, Inferior planet orbits are smaller
stellar parallax
What is the most accurate way to determine the distance to
a nearby star?
Which of these bodies is mostly likely to break up overtime
comet nuclei
lunar eclipse
occurs when the moon passes into the earth's shadow, must be in "full moon" phase
While Saturn is almost as large as Jupiter, its mass is only about ________ of Jupiter's.
one third
M.S. turnoff
The point on a cluster's H-R diagram where its stars turn off from the Main Sequence, the age of the cluster is equal to the main-sequence lifetime of stars at the main-sequence turnoff
___ is when a planet is directly between the Earth and Sun.
Inferior conjunction.
eclipsing binaries
a double star system in which stars periodically pass in front of each other as seen from earth
1. Hot Dark Matter:
Lighter Electron mass or less Particles that travel quickly through the galaxy. Smoothly distributed over larger scales.
What would an inhabitant of a distant galaxy see if she observed the spectrum of the Milky Way galaxy?
A red shift
Stony Iron Meteorites
a mixture of IRON and STONE. they appear to have formed with a mixture of molten IRON and ROCK
latitude in degrees
the angle of polaris above the horizon (32 degrees) is the same as your...
The chemical elements that form the basic molecules needed for life are found
commonly through the cosmos
The formation of the moon is best described by the:
giant impact theory.
giant star
a star whose diameter is roughly 10 to 100 times that of the sun
Galaxy Clusters can contain up to
1000's of galaxies, All gravitationally bound together.Mostly elliptical galaxies.Collisions between galaxies break up spirals and make elliptical galaxies.Larger scale: superclusters, or clusters of clusters, exist.
Kepler's Law 2
A planet moves along its orbit with a speed that changes in such a way that a line from the planet to the Sun sweeps out equal areas in equal intervals of time
The Cassini Division is a gap in Saturn's rings caused by
gravitational interaction with Mimas
Hydrogen to Helium Fusion
4 hydrogen protons fuse and produce 2 positrons and 2 protons with 2 neutrons.
kelper's 2nd law
a line joining a planet and the sun sweeps out at EQUAL AREAS IN EQUAL INTERVALS OF TIME
A Neutron Stars Average mass and size:
1.4 SM (solar masses)10-20km (Size)
According to the Solar Max video, what happened when the solar cycle stopped for 100 years?
Temperatures dropped by about 2°.
In general, what can be said about type O and B stars compared to type K and M stars
They are hotter and younger
10. For how long does the emission of gamma-rays last for long duration gamma-ray
(a) tens of seconds
Where will the sun set on the day of the winter solstice as seen from Orono?
South of due west
Which of the following is a correct statement about astronomy and astrology?
Astronomy is a science, astrology describes the influence of objects in the sky on people.
What is Kepler's second law?
As a planet moves around its orbit it sweeps out equal areas in equal times.
Occam's Razor states that a scientific theory should:
Have a minimum number of arbitrary assumptions.
Our Sun orbits the center of our galaxy once every ?
250 million years.Already gone around over 18 times.Contains about 500 billion solar masses of material.
Ch.20 Q#18: If the standard candles you are using are less luminous that you think they are, then the distances you determine from them will be too small. *explain if the statement is true or false and explain clearly*
True as if you look at the mathematical insight you will see that distance and luminosity are directly related. You can compare two base cases, let's say L= 4x10^23 then decrease it to L2=4x10^20 and filling it in the equation we can tell that L>L2, thus the decrease.
• showing the motion of a ball near Earth's surface, depicts how gravity
Causes the ball to accelerate downwards
Why does the cloud eventually form a disk shape?
The matter that is falling in horizontally is resisted by the spinning motion and this matter begins to spit and flatten
Which of the following is the best description of a galaxy?
A system of billions of stars orbiting a common center.
Why isn't there a huge planet in the Kuiper Belt?
Because Neptune got rid of some objects in the Kuiper Belt
9. What is the typical speed of the jet produced in gamma-ray bursts?
(b) Very close to the speed of light
total solar eclipse
SN 386
earliest on record
How many constellations are there?
Spacecraft to the Jovian planets
position north or south of equator
Which part of the electromagnetic spectrum generally gives us our best views of stars forming in dusty clouds?
Compared to the terrestrial planets, the Jovians have ________ average densities
Irregular Galaxy
Galaxy with no definite shape.
The vast majority of asteroids are most similar in shape to:
light year
9.5 trillion km (measure of distance)
Force ∝ mass1×mass2/ distance²
Law of universal gravitation
Io, Europa, Callisto, Ganymede
the four Jupiter's moons
circumpolar stars
are the stars that never set
Cometary dust tails lag behind the bluish ion tails as the comet rounds the Sun.
neutron degeneracy pressure
degeneracy pressure exerted by neutrons, as in neutron stars
Mars' diameter is about ___ the Earth's.
3. Halo-
Spherical shell that surrounds the disk. Contains the 
dark matter and globular clusters: large groups of stars (Pop II) that 
formed before the disk of our galaxy.
Filaments on the Sun are the same thing as what other feature?
LARGE DARK PLAINS on the lunar surface caused by large impacts that breached the lunar crust causing moltent lava to FLOW and HARDEN
Black Body (BB) Curves
Wavelength decreases as Temp. increases - the hotter the BB the more the peak shifts to the blue
What is thought to cause Io's volcanism?
Jupiter's gravity
Orbital Energy
sum of its kinetic energy and gravitational potential energies (always stays the same)
A recurrent nova could eventually build up to a
type 1 supernova
Brown dwarfs
Fragments of collapsing gas and dust that did not contain enough mass to initiate core nuclear fusion. Become cold fragment of unburned matter.
solar/stellar models
Model, solar system, was created from a mixture of hydrogen, helium, tiny amounts of heavier elements. These then compressed in on each other and formed the solar system.
Stellar parallax is:
A natural consequence of a heliocentric model and the apparent angular shift of nearby stars relative to further ones.
expanding universe
The idea that the space between galaxies or clusters of galaxies is growing with time.
The ____ is the apparent change in the position of an object due to a change in the location of the observer. Greek astronomers attempted to use what to measure the distance to the sun, moons, and planets, and stars.
The Sun Spot number cycle is how long?
11 years.
Red Giant
when hydrogen burns out in the center, excess heat flowing from the contracting core causes the outer layers to gain energy. They then expand and cool. The outside becomes larger, cooler, redder, and more luminous.
a part of the comet which is not visible, small porous rock containing ices of water, CO2, CO and NH4. Range in size from 10 to 100 Km
How old is the solar system?
4.6-5 billion years old
If the light from a galaxy fluctuates in brightness very rapidly, the region producing the radiation must be
very small
Spiral Galaxies
they contain a DISK and SPIRAL arms. spirals contain gas and dust and HOT BRIGHT stars
The ___ sphere is the concept of the bowl of the night that many ancient cultures believed.
Ordinary Gas Pressure
Increase in Temp => Increase in Pressure
Increase in Gas Speed => Increase in Pressure
Increase in Gas Density (more particles) => Increase in Pressure
Who built an observatory and was 10 to 20 times more accurate.
Tycho Brahe
What is the source of the outward forces that balances gravity in a Main Sequence star?
Thermonuclear (fusion) reactions
What type of object will a white dwarf eventually become?
black dwarf
What is the equatorial diameter of the Earth?
About 10,000 km
Which of these pairs of binaries would appear most similar in color telescopically
MIV and K9V
globular (star) cluster
A group of several thousand to a million stars that appear from earth to be close to each other and arranged in the shape of a ball.
kelper's 3rd law
the square of a planets orbital period is proportional to the cube of the length of its orbit's semimajor axis, P^2 = a^3, planets move faster when closer to the sun
Inverse square law
light weakens as it spreads out and travels.
Compared to a flat geometry, a positively-curved geometry (closed) has the property that
parallel, straight lines must meet.
The smallest high tide occur when the Moon phase is
first or third quarter
A logical sequence of galaxy evolution would be
quasar, active galaxy, normal galaxy
The wavelength of a wave is:
The distance between two adjacent peaks of the wave.
How figured out the half-life property of radioactive stuff? When?
Arthur Holmes; 1910 - 1921
What do pulsars appear to be?
rotating neutron stars immersed in hot gas
What is Newton's third law?
For any force, there is always an equal and opposite reaction force.
kepler's 1st law
orbit of a planet about the sun is an ELLIPSE with the sun at one focus
Which statement about the highlands on our Moon is correct?
They have far higher density of craters than the lowlands
Ch.19 Q#21: If I could see infrared light, the galactic center would look much more impressive. *explain if the statement is true or false and explain clearly*
True as interstellar medium obstructs most of our view of the observable universe
How hot is the core of the sun said to be?
13,600,000 degrees kelvin
The most likely ingridients of a typical comet's nucleus are:
Dust and rocky particles mixed with primarily water ice.
What is the Jovian problem?
Disks are only supposed to live for a few million years, but it seems that it would take longer for the Jovian planets to form
How long does it take for radiation, created in the core of the Sun, to reach Earth?
from hundreds of thousands to a million years
What is the shape of our galaxy?
Flattened with a central bulge, like a fried egg
Astronomers think that most new comets come from:
A spherical cloud of material in the outer part of the solar system.
Ch.22 Q#35: The major evidence for the idea that the expansion of the universe is accelerating comes from observations of (a) white dwarf supernovae (b) the orbital speeds of stars within galaxies (c) the evolution of quasars *explain your answer*
It's A as they are good standard candles to determine whether gravity is slowing down expansion but as you know it doesn't dark energy accelerates it
What can you conclude about a Type I supernova?
it was originally a low mass star
On a H-R diagram, a protostar would be
above and to the right of the main sequence
In measuring a galaxy's redshift, what do we do mathmatically?
Divide EXAMPLE: D = v/Ho 89,000 = 1236 Mpc 72
/ 129

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