Astronomy definitions Flashcards

Terms Definitions
sun (greek)
Sun centered
The Earth's Satellite.
70% water on surface
90% of stars
main sequence
Smaller than Earth's Moon
an atmospheric phenomenon consisting of bands of light caused by charged solar particles following the earth's magnetic lines of force
A round, three-dimensional object whose surface is the same distance from its center at all points; Earth is a sphere that bulges somewhat at the equator and is slightly flattened at the poles
Gives off radiation & spins
Fuzzy border of a shadow.
HR Diagram plots...
Luminoscity vs. Temperature
slugs, kilograms
mass is measured in these
the center around which something rotates
German astronomer who first stated laws of planetary motion
small additional circles in ptolomey's geocentric model used to explain retrograde motion
movement of earth around its axis
having the earth as the center
discovered uranus, two moons of Saturn, and lots of double stars and nebulas
which planet has the most moons
- perfected the telescope
- Discovered Jupiter's moons, Venus' phases, sunspots, and lunar topography
- proved cosmos were imperfect
Radio Galaxy
Very bright, often giant, elliptical galaxy that emits as much or more energy in the form of radio wavelengths as it does wavelengths of visible light.
Dirty snowballs of ice mixed with dust, frozen carbon dioxide and organic matter
kirchhoff's laws
Three statements formulated by gustav kirchhoff describing what physical conditions produce each type of spectra
on terrestrial planets, layers of differing ______ preserved as surfaces ______ and solidified
densities, cooled
magnetic storms cooler by 2,000K on suns surface
the branch of physics that studies celestial bodies and the universe as a whole.
Ancient astronomers reffered to the planets as
wandering stars
the Earth travels or _________ around the sun once every 365 1/4 days
the middle layer of the sun's atmosphere
apparent change of position in closest stars when viewed 6 months apart
a bright, convective cell or current of gas in the Sun's photosphere; appear bright because they are hotter than the descending gas that seperates them
stars with high masses live longer than stars with lower masses
discovered a way to measure earth's radius
It holds Earth in orbit, affects Earth's tides and provides us with heat and light
what are the inferior planets?
mercury and venus
Celestial object
Any object outside or above Earth's atmosphere
differential rotation
the condition in which different parts of an object rotate at different speeds; one example would be a spiral galaxy whose inner regions rotate faster than its outer regions.
Nuclear fusion
a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy
many of the large moons have ______ intrinsic magnetic fields.
produce variations in the amount of sunlight incident on Earth include changes in the earth's rotational wobble, axial tilt, and orbit shape
Milankovich cycles
____% of the universe is composed of dark matter
daytime is shorter in SF than in SD
space shuttle
A reusable spacecraft designed to make many trips and that carries astronauts, satellites, and other cargo to and from space
the force of gravity acting on an objects
1 to 100 days, yardsticks to other galaxies
escape velocity
speed necessary for an object to completely escape the gravity of a large body such as a moon planet or star; depends on where you start from
celestial equator
intersection of a plane through the equator and the celestial sphere
This term describes the amount of time required for the moon to make a full cycle of phases.
Take 24 hours to revolve around Earth and always above same point on Earth's surface - most communication satellites are in this orbit
Jupiter, Saturn
Which planets have a rocky core, metallic hydrogen (currents here produce the magnetic field)
what is a protostar
a central concentration of matter
conservation of momentum
total momentum of interacting objects cannot change
the two days each year when the hours of light and darkness are equal
leap year
every four years add an extra day. Gregorian calendar: leap year if the year is divisible by 4, not if year is divisible by 100, IS if year is divisible by 400
RR Lyrae type stars
have shorter periods than cepheids, color is bluer
light years
light years What unit of distance is used to measure between stars?
Large Megallanic Cloud
Form of an irregular galaxy. Active star formation
the tendency of an object to resist a change in motion
The center of the sun where is sun's energy is produced
light year
the unit of length equal to the distance light travels through space in one year
Huge group of stars, gas and dust that travels together through space.
geocentric model of the universe
earth at center of universe
Proper Motion
The rate at which star change its position among the other stars in the sky
solar flare
an explosion of hydrogen gas from the sun's surface when loops in sunspot regions suddenly connect
lunar month
the Moon's synodic period, or the time between successive similar phases
Pieces of rock or or dust form an asteroid or comet
If nucleas has too many or too few neutrons, unstable to radioactive decay
apparent magnitude
the magnitude or brightness of a star as it appears to an observer on the earth
solar day
the period of time from which the sun is directly overhead until the next time the sun is directly overhead.
newton's law of gravitation
the strangth of force of gravity between two objects is determined by two factors: mass and distance
radiation zone on sun
runs from core to 71% transparent gas
earth's revolution
the amount of time it takes earth to revolve around the sun. which is a year/365 days.
white dwarf
a small hot dim star created by the remaining material that is left when a red giant dies
solar eclipse
when the moon moves in a line directly between earth and the sun, casting a shadow on earth
________ galaxies are patchy, sprawling, and young.
Irregular. These galaxies are those that are not easily classified into the other types.
Kepler's First law
All planets move about the sun in an elliptical orbit with the sun at one focus
Unique Feature of Uranus
Tilt of rotation axis is about 90 degrees (William Herschel discovered in 1700s)
Thermonuclear Fusion
This marks the birth of a star when it reaches 10 million Kelvin
if star a seems brighter than star b star a is probably
closer and bigger
What is standard time?
The mean solar time for a meridian of longitude at the center of the zone.
During a stars life only the small stars
go directly to white dwarf
Does the longest or shortest wavelength have the lowest energy?
-the longest wavelength has the lowest energy
What conditions are needed for there to be a dynamo in the core of the Earth, and what does this dynamo produce?
you need convection, liquid core, and rotation. it produces a shift in the axis
What are the stats of the Cosmic abundances?
The terrestrial elements correspond to the most abundant.
Peaks are at multiples of 4 mass units, such as C12, O16, Ne20, and Mg 24
One frequently asked question about Lorentz Contraction is: is it REAL? The TWO correct answers to that question are ...
Yes, in the sense that atoms, rulers, measuring devices all contract by the same proportion. So if an object was 15 ruler-lengths long it will always stay 15 ruler-lengths long. Yes, in the sense that any observer travelling at the same speed with respect to the object measured will measure the same contraction.
Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of ripples on the pond.
They have a frequency of 2 hertz.
All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new moon?
The orbital plane of the moon is tilted by about 5 degrees to the elliptic plane
it heats and ionizes the earth's upper atmosphere, producing the ionosphere and stratosphere
what does the sun's variable x-ray and ultraviolet radiation do to the earth's atmosphere?
why do scientists think there was once life on mars?
a piece of mar's surface was found in antarctica containing fossils
no atmosphere
positive particles (atom)
piece of equipment
pressure 1/150 of earths
super cluster
clustering of clusters
Stars shifts in positions
smooth, gray, areas... lunar seas
electrons and electrically charged particles(ions) which flow outward from the sun to the rest of the solar system
used to classify stars
H-R diagram
johannes kepler
hired assistant of brahe
Everything that exists in any place
protoplanets cleaning up materials in their orbits and becoming planets after 100 million years
the logarithmic measure of the brightness of an object
-Believed universe could be described using mathematics, founded geometry
-Believed everything was harmonious, Kosmos
-First to record earth as a sphere
-Censored irrational numbers
-Discovered 5 platonic solids
the number of complete wavelengths that pass a point in a given time. measured in Hertz.
everything in existence
what is the universe?
saturn density
700. winner of least dense!!
Four fundamental elements (500 BC)
o Earth, fire, air, water
 Didn't create this idea, just pushed it forward
 Viewed air as the most fundamental
 Air compressed itself, which turned into rain, and then earth
 Air expanded, ignited, and became a star (fire)
o Universe in order
Sally Ride
First American woman in space
the distance, measured in the direction of propagation of a wave, between two successive points in the wave that are characterized by the same phase of oscillation.
autumnal equinox
sun crosses the celestial equator southward
stars and hydrogen bomb work by
nuclear fusion
Stefan's law
Hotter objects emit more total radiation per unit surface area
cloud of interstellar gas and dust which collapses in on itself as a result of gravity and forms a star
north celestial pole
point directly over north pole
the process by which matter changes the direction of light
-the amount of energy the stars radiate per unit time in all directions
- can't classify by apparent brightness because it depends on its distance from us
- we can only directly measure brightness of stars so we have to measure distance to the star in order to calculate luminosity
distance modulus
the difference between the apparent and absolute magnitudes of an object
bend light with a curved mirror
reflecting telescope
low frequency small amplitude visible light would be
dim red
The formation of solid or liquid particles from a cloud of gas
4th planet- rusty surface with solid CO2 polar caps, permafrost water layer and previous life? has highest mountain and biggest valley in solar system
first element to fuse in any star
Lagrangian points
Points of gravitational stability in the orbital plane of a binary star system, planet, or moon. (p. 214)
a viscid, watery fluid, secreted into the mouth by the salivary glands, that functions in the tasting, chewing, and swallowing of food, moistens the mouth, and starts the digestion of starches.
chunks of rock found mainly in the region of space between Mars and Jupiter
axis tilt
tilted 23.5, reason why we have seasonal changes
This planet has an atmosphere 90 times as thick as Earths
Semi major axis
half the length of major axis
has three moons, one about half it's size
during an eclipse the place on Earth that sees a total eclipse
Lunar Eclipse
occurs when the moon enters Earth's shadow
solar system
sun, planets, and all the other objects that revolve around the sun
tycho brahe
made observations used by Kepler of planetary motion
Which of the following is a greenhouse
gas in the sense of absorbing infrared radiation?
water vapor
absolute magnitude
(astronomy) the magnitude that a star would have if it were viewed from a distance of 10 parsecs (32.62 light years) from the earth
Hubbles research
Showed that the recession speeds of most galaxies are related to the distances to the galaxies.
Remember: V=H -----Hubbles Law
The distance that light travels in one year, about 9.5 million million kilometers.
The transfer of heat by EM waves (photons, light)
reaches 10tothe7k
hydrogen ignites fusing helium at a furious rate, furious and violent, suddenly flares up in luminosity and then fades away as some of the fuel is exhausted and remainder blown off into space
population I
Stars rich in atoms heavier than helium. Nearly always relatively young stars found in the disk of the galaxy. (p. 264)
drake equation
a way to estimate the possibility of life in the universe
longest radio waves can be observed in any weather
radio astronomy
S-type asteroid
one of a class of asteroids whose reflectance spectra show an absorption feature due to the mineral olivine
summer solstice
The point on the ecliptic where the Sun is farthest north of the celestial equator; the day with the largest number of daylight hours in the northern hemisphere. around June 21.
cosmological conundrum (puzzle)
All observers, located anywhere in the universe, will observe all other galaxies to be moving away from them. This is because galaxies are separating from each other due to the EXPANSION OF SPACE BETWEEN THEM (raisin bread rising and balloon filling with air)
what is the radius of a white dwarf?
10^4 kilometers
The rise and fall of the ocean water caused mainly by the moon's gravitational pull
planetary nebula
The outer layers of a low-mass star that have been shed as it reaches
the end of its life.
What are epicycles and deferents?
^Epicycles- the smaller circles; Deferents- the larger circles.
Outer planets
name given to teh four planets beyond mars: jupitar, saturn, uranus and neptune
solar constant
the solar energy received by a square meter of suface oriented at right angles to the direction to the Sun at the Earth's average distance (1 AU) from the Sun; equal to 1372 watts per square meter
Hubbles Law
The further away the object the faster it appears to be moving away from us.
What is the part below the main sequence?
white dwarfs
Suppose you find a rock originally made of potassium-40, half of which decays into argon-40 every 1.25 billion years. You open the rock and find 15 atoms of argon-40 for every atoms of potassium-40. How long ago did the rock form?
5 billion years ago
closest star to the sun
Alpha Centauri, 4.2 ly from Earth
Where are stars born, based on the star life cycle theory?
in collapsing nebulae.
red giant
a large, reddish star late in its life cycle
artificial satellite
Anything we put up there such as the Mars Rover
apparent brightness
the brightness of a star as seen from Earth
irregular galaxies
a galaxy that does not have a regular shape
Terrestrial Planets
4 planets that are close to the Sun and have rocky surfaces
Why do sunspots appear dark?
They actually are fairly bright but appear dark compared to the surrounding material
Period of Rotation
amount of time it takes for the planet to rotate (spin) on its axis one time (a day)
The Local Group is
a cluster of galaxies in which the Milky Way is located. (40)
How were the maria formed?
Molten rock from the Moon's interior flooded the huge basins after large impacts.
name the 4 largest astroids in order (largest to smalles) "all have a diameters of 300km"
ceres, palles, juno, and vesta
what will happen when an asteroid collides with the earth?
probable end of human civilization. devastates the area where it hit, sprays debris out and then heats up atmosphere to a broil and then blocks out the sun, causing an "impact winter" which consists of acid rain. then a long period of high temperature.
Why is gravity considered an inverse squared force?
because it is inversely propotional to the square of the two objects' distances.
whats the difference between rotation and revolution?
rotation is the spinning of a planet on its axis while revolution is the movement of one object around another object
Background Radiation, Quasars, and Red Shifts
What is the evidence for the Big Bang?
what is the rule with two massive objects and their gravity?
for two massive objects gravitational force is proportional to the product of their masses divded by the square of the distance between them.
Which statement about the rotations of Mercury & the Moon is FALSE?
Like our Moon, Mercury does not rotate at all, keeping the same side facing the Sun.
Why do we put telescopes into space?
–Forms of light other than radio and visible do not pass through Earth’s atmosphere.
–Also, much sharper images are possible because there is no turbulence.
The ancient Greeks get a lot of attention for their contributions to science because _________.
they were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural
Does the sun actually rise and set? explain
no, it is the earth's rotation in a 24 hour period that creater day and night
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