Astronomy Exam 2 Flashcards

Terms Definitions
sidereal period
il mondo
Alpha Ursa Major
Magnify angular diameter
day on earth
24 hours
explained types of spectra
radiative energy
energy carried by light
van allen belts surround Earth
radio wave
Electromagnetic radiation with wavelength in the radio part of the spectrum
binary star explosion - periodic
the layer that contains weather
Inner Planets
Venus, Mercury, Earth and Mars
Two moons of Mars
Deimos and Phobos
considered earth as an immovable center of a very small universe
globular clusters
large groupings of older stars
represent the smallest possible unit of a substance which still contains the properties of that substance
All the hydrogen is used up
A gravitationally bound system that consists of stars and star clusters, gas, dust, and dark matter; typically greater than 1,000 light-years across and recognizable as a discrete, single object.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Bright streaks emanating from an impact crater. In reality, they are radial bands of small secondary craters produced by material ejected from a larger impact site.
a single complete turn (axial or orbital)
The third planet from the sun is
Differential Rotation
how stars rotate. Galilieo first measured the rotation rate of the sun
the moon with the most heavily cratered
broad range of wavelengths without interruption...
retrograde motion
apparent backwards motion of the planets in Earth's sky
center of galaxy, football shape, pop ll stars, little gas and dust, supermassive black hole at the center?
solar system
system of eight planets, including Earth, and other objects that revolve around the Sun
Parallax Shift
Apparent motion of a relative object
a group of stars with a pattern
Mass is ____ of Gravatational Force
Directly Proportional
moving around a point outside the body
or orbit
Isaac Newton
pioneered modern studies of motion, optics, gravity and co-discovered calculus
summer solstice
sun at maximum declination (+23.5), first day of summer, about June 21
the explosion of a star, possibly caused by gravitational collapse, during which the star's luminosity increases by as much as 20 magnitudes and most of the star's mass is blown away at very high velocity, sometimes leaving behind an extremely dense core.
where does neutron degeneracy pressure take place
in neutron stars
one of the three volcanic active moons (Jupiter)
the force with which a body presses down on the surface of a world such as earth
Chandrasekhar limit
The maximum theoretical mass of a white dwarf, approximately 1.4 solar masses
The motion of a body around another body is called revolution
an objects ------- tends to keep a moving object continuing in a straight line and a stationary object in space
longitude periasteron
angle between ellipse axis and where you are looking
thermal radiation
radiation in which a photon's energy depends solely on the temperature of the source
The Moon
Appears to move westward each night, due to Earth's eastward rotation. The moon's true motion is eastward.
microwave telescopes are used to detect c____ m____ b____.
cosmic microwave background
Super Nova
large stars, after core collapses and fusion starts again. huge explosion. gives off a lot of energy.
Sun Fusion
Four hydrogen fused together to create 1 Helium, helium less massive than hydrogen that went into it which is mass converted into energy
What is it called when an object orbiting earth is farthest from earth?
does the moon produce light
no it reflects sunlight
large planets of low density are classified as
jovian planets
H-R diagram
used to classify stars and to understand how stars change over time.
in order to study gamma rays, ultra rays, ultra red, you must be where?
having or representing the earth as a center:
grid of arcs
divides the earth, since the Earth's surface is approximately a sphere use these to define locations
Which moon in the solar system shows a dense atmosphere?
the 2 days of the year on which neither hemisphere is tilted toward or away from the sun
Binary star
a system of two stars that revolve around each other under their mutual gravitation
angle between an object in the sky & the horizon
black hole
an object so massive and dense theta even light cannot escape its gravity
solar noon
sun's highest point in the sky during the day
If a moon is getting bigger is it waxing or wanning
the diea that the matter in the universe is evenly distributed without a center or an edge, is often called the c_____ p____.
cosmological principle
stability of nucleus
number of nuetrons vs number of electrons
lenticular galaxy
a large group of stars that together make a shape that has a central bulge but no spiral arms
a large cloud of gas and dust in space, spread out in an immense volume
What causes the tides?
The moon's gravitational pull on earth creates two bulges on Earth- one that is closest and one that is furthest from the moon.
low mass star stages:
nebulae, main sequence, red giant stage, yellow giant, red super giant
What is the name of the time of year when the the earth is farthest from the sun?
93 million miles
How far is an astronomical unit in miles.
the period of time that it takes for a planet to make a complete revolution around the sun
Annual Solar Eclipse
Occurs when the moon's umbra does not reach the Earth's surface
Milky Way
the galaxy to which the Sun and Earth belong; seen as a pale, glowing band across the sky
tropic of cancer
a line of latitude about 23 degrees North of the equator
A Lunar Eclipse
Earth's shadow cast on the moon causes this?
look-back time
The amount by which we look into the past when we look at a distant galaxy. A time equal to the distance to the galaxy in light-years. (p. 288)
physical evidence of spherical earth
People living in the south see southern constellations higher above the horizon than people living in the north, the shadow of the Earth on the Moon during a lunar eclipse is round, matter settling onto Earth would naturally shape itself into a spherical shape
Irregular galaxy
A galaxy that does not fit into any of the other major categories in the Hubble classification scheme.
Characteristics of the moon
dry, airless, on forth the size of earth, no water, no atmosphere, variations in temperature
About how many stars are visible on a dark night, away from city lights?
a couple thousand
Spacecraft:Cassini / Huygens Probe
- robots sent to study Saturn and moons
- Cassini Orbiter: to study atmosphere, rings of Saturn, and magnetics of planet
- Hyugens Probe studied Titan moon
Why are these outer planets grouped together? What characteristics do they share?
Gaseous (with rock/ice cores), Thick atmospheres, Many moons, Lower density, Large size, Far from the Sun, Relatively far apart from each other
30 doradus or the trantula nebula
the glowing region of new star formation near the site of
the explosion of SN 1987A.
Observations of very remote thermonuclear supernovae indicate that: (a) when the universe was half its present age, light travelled faster than it does now. (b) when the universe was half its present age, it was contracting. (c) the expansion of the unive
(d) the expansion of the universe is accelerating.
Why does the sun appear to move?
Because as earth rotates eastward, the sun appears to move westward across the sky.
what is a planetary nebula?
the expanding shell of gas that is no longer gravitationally held to the remnant of a low mass star
Does Venus have a magnetic field? Why or why not?
No because the rotation is so slow.
What happend to the Radiation and Matter?
There was a crossover at around 10^3.0 and both Matter and Radiation Density has been decreasing.
sags from weight, absorbs lights, and suffers from chromatic aberration
why is it difficult to make a large thick lens?
If your mass is 60 kilograms on Earth, what is it on the Moon?
60 kilograms, because mass does not depend on gravity.
a star is twice as massive as the sun. Will its lifespan be longer, shorter, or that same as that of the sun? Why?
it will be shorter because if the star is bigger it uses its fuel faster
Means Sunlight
Venus moon
Has no moons
Crustal dating
radioactive dating
radioactive elements half-life's = the time for the material to decay to a lighter atom
the suns luminosity
3.826X10^26 J/s
radio telescopes
aka "big dishes"
how fast something is moving
Saturn unusual motion
similar to jupiters
reflecting telescope, eyepiece through mirror
The spinning of the Earth
material of Saturn's rings
water ice
How many Apollo missions successfully landed on the Moon?
By studying a star's __________, scientists can determine elements found in the star's atmosphere.
saturn rings
jovian planets have ring systems
Earth Centered Universe - Greek astronomer, wrote a book that combined all of the anciet knowledge of astronomy
Astronomical unit.
One AU is the distance from the Earth to the Sun.
Newton's Second Law may be stated:
Which planet also has retrograde rotation
The almost mass less "ghost" particles which don't interact with other matter.
Moons surface features
Craters, Highlands, Maria (Lunar plains)
minor features: wrinkle ridges, scarps, domes, rilles
Define: Aperture
The diameter of a telescope objective.
Jupiter smooth ice crust liquid ice ocean
(astronomy) any of the small solid extraterrestrial bodies that hits the earth's atmosphere
electrons spiral around magnetic field because they can't go through it
synchotron radiation
synodic period
the time interval between successive similar alignments of a celestial object with respect to the Sun
a large celestial body that is composed of gas and that emits light
Radio Waves
the longest wavelengths of the electromagnetic spectrum, from ~10cm-100km.
What planet is 4th from the sun?
farthest from the sun; occurs July 4
Greek philosopher. A pupil of Plato, the tutor of Alexander the Great, and the author of works on logic, metaphysics, ethics, natural sciences, politics, and poetics, he profoundly influenced Western thought. In his philosophical system, which led him to criticize what he saw as Plato's metaphysical excesses, theory follows empirical observation and logic, based on the syllogism, is the essential method of rational inquiry.
Point at which a planet appears opposite the Sun in our sky.
When activity slows down areas on photosphere become cooler, and darker
How does a planet shine?
By reflected light
dark, flat regions on the moon's surface
: a sub-division of an arc-minute (1/21,600th of a circle) into 60 equal finer divisions. Equal to 1/60th of an arc-minute, 1/3,600th of a degree, or 1/1,296,000th of a complete circle. It is symbolized by a double accent or quote following the value, as in 8” (eight seconds). It is an angular measurement and not related to any unit of time.
solar eclipse
moon directly between the sun and earth, moon must be at a node
what knd of spectrum light emmited by the surface of the sun that goes through its atmosphere have
Upper M-S stars have a convective core and a radiative outer region, just the
opposite of the Sun
the angular distance east and west of the Prime Meridan
Jovian planets were formed beyond the _____ line to form large, ____ planetesimals.
frost, icy
seventh planet from the Sun; is large and gaseous, has a distinct bluish-green color, and rotates on an axis nearly parallel to the plane of its orbit
blue stars
hot young stars with hydrogen & helium
A magnetic storm on the sun's surface which appears as a dark spot. When sun is more luminous there are more.
all stars begin life as ________. A large amount of gas and dust in space spread out in an immense volume.
number of seconds needed for the wave to repeat itself at any given point in space
Earth's Magnetosphere
protect us from charged sun particles, can create aurorae
A solid which the atoms are arranged in repeating patterns
Hubble's Law
galaxy clusters move in an ordered manner with a redshift motion even though the galaxies within them do not. the greater the distance, the greater the redshift. recessional motion proves galaxy is expanding!
Law: rate at which galaxy recedes/distance from us
arcminute (arcmin)
(') unit used for measuring angles. 1/60 of a degree of arc
TF Like dark matter, the newly found dark energy will also retard the expansion of the universe
A slow periodic wobble in the Earth's axis caused by the gravitational pull of the Sun and Moon
To complete the moon's phases takes __ days.
Synodic Month
is responsible for the moon's phases, because the Moon's appearance depends on the position of the Moon with respect to the Sun as seen from the Earth
Neutron Star
a star that has collapsed under its own gravity
Winter solstice
December 21st each year and is the shortest day of the year in the Northern Hemisphere
North celestial pole
the location on the celestial spehere directly above the Earth's northern rotation pole
star categories (size)
red giant, medium sized star, white dwarf, neutron star
by high-speed electrons that pump up oxygen and nitrogen molecules in the atmosphere, causing them to fluoresce like a cosmic neon sign
what causes auroras?
the moon is larger than a half but smaller than a full moon
lunar eclipse
the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon
Doppler shift
change in the apparent frequency of a wave as observer and source move toward or away from each other
astronomical unit
the distance from Earth to the Sun, approximately 150 million kilometers
elliptical galaxies
80% of all galaxies, most are dwarfs, the super large ones eat others
Project Gemini
second stage in the U.S. program to reach the Moon, in which an astronaut team connected with another spacecraft in orbit
the path that an object takes as it moves through space, usually around another object.
focus, foci
the two points from which the ellipse is generated; for all points on the ellipse, the sum of distances to the two foci are the same
Chemical and size twin of Earth. A hot burning hell of immense proportion
quantum mechanics
The study of the behavior of atoms and atomic particles. (p. 105)
the polestar or North Star, a star of the second magnitude close to the north pole of the heavens, in the constellation Ursa Minor
What does Apollo mean?
The god of the sun and poetry
Local Space Environment of Earth
Magnetosphere= magnetic field & solar wind
Composition of Stars
Characteristic set of lines seen by a spectroscope compare the set of lines to find out what a star is made of
Binary Cluster System
By observing the motion of galaxies in a cluster, we can calculate how much mass is needed to keep the cluster from flying apart
maunder minimum
a period of few sunspots and low solar activity that occurred between 1640 and 1700
full phase
the phase of the moon at which the bright side of the mood is the face turned towards the earth
Which of the following objects (A-D) are accelerating? A. an object at rest / B. an object in motion in a straight line at a constant speed / C. an object in motion in a straight line with increasing speed / D. an object moving in a circle at constant spe
Both C and D.
stage 2 of a stars life is
protostar-gravity pulls the particals of hydrogen and dust from a cloud
solution to olbers's paradox
if the universe had a beginning then we can only see light from galaxies that has had time to travel to us since the beginning of the universe
The type of comet tail that has an
emission-line spectrum is the
gas or plasma tail
How to compute diameter with parallax
diameter = distance x angular diameter/ 57.3
As material flows into a black hole
the material will experience time dilation and the material will become hotter.
Why is there an extreme difference in the temperature of the moon from daytime to nighttime?
Because there is no atmosphere
Present abundances like deuterium
tell us what was going on very early in the evolution of the universe because deuterium is not formed in stars.
How long ago did the Sun begin to shine?
4.6 billion years ago
What is the Life Cycle of a medium/small Star?
Nebula, Protostar, Giant, White dwarf, Black dwarf
Explain where the energy comes from in proton-proton chain fusion reactions
The energy comes from the proton-proton chain giving off two protons when transitioning from helium-3 to helium-4
C. The core contracts, raising the temperature and increasing the size of the region of hydrogen shell-burning.
Just as a low-mass main sequence star runs out of fuel in its core, it actually becomes brighter. How is this possible?
A. Helium fusion gives more energy than hydrogen fusion does, based on masses.
B. Its outer envelope is stripped away and we see the brilliant core.
C. The core contracts, raising the temperature and increasing the size of the region of hydrogen shell-burning.
D. It explodes.
E. It immediately starts to fuse helium.
How does a star keep orbiting another star in a binary star system?
Gravity from star's mass pulls on other star, keeps it in orbit
What is the difference between population I and II stars?
I are young and in the spiral arms, II are old and in the halo or bulge
White dwarfs form when
A) a massive (≈ 10M⊙) star explodes as a supernova.
B) a low mass (≈ 1M⊙) star's iron core collapses.
C) a low mass star loses its outer layers as a planetary nebula.
D) two red dwarf stars collide.
E) a low mass s
C) a low mass star loses its outer layers as a planetary nebula.
metallic hydrogen
waxing crescent
a total shadow
surface rocks are primarily
stage 5
violent surface activity
shadow during total eclipse
sun is considered a ___
What is the smallest planet?
Luminous cloud of particles surrounding the nucleus of a comet
the attractive force between objects
what do some quasars project
plate motions
slide laterally, collide together, move apart
Annie Jump Cannon
Harvard Observatory "computer"
number of galaxies in universe
100 billion
the visible surface of the sun
Strong Nuclear force of nature
Binds nucleus
The distance between successive wave crests defines the ________ of a wave.
asteroid-sized bodies that contain ice & travel in elongated orbits around Sun. absorbed energy from sun and melt & evaporate the ice and producing a huge cloud and a tail of gas and dust that reflect sunlight while near the Sun.Meteor showers occur when earth passes through the debris trail.

tail points away from sun
of light, the effect that different colors are bent by different amounts when passing from one substance to another
the apparent change in a stars brightness position or color due to the motion of gases in the earths atmosphere
seasonal changes effect the heating of surface by ______________
twice-yearly point at which the sun reaches its greatest point
electromagnetic radiation
radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge
celestial sphere
Imaginary sphere surrounding Earth to which all objects in the sky were once considered to be attached.
element that most stars are made of
particle model
exert a pressure called radiation pressure on matter
the most common gaseous element found in stars is _______.
Planck's law
Mathematical description of the energy radiated at different wavelengths by a blackbody
A small rocky body orbiting the sun
apparent pathway of the Sun against the stars as seen from Earth - a projection of the Earth's orbit
celestial poles
intersection of Earth's Pole with the Sky
A distant galaxy that emits a huge amount of energy; Produced by gas falling into a supermassive black hole in the center of the galaxy
coriolis effect
deflection of wind due to earth's rotation
sun spots
black spots on the sun's surface (photosphere), cooler than the surrounding area because of the sun's magnetic field that keeps in heat and light
convection zone
area just below surface that energy moves and undulates sun surface
tilt of the orbital plane, earth is set at zero
Developed the first modern theory of a sun-centered universe
Big bang theory
the theory that the universe originated 12-15 billion years ago from the cataclysmic explosion of a small mass of matter at extremely high density and temperature
Spring Tide
the tide with the greatest difference between high and low tide that occurs when the sun and the moon are aligned in a line with Earth
absorbtion spectrum
a continuous spectrum with some bands of light absorbed by going through a gas
Reflecting telescope
forms an image by reflecting light with mirrors
Electromagnetic Force
The source of all chemistry and biology. Forms atoms, molecules and cells, and is the cause of most "contact forces" while it acts at infinite distances
the different shapes of the moon you see from earth are called...?
Saturn's rings are in small rings (may be due to shepherding moons)
terrestrial vs jovian
Terrestrial: rocky, similar to earth. Jovian: Gasseous, similar to Jupiter.
Atoms of the same element but w/a different # of neutrons
o Big hot balls of gas (about 75% hydrogen and 25% helium)
o Nuclear fusion is converting H into He in the core.
o Are the factories in which elements other than H and He are made.
• Grouped into galaxies.
• There are about 100 billion per galaxy. (10^11).
• There are at least 100+ billion galaxies. (10^11).
Is this the order of a Solar eclipse true or false - Sun, Earth, Moon?
Things can fall into a black hole, but nothing can get out
Main Sequence
Where stars spend most of their time; most stars are in the main sequence
Brightness is
the amount of energy striking per unit area per unit time of some light sensitive surface (Brightness is what we can measure directly)
Temperature and weather of Earth
Greenhouse effect- atmosphere retains IR Radiation (heat), O-zone layer absorbs UV radiation from outer space; weather and clouds mainly within 10km of Earths surface
elliptical galaxy
a galaxy shaped like a round or flattened ball, generally containing only old stars
Type II Supernova
a supernova explosion in which the degenerate core of an evolved massive star suddenly collapses and rebounds
Cosmic microwave background
low level radiation coming from all directions in space as a consequence of the Big Bang
light year
the distance that light travels in a vacuum in 1 year
What causes things to orbit each other?
gravity & inertia
21 cm radiation is a result of an electron in hydrogen flipping its spin direction
21 cm radiation is a result of an electron in hydrogen flipping its spin direction
mean solar day
the interval of light between two successive nights; the time between sunrise and sunset:
apparent magnitude
the brightness of a star as seen from Earth
solar nebula
cloud of gas and dust from which the sun and the rest of the solar system formed
fall equinox
sept 21, equal day & night, DIRECT RAY HITS THE EQUATOR
orbital energy
an object that gains ___ moves into an orbit with a higher average altitude (escape velocity)
Standard Candle
If we know how luminous an object is, we can use it to measure distance as a...
Jupiter going slower around the sun is due to what law?
kepler's 3rd law
Kepler's first law
Each planet's orbit around the Sun is an ellipse, with the sun as one focus of that ellipse.
(elliptical vs circular)
Note: most planets have low eccentricity
The time required for the sun to complete one orbit around the center of our Galaxy is about: (a) 3x10 to the fifth years. (b) 0.24 Gyr. (c) 4.6 Gyr. (d) 15 Gyr.
(b) 0.24 Gyr
the Earth spins on its axis.
Constellations appear to move across the sky at night because
Penumbral Lunar Eclipse
an eclipse of the Moon in which the Moon passes through the Earth's penumbra but not through its umbra
Which of the following are terrestrial planets?
Mercury, Venus, Earth, and Mars
Law of Conservation of Angular Momentum
An object's angular momentum cannot change unless it transfers angular momentum to or from another object
What are the disadvantages of refracting telescopes?
Blurry, must replace glass ever so often.
After a few million years of He burning you get what?
Triple process.... 3He --> C
Blue Shift and the Red Shift
Blue shift occurs because the light waves from star appear to be shorter as star moves toward the earth.
Red Shift occurs because the light waves from the star appear to be longer as the star moves away
(14) According to the International Astronomical Union (IAU), what is the official definition of a planet now and why does this definition exclude Pluto from having the status of a planet?
The members of the IAU defined a planet as a body that orbits a star, is large enough to be round, and has cleared other bodies out of its neighborhood. This excludes Pluto from being a planet because it is surrounded by other "bodies" and is unable to clear a big enough path for itself.
At New Moon, the Moon looks:
The Moon cannot be seen at New Moon.
How do you get a nova?
From a white dwarf in a detached binary system
The spectral sequence in order of decreasing temperature is..
OBAFGKM (Oh Be A Fine Guy Kiss Me)
side view if the milky way
a narrow disk with a bulge in the middle
a planet is more likely to keep its atmosphere from escaping into space if its upper atmosphere is?
cold and the gravitational field is strong
carry most of the energy of the solar wind because they are so much more massive than an electron. proton flux is the same in the slow and fast winds
what do protons in the solar wind do?
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