final Flashcards
the strip of the sky through which the sun, moon, and planets appear to move in the course of a year is:
the zodiac
an idealized object that does not reflect or scatter any radiation that hits, but simply absorbs every bit of radiation that falls on it:
a blackbody
when we see an eclipse of the moon, the earth is between the sun and the moon (T/F)
true
Newton showed that to change the direction in which an object is moving, one needs to apply:
force
If you could see the new moon, at what time of day would it rise?
sunrise
the strength of gravity is inversely proportional to the mass (T/F)
false
what phase is the moon during a lunar eclipse
full
what phase is the moon during a solar eclipse
new
a planet in the solar system whose period is 1 year is what distance from the sun
1 AU
when the moon rises at 9pm, what phase is it
waning gibbous
in stars moving away from us, the spectral line shows a blue shift (T/F)
false
if the earth had no tilt, how would this affect our view solar and lunar eclipses
we would see then the way we normally do
an icy dwarf planet orbits the sun with a period of 20 years, whats the semi-major axis of its orbit in AU
7.4
a reflector doesn’t have to deal with the twinkling of stars, a refractor does (T/F)
true
The absorption lines of helium have the same wavelength as its emission lines (T/F)
true
on the celestial sphere, halfway between the celestial poles lies the…
celestial equator
the slow tipping of earths axis in a circle with a period of about 26,000 years is called a
precession
13.8 billion in scientific notation
1.38 x 10^10
which of the following is an important part of the reason it is hotter during the summer in North America than during the winter?
the suns rays hit earth more directly in the summer and spread out less
if you want to locate someone precisely on the surface of the Earth, you specify her exact latitude and longitude. if you want to locate a star precisely on the sky you need to specify its exact
right ascension and declination
when a planet, in its orbit, is closer to the sun it
moves faster than avg
the scientist who formulated the 3 laws of planetary motion by analyzing the data on the precise location of planets in the sky
johannes kepler
someone observing the night sky in boston will NEVER get to see the
south circumpolar zone
the moon shows retrograde motion (T/F)
false
what kind of rays are you likely to detect from earths surface
radio waves
ice planet Hoth has the same radius but half the earths mass, if you weigh 100 lbs on earth, how much would you weigh on Hoth?
50 lbs
why do astronauts float around the international space station instead of falling?
the station is falling around earth and everything aboard is in free fall
who used epicycles to explain retrograde motion
ptolemy
from a city in the US, where in the sky would you look to see a star that is not turning with the motion of the sky in the corse of the night
at the north celestial pole
what time is it when the new moon is highest in the sky
noon
Wien’s law relates the wavelength at which a star gives off the greatest amount of energy to the stars
temperature
the South celestial pole and North celestial pole lie in the sky directly above
the earths axis
first discovered the moons of jupiter
galileo
x-rays have the light with the highest energy on the electromagnetic spectrum (T/F)
true
the shortest night in mass is on the
summer solstice
if the earths rotation axis was not tilted, winter and summer would be extremely different (T/F)
false
analyzing the light in the spectrum of a star can tell astronomers the stars temperature, what elements are in it, and its speed to or away from us (T/F)
true
the moon revolves around the sun once every
month
earths period of rotation is equal to 1 year (T/F)
false
when a small asteroid collides with a planet the acceleration of the asteroid is grater than the acceleration of the planet (T/F)
true
distance travelled by light or by an object moving with a constant speed is equal to speed multiplied by
time
the star closest to the north celestial pole
polaris
the reason for seasons is the varying distance between the sun and the earth (T/F)
false
on the autumn equinox, our days and nights are the same length (T/F)
true
the peak wavelength of light from the sun is about 500 nm, is a star with a peak wavelength of 1500 nm hotter or colder than the sun
colder
the type of spectral feature usually observed from a hot gas with no star behind it along the line of sight is the absorption line (T/F)
false
who found that gravity could account for the motion of the planets
newton
if a galaxy of stars is moving towards us, the light in its spectrum will show a red shift when compared to the lines we measure in such a spectrum on earth (T/F)
false
an asteroid is in circular orbit of 3 AU from the sun. its period of revolution is how many years
√27
when a small amount of gas is heated up in a transparent container until the gas glows, it generally gives off an emission line spectrum (T/F)
true
a light year is
the distance light travels in one year
6400 in scientific notation
6.4 x 10^3
in the north hemisphere, the altitude of the north star is always roughly equal to the
latitude of the observer
gamma-ray astronomy is only done from space (T/F)
true
where are you on earth if polaris is on your horizon
the equator
a star is 230 light years away. the light we see tonight from a star that left it
230 years ago
if earths orbit changed to be a perfect circle around the sun so the distance never changes over the course of a year, how does this affect our experience of seasons
essentially experience them the same way we do now
the moon is believed to have formed by a collision with earth and a mars-sized object (T/F)
true
the inner planets are made of mostly rock and metal because
it was so hot where the inner planets formed that lighter material evaporated
the planet with no liquid water now seen but sinuous channels appear to be streambeds of ancient rivers
mars
in addition to 100’s of smaller objects that have been discovered in the Kuiper belt, astronomers were surprised to find
larger bodies as big as pluto (aka dwarf planets)
balls of rocks and ice in the Kuiper belt are…
plutoids
what evidence shows the surface of europa being relatively young
very few craters on the surface compared to callisto and ganymede
planets with rings
jupiter, saturn, uranus, neptune
main constitutes of mars
rock and iron
Our best evidence and theoretical calculations indicate that the solar system began with a giant spinning
system of gas and dust that scientists call
the solar nebula
the moon and earth are about the same age (T/F)
true
Which of the planets once had large amounts of carbon dioxide in the atmosphere but now stores it in limestone and rock?
earth
motion of the crustal plates is driven by convection in the earths upper mantle (T/F)
true
According to the theory of continental drift, Africa and South America drifted apart about how many years ago?
200 million
Astronomers have discovered many circumstellar disks around other young stars that resemble what we think our solar system looked like as it was forming (T/F)
true
What is the reason for the difference between typical meteors and typical meteorites?
the only meteors that do not burn up in the atmosphere are large ones, these are asteroid fragments
terrestrial planets
mercury, venus, earth, mars
jovian planets
jupiter, saturn, uranus, neptune
the primary greenhouse gases in earths atmosphere are
carbon dioxide and water vapor
___ has the largest volcanoes in the solar system
mars
When the planets were first forming in our solar system, the much greater heating experienced by the giant planets caused them to lose most of their lighter elements (T/F)
false
the diameter of jupiter is ___ times the diameter of earth
10
the satellite which has the thickest atmosphere
titan
charon is the moon that belongs to…
pluto
What are the main constituents of the Earth’s core, mantle, and crust?
rock & iron
When a rotating cloud contracts, it
spins faster & flattens
The Earth’s atmosphere is primarily composed of
nitrogen and oxygen
the planet with the hottest avg surface temp
venus
typically small pebbles aka
meteoroids
More than 75% of the known asteroids are found
in a belt between mars and jupiter
planets are thought to have formed
when the sun was formed
Although we have studied asteroids with our telescopes, no spacecraft has visited or flown by an asteroid so far (T/F)
false
which part of a comet is the densest
the nucleus
saturn emits more energy than it receives from the sun (T/F)
true
Which of the following characteristics do all four terrestrial planets have in common?
they all have solid
surfaces with signs of geological activity on them
venus does not have a satellite (T/F)
true
The lakes found in the north polar region of Titan are filled with liquid
methane
Most meteors that you see as streaks in the sky are
small pebbles that are debris
from comets
Saturn is the largest planet in the solar system. (T/F)
false
jovian planets rotate slower than terrestrial planets (T/F)
false
The more craters we can count on the surface of a moon, the older that surface must be. (T/F)
true
one way to determine the age of a world that does not have a solid surface is to count the craters (T/F)
false
the cloud that collapsed to form the solar system was mostly
hydrogen
first asteroid confirmed to have a moon was
ida
On which planet, besides the Earth, do we still see a high level of geological activity on the surface today?
venus
Most of the carbon in our bodies originated in
the core of a red giant star
When any star first arrives on the main sequence, it will always be located at the same exact point on the
H-R Diagram (at the same luminosity and temperature (T/F)
false
The density of the Sun is closest to the density of
water
In a stable star, the gravitational forces are balanced by
thermal pressure
Stars that lie in different places on the main sequence of the H-R diagram differ from each other mainly by having different:
masses
Suppose that the Sun were suddenly replaced by a black hole of exactly the same mass. Then the planets of our solar system would continue to orbit as usual. (T/F)
true
When an astronomer describes the luminosity of a star she is studying, she is talking about:
how much energy the star gives off each second
A black hole is likely to be the end of stellar evolution for what type of main-sequence star?
O
main sequence stars are rare in the galaxy (T/F)
false
One billion years from now the Sun will be a
main sequence star
Compared with Earth’s diameter, the Sun’s diameter is about 100x larger (T/F)
true
most abundant element in the sun is…
hydrogen
how hot is the suns photosphere
6000K
the photosphere is the part where the light comes from that we see when we look (T/F)
true
on the H-R diagram, the sun is on the main sequence (T/F)
true
a supernova occurs at the end of the life of a star with
10 times the mass of our Sun or more (T/F)
true
How much more luminous is a star that is the same size but two times hotter than our Sun?
16
the # of sun spots get smaller and larger over the course of __ years
11
The typical lifetime of a star is a few thousand years. (T/F)
false
the Sun’s energy is made through chemical reactions (T/F)
false
a star with an apparent magnitude of -1 looks the brightest in the sky (T/F)
true
Really massive stars differ from stars with masses like the Sun in that they
can fuse elements beyond carbon and oxygen in their hot central regions
Measurements show a certain star has a very high luminosity (100,000 times the Sun’s) while its temperature
is quite cool (3500 K). How can this be?
it must be quite large in size
The Sun is a stable star in which
gravity balances the force from pressure
The Sun rotates at different rates at different latitudes on the Sun. (T/F)
true
What incident in a massive star’s life sets off (begins) the very quick chain of events that leads to a supernova
explosion?
the fusion of iron
How much more luminous is a star that is 4 times larger but the same temperature as our Sun?
16
The mass of a main-sequence star is half the mass of the Sun. Its luminosity is 1/10 the luminosity of the
Sun. Its lifetime in years is about
50 billion years
More massive stars spend less time on the main sequence in the H-R Diagram than low-mass stars do (T/F)
true
The fastest-spinning neutron star known rotates about
700 times a second
pulsars show high temp fusion reactions (T/F)
false
Compared to stars with cooler surfaces, stars with hot surfaces are
bluer
How many times more massive is the Sun than the Earth?
300,000
The event in the life of a star that begins its expansion into a giant is
almost all the hydrogen in its core that was hot enough for fusion has been turned into helium
The event horizon of a black hole
is the point from within which light cannot
escape
Compared to the surrounding photosphere, sunspots are
cooler
What type of stars will spend the longest time (the greatest number of years) on the main
sequence?
K
A Type O main-sequence star is cooler than a type K main-sequence star. (T/F)
false
The density and temperature in the solar corona are much higher than in the photosphere. (T/F)
true
What can escape from within a black hole?
neither light nor matter
The central star in a planetary nebula is an old
white dwarf
The granulation pattern that astronomers have observed on the surface of the Sun tells us that:
hot material must be rising from the suns hotter interior
The most stable (tightly bound) atomic nucleus in the universe is:
iron
Why are astronomers much more interested in the luminosity of a star than its apparent brightness?
because the luminosity tells us how bright a star really is, while apparent brightness only tells us how bright
it happens to look from Earth
What graduate student working with Antony Hewish first discovered pulsars?
jocelyn bell
