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54 terms

Astronomy

Final exam
STUDY
PLAY
Why do we have seasons on earth?
As earth goes around the sun and earth's axis remains pointed toward Polaris, the Northern and Southern hemispheres alternately receive more and less direct sunlight
What is an astronomical unit?
The average distance from earth to the sun
Keplers third law, p2=a3, means that?
All of the above are correct
What conditions are required for a lunar eclipse?
The phase of the moon must be full, and the nodes of the moons orbit must be nearly aligned with earth and the sun
We describe a position on earth's surface by stating its
Latitude and longitude
He discovered that the orbits of planets are ellipses
Kepler
Keplers second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that
A) A planet travels faster when it is nearer to the sun and slower when it is farther from the sun.
What conditions are required for a solar eclipse?
B) The phase of the moon must be new, and the nodes of the moons orbit must be nearly aligned with earth and the sun
Why do we see essentially the same face of the moon at all times
Because the moons rotational and orbital periods are equal
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
If part of the moon passes through earth's umbra, we will see a (n)
Partial lunar eclipse
Which of the following is not a phase of the moon?
Half moon
He discovered that Jupiter has moons
Galileo
According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will
Increase by a factor of 4
Which of the following has your address in the correct order
You, earth, solar system, Milky Way, local group, local super cluster
According to the universal law of gravitation, the force due to gravity is
Inversely proportional to the square of the distance between objects
Why is it summer in the northern hemisphere when it is winter in the southern hemisphere?
The northern hemisphere is tilted toward the sun and receives more direct sunlight
All of the following statements are true. Which one follows directly from Keplers third law?
Venus orbits the sun at a slower average speed than mercury
If your mass is 60kg on earth, what would be you mass on the moon
60kg
If the moon is setting at 6am the phase of the moon must be
full
By locating the north celestial pole in the sky, how can you determine latitude?
The altitude of the NCP is the same as your latitude
All directions are south from the North Pole
true
The seasons on earth are caused by its elliptical orbit around the Sun.
false
What is the range of star masses for high mass stars?
between 8 and 100 solar masses
On a hertzsprung-russell diagram where would we find stars that are cool and luminous?
upper right
what is teh average temperature of the surface of the sun?
6000K
What type of star is our sun?
low-mass star
What happens to energy in the convection zone of the sun?
energy is transported outward by the rising of hot plasma and the sinking of cooler plasma
At the center of the sun fusion converts hydrogen into
helium, energy, and neutrinos
What happens when the gravity of a massive star is able to overcome neutron degeneracy pressure
the core contracts and becomes a black hole
suppose you put two protons near each other because of the electromagnetic force the two protons will
repel each other
the helium fusion process results in the production of
carbon
how does a 1.2 solar mass white dwarf compare to a 1.0 solar mass white dwarf
it has a smaller radius
on a h-r diagram where on the main sequence would we find stars that have the greatest mass?
upper left
the spectral sequence in order of decreasing temperature is
obafgkm
what is a planetary nebula?
the expanding shell of gas that is no longer gravitationally held to the remnant of a low mass star
on a h-r diagram where would we find stars that are cool and dim?
lower right
wihch of the following is closest in mass to a white dwarf?
the sun
which layer of the sun do we normally see
photosphere
white dwarfs are so called because
they are both very hot and very small
which of the following sequences correctly describes the stages of life for a low mass star?
protostar, main sequence, red giant, white dwarf
what kind of pressure supports a white dwarf
electron degeneracy pressure
compared to the star it evolved from, a white dwarf is
hotter and dimmer
why is there an upper limit to the mass of a white dwarf
the more massive the white dwarf the greater the degeneracy pressure and the faster the speeds of the electrons. near 1.4 solar masses the speeds of the electrons approach the speed of light so more mass cannot be added without breaking the degeneracy pressure
which is the following is the most common type of main sequence star
an m star
the core of the sun is at a temperature of about 20,000 k
false
all stars spend approximately the same amount of time on the main sequence
false
in any star cluster stars with lower masses greatly outnumber those with higher masses
true
stars with high masses live longer than stars with lower masses
false
there is no limit to the mass with which a star can be born
false
stars only form in molecular clouds that contain more than 100 times the mass of our sun
false
two stars both lie on the main sequence star x is a spectral type a while star y is spectral type g therefore star x is more massive than star y
true
all stars that become supernovae will leave behind a neutron star
false
spectral type, surface temperature, and color all describe the same basic characteristics of a star
true