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ASTR 101 Final - Flashcards
Scientific notation is used in science because... |
It makes it easy to write big or small numbers all astronomical distances are expressed in metric units it makes conversions between units easy ALL OF THE ABOVE |
The average distance from the Earth to the sun is.. |
I AU |
The sun is... |
A star; I AU from earth; more than 100 times the diameter of earth; ALL OF THE ABOVE |
A galaxy contains: |
gas, dust, stars, and a lot of dark matter |
The Milky way Galaxy... |
Contains about 100 billion stars |
2.9 x 10^7 is the same as... |
29 million |
Arrange the following in order from smallest to largest...Kilometer, light-year, yard, AU |
Yard, Kilometer, AU, Light-year |
It takes 1.3 seconds to travel from the moon to earth and 8 minutes to travel from the sun to the earth. Which of the following statements is true? |
The sun is 370 time further from earth than the moon |
If light takes 8 min to travel from the sun to earth and 5 hr to travel from the sun to pluto, what is the distance from the sun to pluto? |
37.5 AU |
The speed of light is 3.0x10^5 km/sec, and it takes 1.0 sec for light to travel from the moon to earth. From this information, what is the distance to the moon? |
390,000 km |
If the distance to nearest star is 4.2 light-years, then |
The light we see left the star 4.2 years ago |
The Milky way galaxy is... |
A spiral galaxy; part of a cluster of galaxies, about 75,000 light years in diameter; ALL OF THE ABOVE |
Which sequence is correct from smallest to largest: earth, galaxy clusters, milky way, solar system |
Earth, solar system, milky way, galaxy clusters |
How is a planet different from a star |
Planets reflect light while stars produce their own |
If the distance from the sun to the earth is roughly 15 meters, then the distance from the earth to the moon would be... |
smaller than your hand |
Seen from the northern latitudes, the star Polaris.. |
is always above the northern horizon |
The celestial equator is |
a line around the sky directly above Earth's equator; the dividing line between the north and south celestial hemispheres; A AND B |
The ______ is the point on the celestial sphere directly above any observer |
Zenith |
Constellations names are in... |
Latin |
Most star names, such as Aldebaran and Betelgeuse are.. |
Arabic |
The magnitude scale |
can be used to indicate the apparent intensity of a celestial object |
The apparent visual magnitude of a star is a measure of the star's... |
intensity |
The star Vega has an apparent magnitude of .03 and the star HR 4347 has an apparent magnitude of 4.87. It has been determined that both are the same distance from earth. What does this tell us? |
Vega must produce more energy than HR 4374 |
The ______ of an object depends on the diameter of the object and the distance to the object |
apparent diameter |
An observer's nadir is... |
the point directly opposite the observer's zenith |
A(n) _____ is one-3,600th of a degree |
second of arc/arc-second |
The Big Dipper is... |
an asterism |
Procession of the rotation axis of earth is caused by... |
the force of gravity from the sun and moon on earth's equatorial bulge |
An observer in the northern hemisphere watches the sky for several hrs. Due to the motion of earth, this observer notices that the stars near the north celestial pole appear to move... |
counter clockwise around the celestial pole |
You live at a latitude of 73*N. What is the angle between the northern horizon and the north celestial pole? |
73* |
You live at a latitude of 39*S. What is the angel b/w the southern horizon and the south celestial pole? |
39* |
If the north celestial pole appears on your horizon, what is your latitude/ |
0* |
which star on the right would appear brightest to an observer?[TABLE] |
alpha CMa |
Based on the info int he table to the right, what is the ratio of the intensity of Delta Dra to that of Nim? [TABLE] |
100 |
Which star in the table would not be visible to the unaided eye of an observer on earth? |
Nim |
Star A has an apparent visual magnitude of 13.4. Star B = 15.4. Star A is _____than star B |
6.3 times brighter |
Polaris is a 2nd magnitude star, and Phi Pegasi is about 16 times fainter. What is magnitude of Phi Pegasi? |
5 |
Which of the following correctly describes the relationship between stars and constellations? |
Every star is located in a constellation |
How much of the night sky is north of the celestial equator? |
Exactly 1/2 |
If the sun passes directly overhead on at least one per day per year, then, |
you are within 23.5* latitude of the equator |
If you are standing at the earth's north pole, which of the following would be located at the zenith? |
The north celestial pole |
For stars in the same constellation, they |
may actually be very far away from each other |
During June the north celestial pole points towards polaris but during the Dec it points |
still towards polaris |
If the earth's period of rotation is doubled, but the period of revolution stayed the same... |
the night would be half as long |
The [DIAGRAM] shows 3 app. locations along western horizon. Which indicates sunset on 12-21 at a latitude of 48*S? |
1 |
[DIAGRAM] sunset on 6-21 for 37*N |
3 |
[DIAGRAM] sunset 6-21 at latitude 77*N |
The sun will not set on June 21 at the latitude |
[DIAGRAM] sunset at vernal equinox at 48*S |
2 |
The ecliptic is... |
The centerline of the zodiac; the projection of earth's orbit on the sky; the apparent path of the sun around the sky; ALL OF THE ABOVE |
At what two celestial locations do the celestial equator and ecliptic coincide? |
Vernal equinox autumnal equinox |
On the vernal equinox, the sun is... |
on the celestial equator and moving north wrt the equator |
A solar or lunar eclipse will occur.. |
when the sun is near the line of nodes of the moon and the moon is new or full |
The sideral period of hte moon... |
is about 27.32 days long; is the period of time for the moon to orbit earth wrt the stars; BOTH A AND B |
without the moon, which of the following are true? |
... |
The moon has an angular diameter of .5*. What is the moon's angular diameter in minutes of arc? |
30 |
If the plane of the earth's equator were not tilted wrt to the ecliptic plane... |
the daylight period of earth would be the same year-round; there would be no seasonal changes; earth's poles wold not experience six month long nights; ALL OF THE ABOVE |
The phase of the moon on a particular night is determined by... |
the relative positions of th sun, earth, and moon |
On a clear night when an observer in LA sees a 1st quarter moon, an observer in london would see... |
a first quarter moon |
The moon's angular diameter in our sky is measured to be .5*. From this we can find... |
diameter of the moon if we know the moon's distance |
The lowest amount of solar energy per square meter is incident upon the surface of earth in the northern hemisphere on or about... |
December 21, the winter solstice |
Which of the following did not accept a heliocentric model for the universe? |
Tycho |
Parallax is... |
the apparent motion of an object due to the motion of the observer |
The copernican system was no more accurate than the ptolemaic system in predicting the positions of the planets because... |
the copernican system included uniform circular motion |
Galileo's telescopic discoveries of mountains on the moon and spots on the sun were controversial because they suggested that the sun and moon... |
were not perfect spheres |
Tycho's universe was the same as the copernican universe except that... |
earth did not move |
Tycho brahe's greatest contribution to astronomy was... |
his 20 years of careful observations of the planets |
When we say that the gravitation is universal, we mean that... |
it is a property of all matter |
Newton concluded that some force had to act on the moon because... |
a force is needed to pull the moon away from straight-line motion |
Kepler's second law implies that... |
a planet should move at its greatest speed when it is closest to the sun |
Kepler's first law of planetary motion implies that... |
the distance between the planet and the sun changes as the planet orbits the sun |
Gravity obeys an inverse square relation. This statement implies that the force due to gravity between two masses... |
will decrease as the square of the distance b/w the two masses increases |
The force due to gravity between two objects depends on... |
I & III; the mass of each object; the distance b/w the two objects |
An object has been located orbiting the sun at a distance from the sun of 65 Au; what is the app. orbital period? |
524 years |
Saturn is on average 10 AU from the sun. What is the app orbital period of saturn? |
32 years |
In pre-copernican astronomy, it was almost universally believed that... |
the earth was the center of the universe |
When mars is located directly behind the earth wrt the sun in its orbit, it is... |
at the midpoint in the sky bewteen east and west at midnight |
The greatest inaccuracy in copernicus' model of the solar system was that the planets... |
travel in circular orbits with uniform motion |
Which of the following statements describes Kepler's 3rd law of planetary motion? |
The larger the orbit, the longer its orbital period |
_____ has wavelengths that are longer than visible light |
Infrared radiation |
____ have wavelengths that are shorter than visible light? |
I, II, IV; Gamma-rays, ultraviolet light; x-rays |
The energy of a photon |
is inversely proportional to the wavelength of the light |
Long wavelength visible light |
will appear red in color to the average human eye |
Photons of blue light |
have a greater energy than photons of red light |
A nanometer is... |
a unit of length |
What is the relationship between color and wavelength for light? |
wavelength increases from blue light to red light |
In which way does a photon of blue light NOT differ from a photon of red light? |
speed |
The neutral hydrogen atom consists of |
one proton and one electron |
The process of removing an electron from a stable nucleus is known as... |
ionization |
The two most abundant elements in the sun are... |
hydrogen and helium |
Which of the following can be determined by using the Doppler effect? |
I, III, IV; the speed at which a star is moving away from an observer; the radial velocity of a star; the speed at which a car is traveling toward an observer |
[DIAGRAM] shows a light source, gas cloud, and 3 diff straight lines. Which line would you see an absorption spectrum? |
3 |
The [TABLE] shows spectral types of five stars; which would have the lowest surface temp? |
Cet |
The [TABLE] lists spectral types. Which star would have the greatest surface temp? |
Per |
Two stars of the same spectral class must have the same... |
temperature |
The radiation emitted from a star has a maximum intensity at a wavelength of 300 nm. What is the temp? |
10,000 K |
At what wavelength would a star radiate the greatest amount of energy if the star has a temp of 60,000 K |
50 nm |
The sun has a temp of app 5800 K. At what wavelength does the max energy radiated by the sun occur? |
520 nm |
One star has a temp of 30,000 K and another 60,000K. How much more energy/sec will the hotter star radiate? |
625 times |
One star has a temp of 10,000K and another 5,000K. How much more energy/sec will the hotter star radiate? |
16 times |
How much energy is radiated each second by one square meter of a star whose temp is 10000 K? |
5.67x10^8 J |
The H delta line has a wavelength of 410.2 nm in the lab. If it appears in a star spectrum at 410.0, what is the radial velocity? |
146 km/sec toward the observer |
The H[delta] line has a wavelength... |
146 km/sec TOWARD observer |
The Hy line has a wavelength... |
346 km/sec AWAY from observer |
What is the order of star colors with increasing temperature |
Red, yellow, blue |
Each element has its own set of characteristic absorption lines because |
electron energy levels differ for each element |
The Doppler effect states that the motion of any object can... |
shift the wavelength of spectral lines |
Granulation is caused by |
rising gas below the photosphere |
Most of the light we see coming from the sun originates in the |
photosphere |
The sun creates its energy by the process of |
nuclear FUSION |
The chromosphere of the sun |
is hotter than the photosphere |
The diagram at the right shows a plot of temp of the sun... |
2300 km; other question is 9000 K |
Sunspots |
are cooler than their surroudings |
The ___ is/are the hot gases that are the moving extension of the sun's corona |
Solar wind |
If a sunspot=4500 K and surroundings=5800, how many times brigther? |
2.8 |
If the spectrum of a sunspot shows that it has a maximum at 650 nm, waht is temp of sunspot |
4600 Kq |
What are three layers of suns atmosphere, in order of increasing distance from the surface? |
Photosphere, chromosphere, corona |
A star's luminosity depends only on the star's |
temperature and diameter |
In an HR diagram, stars with smallest radius are found in the ___ of the diagram |
lower left |
We know that giant stars are larger in diameter than the sun because |
they are more luminous but have the same tempreautre |
Which star in the diagram is most like the sun? |
HR 5337 |
Which star in the diagram has the greatest surface temp? |
Alnilan |
Which of the stars in the diagram has the largest absolute visual magnitude? |
Sirius B |
Which of the following stars in most dense? |
a white dwarf |
If a star has a parallax of .02 sec of arc, then its distance is... |
50 pc |
If a star with an absolute mag of -5 has an apparant mag of +5, then its distance is.. |
1000 pc |
Which star in the table above would appear the faintest in the night sky? |
65 Tau |
Which star in the table above has the greatest luminosity |
58 Ori |
Which star in the table above is closest to the earth? |
HR 2491 |
Which star in the table above has the greatest surface temperature? |
HR 4621 |
If you compare two stars... |
the one with the smaller absolute magnitude will always have greater luminosity |
Interstellar gas clouds may collapse to form stars if they.. |
encounter a shock wave |
The average star spends ___ of its lifetime on the main sequence |
90% |
What causes the outward pressure that balances the inward pull of gravity in a star? |
the outward flow of energy |
The free-fall contraction of a molecular cloud... |
can be initiated by shock waves from supernovae |
Which of the following is not evidence of the existence of an interstellar medium? |
molecular bands in the spectra of cool stars |
Due to the dust in the interstellar medium, a star will appear to an observer on earth to be.. |
fainter and cooler than it really is |
The extinction of starlight due to the interstellar medium... |
I & IV; is the greatest in the ultraviolet, is caused by dust particles |
Stars are born in |
dense molecular clouds |
while on the main sequence, a star's primary energy source comes from |
nuclear FUSION |
What force(s) are responsible for the collapse of an interstellar cloud? |
gravity |
Why do higher mass stars live shorter lives on the main sequence than lower mass stars? |
high mass stars burn through their nuclear fuel faster |
As a star exhausts hydrogen in its core, it.. |
becomes cooler and more luminous |
A Type Ia supernova is believed to occur when.. |
a white dwarf exceeds the chandrasekhar limit |
A type-II supernova.. |
C&D; is characterized by a spectrum that shows hydrogen lines; occurs when the iron core of a massive star collapses |
Which of hte following is not a characteristic of hte stars of the disk component of our galaxy? |
randomly inclined orbits |
Younger stars have more heavy elements because... |
the heavy elements were made in previous generations of stars |
Radio maps of our galaxy show spiral arms because |
the gas in spiral arms is denser |
_____ of the milky way contains mostly population II stars and globular clusters |
The spherical component |
___in other galaxies shoudl contain luminous O and B stars if they are like the milky way |
the spiral arms |
The period-luminosity relation is useful in determining... |
the distance to globular clusters that contain cepheid variables |
____is believed to dominate the mass content of the galaxy |
dark matter |
Population II stars ... |
III & IV; are primarily old low mass stars; are located in globular clusters |
The orbits of population I stars |
I & III; are confined to disk of the galaxy; are nearly circular |
The traditional theory states that the galaxy formed... |
as a large spherical cloud of gas that was rotating very slowly |
A Type-II cepheid has been located in a distant globular cluster with a period of 10 days; what is the abso. mag? |
-1 |
Which of the following can't be associated with the spiral arms of a galaxy? |
metal poor stars |
What behavior do galactic rotation curves exhibit to suggest the existence of dark matter? |
large velocities are seen at large distances from the galactic center |
A mega-parsec is equivalent to.. |
3,260,000 light years |
The hubble law is a relation between a galaxy's |
distance and recession velcoity |
Gravitational lensing |
occurs when light passes near a massive object and is deflected by the object's gravitational field |
the look-back time is... |
a&b; the time it takes for the light from an object to reach earth; numerically equal to the distance in light-years |
Most of hte mass of a galaxy is contained in the |
dark matter of a galaxy |
___galaxies have no obvious spiral arms or nucleus |
Irregular |
Suppermassive black holes are believed to be located at the center of many galaxies because |
the orbital motion of material near the center is very fast and indicates a very massive core |
what is the hubble's constant essentially a measure of? |
the expansion of the universe |
what is the primary factor in determining the classification for an elliptical galaxy? |
shape |
what distance method is used to calibrate the hubble constant? |
supernova observations |
the hubble time is |
an estimate of the age of the universe based on hubble's constant |
when a proton and an antiproton collide |
they destroy each other and produce energy in the form of gamma rays |
as the universe cooled, it eventually reached a temp.... |
recombination |
what was the temp when the recombination took place? |
about 3000 K |
In 1998 is was announced that the expansion of the universe is accelerating. what does this imply? |
a force exists that we knew nothing about that causes the expansion |
the cosmic background radiation comes from a time in the evolution of the universe... |
when electrons began to recombine with nuclei to form atons |
whether the universe if open,closed, or flat depends on... |
density |
current evidence suggests that the universe is... |
flat, infinite, and accelerating in its expansion |
what observational evidence supports the fact that our universe is expanding? |
redshift of galaxies |
where did the cosmic microwave background (CMB) come from? |
photons released when electrons and nuclei combined for the first time |
why is the CMB so cold if the early universe was so hot? |
the expansion of the universe has redshifted those photons to an effectively cooler temperature |
what observation has prompted astronomers to ponder the possible existence of dark energy? |
supernovae appear fainter than expected at large redshifts |
microlensing refers to |
gravitational lensing by stellar object with Einstein rings around microseconds |
Plants around stars other than the sun |
have been found by astronomers using several different methods |
What limitation(s) make it impossible to travel between stars? |
II & III; the tremendous distance; the finite speed at which objects travel |
how are galaxies distributed in the universe? |
they are group in clusters and superclusters, connected by chains, surrounding large empty voids |
which of the following is not a method for searching planets around stars other than the sun? |
accurate measurement of the temperature of the stars |