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Astro test 2
Terms in this set (76)
Dissociation is the process in which
the bonds between an atom and a molecule are broken
when an atom loses an electron, it becomes
When an atom absorbs a photon containing energy, any of the following can happen except which?
an electron moves from an upper energy level to a lower one
the study of energy levels in atoms is called
How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
it releases a photon equal in energy to its own energy drop
If you heat a gas so that collisions are continually bumping electrons to higher energy levels, when the electrons fall back to lower energy levels the gas produces
an emission line spectrum
when white light passes through a cool cloud of gas, we see
an absorption line spectrum
Spectra from neutral atoms compared with spectra from ionized atoms of the same element
have different sets of spectral lines
how does the spectrum of a molecule differ from the spectrum of an atom?
a molecule has additional spectral lines due to changes in its rotational and vibrational energies
If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects?
the one with the large redshift is moving away from us faster than the one with the small redshift
Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.)
the blue star has a hotter surface temperature than the red star
Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes?
the two stars will look like a single point of light
Which is a principal advantage of CCDs over photographic film?
CCDs capture a much higher percentage of incoming photons
What are the 2 principal advantages of telescopes over eyes?
telescopes can collect far more light with far better angular resolution
What does the diffraction limit of a telescope mean?
the best angular resolution the telescope can achieve with perfect optical quality and in the absence of atmospheric distortion
which of the following could not be determined by an observation that uses only spectroscopy?
the size of a distant galaxy
what is meant by spectral resolution?
it is a measure of how close two spectral lines can be distriguished
which of the following are true about images captured with x-ray telescopes?
they are always displayed in false color
What do astronomers mean by light pollution?
light used for human activities that brightens the sky and hinders astronomical observations
What causes stars to twinkle?
bending of light rays by turbulent layers in the atmosphere
what is the purpose of adaptive optics?
to eliminate the distorting effects of atmospheric turbulence for telescopes on the ground
what is an artificial star?
a point of light in Earth's atmosphere created by a laser for the purpose of monitoring atmospheric fluctuations
which of the following is not a good reason to place observatories on remote mountain tops?
to be able to observe at radio wavelengths
Why do astronomers need different telescope designs to observe across the electromagnetic spectrum?
Photons of different energy have different wavelengths, some of which are not accessible on Earth's surface and require different collection strategies
which wavelength regions cannot be studied with telescopes on the ground?
Ultraviolet and X-Ray
Telescopes operating at this wavelength must be cooled to observe faint astronomical objects.
What does the technique of interferometry allow?
It allows 2 or more telescopes to obtain the angular resolution of a much larger telescope
The largest effective telescope, created by radio interferometry, is the size of
In what wavelength range was interferometry first routinely used?
How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope?
four times (square of the ratio)
the diffraction limit is a limit on a telescope's...
the hubble space telescope is able to obtain higher resolution images than ground based telescopes because it is...
above Earth's atmosphere
what does it mean if you see the color red in an image from the Chandra X-ray telescope?
it depends. colors are chosen arbitrarily to represent something about the recorded x-rays
the twinkling of stars is caused by
motion of air in our atmosphere
To achieve the same angular resolution as a visible light telescope, a radio telescope would need to be
where should you put a telescope designed for ultraviolet observations?
in Earth's orbit
Which technology can allow a ground based telescope to achieve images as sharp as those from the hubble space telescope?
suppose you look at 2 stars that are separated in the sky by 0.1 arcseconds using a telescope with an angular resolution of 0.5 arcseconds. what will you see?
one point of light that is the blurred image of both stars
what is not true about patterns of motion in our solar system?
planets all rotate in the same direction
Astronomers have decided that, rather than being a planet, Pluto is really just a large member of
The Kuiper belt
What are Jovian planets largely made of?
Hydrogen and helium
What is not true of all inner planets?
They (do not) all have substantial atmospheres
The planet closest in size to Earth is...
Do all planets orbit at the same speed?
Which planet has a ring system?
What observation indicates that Mars may have been suitable for life in the past?
There is liquid water as well as a significant number of dried up river beds
Which part of the solar system is farthest from the sun?
the Oort cloud
How does the Sun's mass compare with that of the planets?
it is a thousand times greater than all of the planets combined
Which planet has the highest average surface temperature, and why?
Venus, because of its dense carbon dioxide atmosphere
Which is the densest planet in the solar system?
How are asteroids different from comets?
Asteroids are rocky bodies and denser than comets, which are made of icy material
What is the origin of almost all the large moons around jovian planets?
they were formed by condensation and accretion in a disk of gas around the planet
Observation of young stars (as well as theory) tell us that when the sun was younger, solar wind...
was stronger than it is today
What has not been detected around other stars in the galaxy that is present in our solar system?
at first, the sun's present day rotation seems to contradict the prediction of the nebular theory because...
the sun should have been rotating fast when it formed, but the actual rotation is fairly slow
Why does the sun rotate slowly today?
the sun slowed due to the transfer of angular momentum into charged particles
According to the nebular theory, what are asteroids and comets?
leftover planetesimals that never accreted into planets
According to the nebular theory, how did the Kuiper belt form?
It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet
According to the solar nebula theory, why do we find some exceptions to the general rules and patterns of the planets?
Most of the exceptions are a result of giant impacts
The water we drink comes from...
comets that impacted Earth
how long did the heavy bombardment phase of the solar system last
several hundreds of millions of years
What cannot be explained by a giant impact event?
the orbit of Triton in the opposite direction of Neptune's rotation
What fact of the solar system cannot be predicted by the nebular theory?
the equal number of terrestrial and jovian planets
The age of the solar system can be established by radioactive dating of
the oldest meteorites
What percentage of the mass of the solar nebula consisted of elements other than hydrogen and helium?
Where did the elements heavier than hydrogen and helium come from?
they were produced inside the stars
Why did the solar nebula heat up as it collapsed?
as the cloud shrank, its gravitational potential energy was converted to kinetic energy and then into thermal energy
Why did the solar nebula flatten into a disk?
it flattened as a natural consequence of collisions between between particles in the spinning nebula, changing random motions into more orderly ones
what happened during the accretion phase of the solar system?
particles grew by colliding and sticking to one another
Why do all planets orbit the Sun in the same direction and nearly the same plane?
The laws of conservation of energy and conservation of angular momentum ensure that any rotating, collapsing cloud will end up as a spinning disk
list the ingredients of the solar nebula from highest to lowest percentage of mass in the nebula
Light gasses, hydrogen compounds, rocks and metals
what percentage of the solar nebula's mass consisted of hydrogen and helium gasses?
what percentage of the solar nebula's mass consisted of rocky material?
What kind of material in the solar nebula could remain solid at temperatures as high as 1,500 K?
What was the frost line of the solar system?
the distance from the Sun where temperatures were low enough for hydrogen compounds to condense into ices, between the present-day orbits of Mars and Jupiter
Why are the inner planets made of denser materials than the outer planets?
in the inner part of the nebula only metals and rocks were able to condense because of the high temperatures, whereas hydrogen compounds, although more abundant, were only able to condense in the cooler regions farther from the center