AST 2003
which of the following studies is best suited to astronomical observations that fall into the category called time monitoring ?
studying how a star's brightness varies over a period of 3 years
what do we see in this photo?
Neptune
rank these objects from left to right based on their mass, HIGHEST to LOWEST
sun, Jupiter, earth, mars, mercury, pluto
rank these objects from left to right based on their size, LARGEST to SMALLEST
sun, Jupiter, earth, mars, mercury, pluto
the stars in our sky twinkle in brightness and color because of ________
turbulence in the Earth's atmosphere
which of the following effects is caused by atmospheric turbulence ?
twinkling of stars
two hypothetical discoveries in part a deal with moons that, like earth's moon, are relatively large compared to their planets. which of these best explains why finding 1 planet with such a moon is consistent with the nebular theory, while finding 6 planets with such moons is not consistent ?
unusually large moons form in giant impacts, which are relatively rare events
which planet listed has the most extreme seasons ?
uranus
which of the following forms of light can be observed with telescopes at sea level ?
visible light radio waves
the diffraction limit is a limit on:
a telescope's angular resolution
what is the angular resolution of the human eye?
about 1 arcminute, or 1/60 of a degree
the Hubble Space Telescope obtains higher-resolution images that most ground-based telescopes because it is:
above Earth's atmosphere
which technology can allow a single ground-based telescope to achieve images as sharp as those from the Hubble Space Telescope?
adaptive optics
when did the objects that we now see as asteroids and comets form in the solar system ?
after solid particles condensed from the gas but before the planets finished forming
Venus has a higher average surface temperature than mercury. why ?
because its surface is heated by an extreme greenhouse effect
as you'll learn in later chapters, the lack of volcanoes is a result of the moon's relatively small size. but what explains the other two items- the moon's synchronous rotation and gradually increasing distance from earth ?
both are results of tidal interactions between the moon and earth
in what way is venus most similar to earth ?
both planets are nearly the same size
if our eyes were sensitive ONLY to x-rays, the world would appear ________ .
dark because x-ray light does not reach earth's surface
if you had only one telescope and wanted to take both visible-light and ultraviolet pictures of stars, where should you locate your telescope ?
in space
the James Webb space telescope is designed primarily to observe _______ .
infrared light
rank these materials from left to right based on their temperature at which each would condense into a solid, HIGHEST to LOWEST
metals, rock, hydrogen compounds, hydrogen and helium gas
this diagram shows the approximate depths to which different wavelengths of light penetrate Earth's atmosphere. why does it show an airplane?
most of the infrared spectrum can be observed from an airplane that flies above most clouds
compared to the distance between earth & mars, the distance between jupiter and saturn is ________ .
much larger
which of the following is NOT a major pattern of motion in the solar system?
nearly all comets orbit the Sun in the same direction and roughly the same plane
which of these is NOT a major pattern of motion in the solar system ?
nearly all comets orbit the sun in the same direction and roughly the same plane
what substances existed as solid flakes within the innermost regions (within about the inner 0.3 AU) of the solar system before planets began to form ?
none
what process created the elements from which the terrestrial planets were made?
nuclear fusion in stars
the "giant impact hypothesis" refers to the idea that _______ .
our moon formed when a mars-size object collided with the young earth
the nebular theory holds that _______ .
our solar system formed from the collapses of an interstellar cloud of gas & dust
based on what the nebular theory tells us about the formation of our own solar system, what do these theories predict for the possibility of other planetary systems ?
planetary systems should be common
rank these objects from left to right based on their average distance from the sun, FARTHEST to CLOSEST
pluto, saturn, Jupiter, mars, earth, mercury
notice the numbered points on this photo of the Gemini North reflecting telescope. Where is the secondary mirror located?
point 3
what can you conclude from studying this graph ?
potassium-40 has a half-life of 1.25 billion yrs
which of the following statements about Mars is NOT true?
we could survive on Mars without spacesuits, as long as we brought oxygen in scuba tanks
the Chandra x-ray observatory must operate in space because ______ .
x-rays do not penetrate earth's atmosphere
what is the primary reason that we launch x-ray telescopes into space rather than building them on the ground ?
x-rays from space do not reach the ground
consider the first major feature (orderly motions). which of these correctly describe patterns of motion in our solar system ?
~all planets orbit the sun in nearly the same plane ~planets have nearly circular orbits ~the sun and most of the planets rotate in the same direction that the planets orbit
jovian;
--numerous orbiting moons -extensive ring systems - low average density -primarily composed of hydrogen, helium, and hydrogen compounds
Saturn's Rings
-are NOT solid; they are made of countless small chunks of ice and rock, each orbiting like a tiny moon
Mercury
-avg distance from Sun: 0.387 AU -axis tilt: 0.0 -mass: 0.055 -radius: 2,440 km -avg density: 5.43 g/cm3 -orbital period: 87.9 days -rotation period: 58.6 days -made of metal and rock; large iron core -desolate, cratered; long, tall, steep cliffs -very hot and very cold; 425 C (day) and -170 C (night)
Venus
-avg distance from Sun: 0.723 AU -axis tilt: 177.3 -mass: 0.82 -radius: 6,051 km -avg density: 5.24 g/cm3 -orbital period: 225 days -rotation period: 243 days -nearly identical in size to Earth; surface hidden by clouds -hellish conditions due to an extreme greenhouse effect -even hotter than Mercury: 470 C day and night
Earth
-avg distance from Sun: 1 AU -axis tilt: 23.5 -mass: 1 -radius: 6,378 km -avg density: 5.52 g/cm3 -orbital period: 1 year -rotation period: 23.93 hours -an oasis of life -the only surface liquid water in the solar system -a surprisingly large moon
Mars
-avg distance from Sun: 1.52 AU -axis tilt: 25.2 -mass: 0.11 -radius: 3,397 km -avg density: 3.93 g/cm3 -orbital period: 1.88 years -rotation period: 24.6 hours -looks almost Earth-like, but don't go without a spacesuit! -giant volcanoes, a huge canyon, polar caps -water flowed in the distant past
Uranus
-avg distance from Sun: 19.2 AU -axis tilt: EXTREME 97.4 -mass: 14.5 -radius: 25,559 km -avg density: 1.32 g/cm3 -orbital period: 83.8 years -rotation period: 17.2 hours -smaller than Jupiter/Saturn; much larger than Earth -made of hydrogen and helium gas and hydrogen compounds (H2O,NH3,CH4) -moons (24) and rings
Neptune
-avg distance from Sun: 30.1 AU -axis tilt: 29.6 -mass: 17.1 -radius: 24,764 km -avg density: 1.64 g/cm3 -orbital period: 165 years -rotation period: 16.1 hours - similar to Uranus (except for axis tilt) -many moons (13), including Triton
Pluto
-avg distance from Sun: 39.5 AU -axis tilt: 112.5 -mass: 0.0022 -radius: 24,764 km -avg density: 2.0 g/cm3 -orbital period: 248 years -rotation period: 6.39 days -much smaller than other planets: dwarf planet -icy, comet-like composition -its moon Charon is similar in size (1 moon)
Jupiter
-avg distance from Sun: 5.2 AU -axis tilt: 3.1 -mass: 318 -radius: 71,492 km -avg density: 1.33 g/cm3 -orbital period: 11.9 years -rotation period: 9.93 hours -much farther from Sun than inner planets -mostly hydrogen and helium; no solid surface -300 times more massive than Earth -many moons (61) and has rings
Saturn
-avg distance from Sun: 9.54 AU -axis tilt: 26.7 -mass: 95.2 -radius: 60,268 km -avg density:0.70 g/cm3 -orbital period: 29.4 years -rotation period: 10.6 hours -giant and gaseous like Jupiter -spectacular rings -many moons (31), including cloudy Titan -Cassini spacecraft currently studying it
Jupiter's Moons
-can be as interesting as planets themselves, especially Jupiter's four Galilean moons: ->Io: active volcanoes all over ->Europa: possible subsurface ocean ->Ganymede: largest moon in solar system ->Callisto: a large, cratered "ice ball"
reflecting telescopes:
-most commonly used by professional astronomers today -the Hubble Space telescope -world's largest telescope
Sun
-radius: 108 + (+ means radius of the Earth) -mass: 333,000 + (+ mass of the Earth) -99.9% of the solar system's mass -composition: 98% hydrogen and helium -converts 4 million tons of matter to energy each second
terrestrial:
-small size -located within the inner solar system -solid, rocky surface
refracting telescopes:
-the world's largest is 1 meter in diameter -very large telescopes become "top-heavy" -incoming light passes through the glass -Galileo's telescope
fill in the blank (3)
1) visible, infrared, radio 2)infrared 3)x-ray, ultraviolet
vocabulary dragging order (7)
1)angular resolution 2)reflecting telescopes 3)spectrographs 4)interferometry 5)grazing incidence 6)light-collecting area 7)refracting telescopes
vocabulary dragging order (5)
1)imaging 2)spectroscopy 3)time monitoring 4)atmospheric turbulance 5)light pollution
vocabulary dragging order (8)
1)solar nebula 2)planetesimal 3)heavy bombardment 4)accretion 5)solar wind 6)condensation 7)frost line 8)radiometric dating
vocabulary dragging order for planets (8)
1)uranus 2)venus 3)mercury 4)mars 5)jupiter 6)earth 7)neptune 8)saturn
suppose you have a rock that, when it solidifies, contains 1 microgram of a radioactive isotope. how much of this isotope remains after five half-lives ?
1/32 microgram
the light-collecting area of an 8-meter telescope is _____ times that of a 2-meter telescope
16
how much more light does an 8 meter telescope gather than a 2 meter telescope ?
16 times as much
suppose you find a rock and measure that 12.5% of the original uranium-235 still remains it, while the other 87.5% has decayed into lead-207. about how old is the rock ?
2.1 billion years
approximately what is the half-life of uranium-235 ?
700 million years
this famous photograph taken by the voyager spacecraft shows ____
Earth as viewed from the outskirts of the solar system
what is the Oort cloud?
It's not really a cloud at all, but rather refers to the trillion or so comets thought to orbit the Sun at great distances
What do astronomers mean by light pollution?
Light pollution is light from human sources that makes it difficult to see the stars at night.
what object is shown in this photo?
Mars
which of the following lists the planets of our solar system in the correct order from closest to farthest from the Sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
what planet is this, and how do you know?
Saturn, because of its colors and bright, wide rings.
in this photograph, the large and bright object in the sky is ____
a comet
suppose you have a camera attached to a telescope, & you want to record an image of a faint galaxy. which of these will help the most?
a lot of pixels and a long exposure time
the verdict at the end of the extraordinary claims box says "likely correct, though may never be possible to prove definitively." in the context of models, which of the following best explains this verdict ?
a model that precisely reproduces major characteristics of the moon would seem more likely correct, but we can't go back in time to see that it actually happened that way
consider the hypothetical discovery from part a reading: "a star's 5 terrestrial planets orbit in the opposite direction of its 3 Jovian planets." this discovery would be inconsistent with the nebular theory holds that _______ .
all the planets formed in a rotating, disk shaped nebula
suppose you view the solar system from high above Earth's North Pole. which of the following statement s about planetary orbits will be true?
all the planets orbit counterclockwise around the Sun
interferometry uses two or more telescopes to achieve:
an angular resolution equivalent to that of a much larger telescope
as discussed in the extraordinary claims box, when the giant impact idea was first proposed, it was generally thought to be so unlikely that it wasn't seriously considered until decades alter, after the apollo missions to the moon. what key piece of scientific understanding was missing that made it seem so unlikely when first proposed ?
an understanding of the number and size of leftover planetesimals in the early solar system
what are the two most important properties of a telescope ?
angular resolution light-collecting area
where would you expect terrestrial planets to form in the solar nebula ?
anywhere between the innermost regions (within about the inner 0.3 AU) and the frost line
which of the following is NOT a real difference between asteroids and comets?
asteroids orbit the Sun, whereas comets just float randomly around in the Oort cloud
which of these is NOT a real difference between asteroids and comets ?
asteroids orbit the sun, whereas comets just float randomly around in the oort cloud
Why was it advantageous for the Voyager mission to consist of flybys rather than orbiters?
each individual spacecraft was able to visit more than one planet
why was it advantageous for the voyager missions to consist of flybys rather than orbiters ?
each individual spacecraft was able to visit more than one planet
this famous photograph taken by the voyager spacecraft show _______ .
earth as viewed from the outskirts of the solar system
which of the following is NOT true of Mercury?
even on Mercury's night side, the temperature is hot enough to melt lead
which of the following types of robotic mission to a planet is generally the cheapest?
flyby
which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light ?
getting an image of the same angular requires a much larger telescope for radio waves than for visible light
which of the following is thought to explain many of the "exceptions to the rules" of our solar system ?
giant impacts
rank these materials from left to right based on their abundance in the solar system, HIGHEST to LOWEST
hydrogen and helium gas, hydrogen compounds, rock, metals
rank these materials from left to right based on their distance from the sun at which they could condense into a solid in the solar nebula, FARTHEST to CLOSEST
hydrogen compounds, rock, metals
the Cassini spacecraft:
is orbiting saturn
what is the purpose of interferometry ?
it allows two or more small telescopes to achieve the angular resolution of a much larger telescope
how is einstein's famous equation, E=mc^2 important in understanding the sun ?
it explains the fact that the sun generates energy to shine by losing some 4 million tons of mass each day
which of the following statements about Pluto is true?
it has more in common with other icy objects in the Kuiper belt than it does with the jovian planets
which of the following is NOT an advantage of the Hubble space telescope over ground-based telescopes ?
it is closer to the stars
according to present understanding, which of these statements about solar wind is NOT true ?
it is even stronger today than it was when the sun was young
which of these best describes what we mean by the focal plane of a telescope ?
it is the place where, if we mounted film or an electronic detector, we could get a clear image of an object viewed through the telescope.
in what direction does Uranus orbit the Sun?
it orbits the Sun in the same direction as the other planets
why has nasa sent recent orbiters to mars on trajectories that required them to skim through mar's atmosphere before settling into their final orbits ?
it saves money because the spacecraft uses atmospheric drag to slow down rather than needing to carry enough fuel to slow by firing rocket engines
which of these statements was true beyond the frost line (but not inferior to it) ?
it was cold enough for hydrogen compounds to condense into ices
imagine that an alien spaceship crashed onto earth. which would most likely be true ?
it would crash in the ocean
the jovian planets in our solar system are _______ .
jupiter saturn uranus neptune
rank these stages from left to right based on when they occurred, FIRST to LAST
large cloud of gas and dust contraction of solar nebula condensation of solid particles accretion of plantesimals cleaning the solar nebula
we expect a scientific theory to be able to make predictions that can be tested. which of these is a prediction of the nebular theory that has been verified by observations ?
many stars should have planets
the terrestrial planets in our solar system are ______ .
mercury venus earth mars
the planets in our solar system in the correct order from "closest to farthest" from the sun
mercury venus earth mars jupiter saturn uranus neptune
astronomers have begun to build instruments to detect "cosmic messengers" that are not forms of light, such as neutrinos, cosmic rays, and gravitational waves, because they _____
provide information about distant objects that we cannot obtain from light
What kinds of light are these telescopes designed to detect?
radio waves
When your eye forms an image, the _____ plays a role analogous to the detector in a camera.
retina
when your eye forms an image, the _____ plays a role analogous to the detector in a camera
retina
when your eye forms an image, the _____ plays a role analogous to the detector in a camera .
retina
the jovian planets are thought to have formed as gravity drew hydrogen and helium gas around planetesimals made of _____ .
rocks, metals, & ices
what substances were found in the innermost regions (within about the inner 0.3 AU) of the solar system before planets began to form ?
rocks, metals, hydrogen compounds, hydrogen, & helium, all in gaseous form
mars has two moons, phobos & deimos, that are most similar in character to __________ .
small asteroids
this x ray image was taken by the Chandra x-ray observatory. without knowing anything more about the object that is shown, what can you conclude from looking at this image
some parts of the object emit more x-rays than others
which of these is NOT a major difference between the terrestrial and jovian planets in our solar system ?
terrestrial planets contain large quantities of ice and jovian planets do not
in the context of studying major bodies of our solar system, which category of object does our moon best fit ?
terrestrial world
what do you see orbiting Earth in this photo?
the Hubble Space Telescope
which of the following telescopes benefits most from adaptive optics ?
the Keck I telescope on Mauna Kea
which of the following telescopes benefits most from adaptive optics?
the Keck I telescope on Mauna Kea
which of the following statements about our Sun is NOT true?
the Sun's diameter is about 5 times that of Earth
what does angular resolution measure ?
the angular size of the smallest features that the telescope can see
all statements are true. which one counts as an "exception to the rule" in being unusual for our solar system ?
the diameter of earth's moon is about 1/4 that of earth
why does the sun's image look distorted in shape at sunset ?
the distortion arises because of the way air affects the paths of light
consider these "rocky asteroids are found primarily in the astroid belt and kuiper belt, while icy comets are found primarily in the oort cloud." what is wrong with this statement ?
the kuiper belt contains icy comets, not rocky asteroids
suppose that two stars are separated in the sky by 0.01 arc-second, and you observe them with a telescope that has an angular resolution of 1 arc-second. what will you see ?
the light from two stars will. be blended together so that they look like one star
what do you mean when we say that a nucleus undergoes radioactive decay ?
the number of protons or neutrons (or both) in the nucleus changes
suppose you have two small photographs of the moon. although both look the same size, when you blow them up to poster size one of them still looks sharper & the other becomes more fuzzy looking. which of the following statements is true ?
the one that still looks sharp at large size has better (smaller) angular resolution than the one that looks fuzzy
The angular separation of two stars is 0.1 arc-seconds and you photograph them with a telescope that has an angular resolution of 1 arc-second. What will you see ?
the photo will seem to show only one star rather than two
the angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?
the photo will seem to show only one star rather than two
this is a photo of a satellite dish on a house. In essence, the dish is _____
the primary mirror of a radio telescope
this photo shows a satellite dish on a house. in essence, the dish is ________ .
the primary mirror of a radio telescope
which one of these is NOT one of the four major features of the solar system ?
the solar system contains eight planets plus dwarf planets (ceres, pluto, eris)
what is the primary basis on which we divide the ingredients of the solar nebula into the four categories hydrogen/helium, hydrogen compounds, rock, & metal ?
the temperatures at which various materials can condense from gaseous form to solid form
according to the nebular theory of solar system formation, what key difference in their early formation explains why the Jovian planets ended up so different from the terrestrial planets ?
the terrestrial planets formed inside the frost line of the solar nebula and the jovian planets formed beyond it
which of the following in NOT a reason why telescopes tend to be built on mountaintops that are relatively far from cities and are in regions with dry climates ?
the thin air on mountaintops makes the glass in telescopes mirrors less susceptible to warping
this photo shows a single star photographed by the Hubble Space Telescope. Why doesn't the star appear as a single, sharp point of light?
the wave properties of light make this type of blurring an unavoidable feature of any telescope
why are astronomers interested in building observations capable of detecting neutrinos, cosmic rays, & gradational waves ?
these things are NOT forms of light, and therefore can provide different types of information than light about objects that emit them
in which these ways are pluto & eris more like comets than like any of these terrestrial or jovian planets ?
they are made mostly of rock and ice
consider the hypothetical discovery from part a reading: "beyond its jovian planets, a star has two ice-rich objects as large as Mars." This discovery is consistent with the nebular theory, because this theory predicts that _________ .
this might have happened in our own solar system if it had taken longer for the solar wind to clear the solar nebula
consider the second major feature (two types of planets). which of these statements are true for the terrestrial and jovian planets in our solar system ?
~jovian planets are longer in mass than terrestrial planets ~jovian planets orbit father from the sun than terrestrial planets ~jovian planets are larger in size than terrestrial planets ~jovian planets have more moons than terrestrial planets
while we may never be able to prove that our moon really formed in a giant impact, which of these would give scientists greater confidence that the model is correct ?
~observing evidence of recent giant impacts in other solar systems that are currently in the process of formation ~creating more sophisticated models of the giant impact that correctly predict many detailed characteristics of the earth and moon ~finding evidence that other gimlet impacts occurred in our solar system, with a total number of impacts consistent with what models of solar system formation lead us to expect
all of these statements are true. which of these are considered to be "exceptions" to the general trends described by the first three major features of the solar system ?
~our moon has a diameter more than 1/4 the diameter of earth ~uranus rotates with an axis tilt that lies nearly in the ecliptic plane ~venus rotates in a direction opposite to the rotation of the other terrestrial planets
the solar system contains vast numbers of small bodies, which we call asteroids when they are rocky and comets when they are icy. these small bodies are concentrated in the regions of the solar system that we call _______ .
~the oort cloud ~the kuiper belt ~the asteroid belt
what are four key features of our solar system that any theory of solar system formation must be able to explain ?
~there are clear patterns to the rotation and orbits of large bodies in the solar system ~there are a few notable "exceptions to the rules" ~planets fall into two major categories ~there are vast numbers of asteroids and comets