Astronomy Ch 5: ALL OFFICIAL HOMEWORK QUESTIONS
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.
What is a CCD?
An electronic imaging detector
The _______ ________ of the Hubble Space Telescope is better for shorter (bluer) wavelengths of light than for longer (redder) wavelengths of light
Angular resolution
At least these wavelengths, it is necassary to build telescopes with a very large light collecting________ to obtain maps of sufficient sensitivity to faint cosmic signals
Areas
The effect of a cool, dilute gas between an observer and a continuous hot source is that_____
Dark absorption lines will appear in the spectrum
If our eyes were ONLY sensitive to X-ray, how would the world appear?
Dark because x-rays light does not reach the earth's surface.
In the _____ ______ a red shift of spectral lines shows us the source is recording from us
Doppler Affect
The observed spectral lines of a star are all shifted towards the red end of the spectrum This is an example of..
Doppler Effect
The ingredients of a typical comet's nucleus are most likely..?
Dust and rocky particles trapped in methane, ammonia, and water ice
Radio waves go through? and can be done on earth
Dust and the earth's atmosphere
Pluto is different from the outer planets in all of the following ways except which one?
Its surface temperature is very cold.
These planets have rings around the equators and at least 8 moons
Jovian
What type of planet is this? -accreted from ice planetesmals -formed in regions cold enough for freezing water -formed in region of the solar system w. lower orbital speeds -large moonds formed surrounding disks of material -ejected icy planestimals that are not oort comets
Jovian
Which planet contains a mass = to all planets combined
Jupiter
Which planet has a ring system?
Jupiter Uranus Neptune Saturn
Jovian planets;
Jupiter, Saturn, Uranus, and Neptune.
Name of temperature scale that places 0 at a point where all atomic and molecular motion ceases?
Kelvin
The___ ___ extends about beyond the orbit to about 2 times the distance of Neptune from the sun
Kuiper Belt
What are two advantages of large scopes over smaller ones?
LARGE TELESCOPE CAN COLLECT MORE LIGHT AND HAS BETTER RESOLUTION
You could more easily resolve a close double star with a blue filter than with a red one.
True
this design combines the radiation from two diffeent telescopes to greatly enhance resolution cia computer syntheiss
interferometer
The twin 10-m Keck telescopes can work together to obtain better angular resolution through a technique known as __________.
interferometry
When an atom loses an electron, it becomes
ionized
Neptune
is about 30 times as far from the Sun as our planet
Jupiter
is the jovian planet that orbits closest to the sun
Venus
is the planet with the highest average surface temperature
one advantage of the hubble space telescope over ground based ones is that
it can bettr focus X-ray images
Grass (that is healthy) looks green because
it reflects green light and absorbs other colors.
what is the resolution of a telescope
its ability to distinguish two adjacent objects close together in the sky
a major advantage of newtonian reflector over a refractor is
its compact size
A major advantage of Newtonian reflector over a refractor is
its compact size.
Uranus
jas a rotational axis that is tilted so much it lies nearly in the plane of its orbit
The main reason that most professional research telescopes are reflectors is that
large mirrors are easier to build than large lenses.
what are two advantages of large scopes over small ones
large telescopes have more light grasp and better resolution
A 10-meter telescope has a larger __________-_________ _____ than a 4-meter telescope.
light-collecting area
How many atoms fit across the period at the end of this sentence?
millions
Compared to terrestrial planets, jovian planets are __________.
more massive and lower in average density
Click "show" for the emission line spectrum, then click "choose gases" and study the emission line spectrum for neon. The neon "OPEN" sign appears reddish-orange because __________.
neon atoms emit many more yellow and red photons than blue and violet photons
which design has a convex primary mirror and a flat seconadary mirror, with the eyepiece located on the top side of the telescope tube
newtonian reflector
Radio telescopes would not represent a good choice for astronomical study of which of the following types of object?
ordinary stars
which method od astornomical measurement is the precise measurment of brigthness
photometry
The ____ focus reflector needs only a single optical surface to form images.
prime
The Arecibo radio telescope is laid out like which optical telescope design?
prime focus reflector
Which type of telescope has the simplest light path?
prime focus reflector
the Arecibo radio telescope is laid out like whic optical telescope design
prime focus reflector
this design involves only one optical surface , a concave mirror
prime focus reflector
what type of telescope is the SUBARU
prime focus reflector
which type of telescope has the simplest light path
prime focus reflector
green light has a shorter wavelength than orange lit, in a 5 inch telescope green light will
provide better angular resolution than orange light
Green light has a shorter wavelength than orange light. In a 5 inch telescope, green light will
provide better angular resolution than orange light.
In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?
radio
which of the following is a problem inherent in all large radio telescopes
radio waves have long wavelentghs so radio telescopes have poor rsolution
Compared to optical telescopes, radio telescopes are built large because
radio waves have very long wavelengths
Rank the forms of light from left to right in order of increasing energy. To rank items as equivalent, overlap them.
radio waves, infrared, visible light, ultraviolet, x-rays, gamma rays
Rank the forms of light from left to right in order of increasing frequency. To rank items as equivalent, overlap them.
radio waves, infrared, visible light, ultraviolet, x-rays, gamma rays
From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
radio, infrared, visible light, ultraviolet, X rays, gamma rays
If telescope mirrors could be made of odd sizes, the one with the most light-gathering power would be
rectangle with two 1- sides and two 2- sides.
The primary reason professional observatories are built on the highest mountaintops is to
reduce atmospheric blurring
We can see each other in the classroom right now because we
reflect visible light.
the process occuringwhen photons bounce off a polished surface is called
reflection
Galileo's telescope designs using lenses were examples of _________ ________.
refracting telescopes
The twinkling of starlight and the focusing of images by lenses are both due to ____ of light.
refraction
the tendency of a wave to bend as it passes from one transparent medium to another is called
refraction
which design is subject to chromatic aberration
refractor
The ability of a telescope to separate two closely spaced stars is called _____.
resolution
it is diffraction that limits the ____ of a telescope of a given objective diameter
resolution
it is diffraction that limits the _____ of a telescopes objective
resolution
Compared with radio telescopes, optical telescopes can
resolve finer detail
which of these devices helps correct coma in fast reflectors
schmidt corrector plate
The light-gathering power of a telescope varies with the ____ of the diameter of the lens or the mirror.
size
Which of the following best describes Pluto in terms of the general characteristics of terrestrial and jovian planets?
size and solid surface similar to terrestrial planets; distance similar to jovian planets
The image shown in Figure 5.10 in the textbook ("Resolution") is sharpest when the ratio of wavelength to telescope size is
small
Terrestrial Planets
solid, rocky surface, located within the inner solar system, small size
the name of the new infrared orbiting obervatory is the
spitzer space telescope
diffraction is the tendency if light to...
spread around corners
Astronomical observations at these wavelengths can be obtained even during ______.
storms
Which of the following studies is best suited to a timing experiment?
studying whether a particular star's brightness is steady or variable
During the time that a comet passes through the inner solar system, the comet can appear quite bright because____?
sunlight reflects off the comet's tail and coma
what is the resolving power of a telescope
the ability to distinguish adjacent objects in the sky
When multiple radio telescopes are used for interferometry, resolving power is most improved by increasing
the distance between telescopes
The wavelength of a wave is
the distance between two adjacent peaks of the wave.
what problem is adaptive optics designed to correct
the effects of atmosphereic turbulence
the long period of comets are believed to come from
the oort cloud
Which of the following could not be determined by an observation that uses only spectroscopy?
the size of a distant galaxy
the amount of diffraction on a telescope creates depends upon
the wavelength and the diameter f the telescope objective
the amount of diffraction and thus the resolution of the scope depends upon
the wavelength used and the size of the main telescope objective lens or mirror
The amount of diffraction and thus the resolution of the telescope depends upon
the wavelength used and the size of the main telescope objective lens or mirror.
what is true of rario telecopes
they ahve poorer angular resolution than a reflector
The most important advantage of CCDs over film is that
they record much more light in a given exposure time.
the most important advantage of ccd over film is that
they record much more light ina given exposure time
compared to optical telescopes, radios telescopes are built larger becase
theyre less expensive to make than optical telescopes
Which of the following is not a good reason to place observatories on remote mountain tops?
to be able to observe at radio wavelengths
what is the primary purpose of an astornomical telescope
to collect alot of light and bring it into a focus
What is the purpose of adaptive optics?
to eliminate the distorting effects of atmospheric turbulence for telescopes on the ground
What problem does adaptive optics correct?
turbulence in the Earth's atmosphere that creates twinkling
what problem does adaptive optics correct
turbulence in the erath's atmosphere which creates twinkling
which of the follwoing gratly improves the angular resolution of radio maps
use of interferometer
If the ____ is good, the atmosphere is stable, and image quality is sharp.
visibility
Which of the following forms of light can be observed with telescopes at sea level?
visible light, radio waves
in which part of the electromagentic spectrum have astronomers unable to get any information
we now can cces information in all speccrtal lines
Produced by hot high density light source
Continuous spectrum
What is the resolution of a telescope?
Its ability to distinguish two adjacent objects close together in the sky.
A Newtonian reflector needs no secondary mirror.
False
A convex lens is thinnest in its center; it refracts light to a focus, while a convex mirror reflects it to the focus instead.
False
A telescope with and 8-inch mirror will collect twice as much light as one with a 4-inch mirror.
False
Absorption of light passing through the glass is a bigger problem for Cassegrain reflectors than achromatic refractors.
False
All modern large optical telescopes are refractors.
False
Chromatic aberration affects reflector telescopes.
False
Galaxies look the same whether viewed in visible or X-ray wavelengths.
False
Galileo is credited with designing the first reflector telescope.
False
Gamma-ray telescopes employ the same basic design that optical instruments use.
False
Hubble Space Telescope is still the largest scope ever built.
False
In the future, adaptive optics will greatly enhance the resolution of the Hubble Space Telescope.
False
Like radio and optical astronomy, infrared astronomy is easily done with ground-based telescopes.
False
Optical interferometry is more in use than radio interferometry.
False
Photography with film is still the preferred way of capturing fine detail in the faintest, most distant galaxies.
False
Radio astronomy can only be done from up in space, due to our ionosphere.
False
The Compton GRO was the first telescope used for our exploration of high-energy astronomy.
False
The Earth's atmosphere is the major factor limiting the use of ground-based radio telescopes.
False
The Hubble Space Telescope gives us its best resolution with X-rays.
False
The Keck telescopes contain the largest single mirrors ever constructed.
False
The main advantage to using the HST is the increased amount of "night time" viewing it affords.
False
The mirrors for X-ray telescopes are same shape as those of optical reflectors.
False
The primary purpose of any telescope is to produce an enormously magnified image of the field of view.
False
The simplest scope design, by Isaac Newton, uses only a primary mirror.
False
The term seeing is used to describe how faint an object can be detected by a telescope.
False
primary purpose of an astronomical telescope is to magnify the images of distant objects, making them appear closer.
False
It is impossible to overcome the atmospheric blurring experienced by ground-based optical telescopes. T/F
False. Active and/or adaptive optics can be used to compensate for much of the distortion of light due to atmospheric turbulence.
CCD cameras and photographic film have roughly the same efficiency for collecting light. T/F
False. Although CCD cameras have replaced photogenic film in most applications, film is still used or some specialized applications.
Advantage of the Hubble Telescope over ground
It reduces atmospheric blurring
As a rotating gas cloud contracts...?
It spins faster
Which light can be observed with telescopes at sea level?
Radio and Visible
Chromatic Aberration in lenses is a result of which wave property of light?
Refraction
Radio telescopes have poorer angulation over a...?
Refractor the same mass
A telescope that uses a lens and no mirrors is a..?
Refrator
It is diffraction that limits the ____ of a telescope of a given objective diameter.
Resolution
Jovian planets have..?
Rings around their equators
The name of new Infrared Orbiting Observatory
SPITZER SPACE TELESCOPE
Diffraction is the tendency of light to:
SPREAD AROUND CORNERS
A change in amplitude is a change in.?
Saturation
What are the names of the Jovian planets
Saturn, Jupiter, Uranus, Neptune
Waves can be transferred though...?
Solid, liquid, gas, and a magnetic feild
_____________ separate the various colors of light, allowing astronomers to determine stellar composition and may other stellar properties.
Spectrographs
As a solar nebula contracts it...?
Spins faster due to conservation of angular motion
Why do stars appear to twinkle? What do astronomers use to overcome this twinkle?
Stars appear to twinkle because of the instability of the Earth's atmosphere; astronomers use adaptive optics to overcome this effect.
Astronomical observations at these wavelengths can be obtained during__________
Storms
The amount of diffraction a telescope creates depends upon:
THE WAVELENGTH AND THE DIAMETER OF THE TELESCOPE OBJECTIVE
The most important advantage of CCDs over film is that
THEY RECORD MUCH MORE LIGHT IN A GIVEN EXPOSURE TIME
What is the primary purpose of an astronomical telescope?
TO COLLECT A LOT OF LIGHT AND BRING IT INTO FOCUS
What problem does adaptive optics correct?
TURBULENCE IN THE EARTH'S ATMOSPHERE WHICH CREATES TWINKLING
Which of the following statements best describes the two principal advantages of telescopes over eyes?
Telescopes can collect far more light with far better angular resolution.
These are all properties of what type of planets? -high density -closeness to the sun -rocky terrain
Terrestial
A telescope design that uses a lens and no mirrors is a refractor.
True
All optical telescopes will bring the light from a star to a focus.
True
All radio telescopes are reflectors in design.
True
An object having a temperature of 300 would be best observed with an infrared telescope.
True
As a rule, larger telescopes can detect fainter objects.
True
CCD detectors gather light 0 - 20 times faster than most sensitive photographic film.
True
Due to our ozone layer, ultraviolet astronomy must be done from space.
True
In addition to visible light, Hubble can do some work in the infrared and ultraviolet portions of the spectrum.
True
Mt. Palomar's 200" Gale telescope is the largest reflector now in service.
True
One reason for building telescopes on mountain tops is that they improve seeing by reducing the amount of air above the observer.
True
Optical telescopes are usually used only at night, but radio telescopes can be used day or night.
True
Radio telescopes are large in part to improve their angular resolution, which is poor because of the long wavelengths at which they are used to observe the skies.
True
Radio telescopes have poorer angular resolution than optical telescopes because radio waves a much longer wavelength than optical waves.
True
Radio telescopes have poorer angular resolution than optical telescopes because radio waves have a much longer wavelength than optical waves.
True
Stars do not twinkle; the instability of the atmosphere causes this effect.
True
The 400" Keck reflector can see objects 100 times fainter than the 40" Yerkes lens.
True
The Cassegrain reflector needs a primary concave main mirror and a smaller, convex secondary mirror to reflect light back through a hole in the primary.
True
The Schmidt corrector plate largely cures spherical aberration, giving a wide, flat field of view.
True
The light-gathering ability of a telescope is most dependent on the diameter of its primary objective.
True
The opacity of the atmosphere is partially corrected via adaptive optics.
True
The simplest reflector telescope design is the prime focus reflector.
True
What is image processing?
Computer processing of electronic images to correct for defects and remove noise
In design, most radio telescopes, like Arecibo, are ____.
...
0 degrees K lies at
0 Kelvin
Based on the frequency with which we see comets from Earth, astronomers estimate the total number of comets in the solar system to be
1 trillion
a mountain top is an esentially good site for infrared telescopes since
1)closer to celestial objects 2)less air means better seeing 3)cold wwather helps sensitivity of infrared detectors 4)above most carbod dioxide and vapor water
why are most large telescopes reflectors, not refractors
1)large mirros need 1 surface, achromats need 4 surfaces 2)reflectors do not suffer from chromatic aberration 3)large lenses are harder to cast as oppose to mirrors 4) large lenses deform under their own weight, mirror can be suposrted
The large reflector, the 10m Keck, gathers ____ times more light than the 1.0 m Yerkes refractor.
100
a telescope with a 60 mm objective lens collects how many times as much light as doe syour eys 6 mm exit pupil
10x
How much more light would a 2-m-diameter telescope gather in a certain amount of time at a given wavelength compared with one that is 50 cm in diameter?
16 times
An atom of the element iron has an atomic number of 26 and an atomic weight of 56. If it is neutral, how many protons, neutrons, and electrons does it have?
26 protons, 30 neutrons, 26 electrons
Speed of light
300,000 km/s
The angular resolution of an 8inch telescope is _____ times greater than a 2inch telescope
4
What is the light gathering power of an 8 inch telescope compared to a 4 inch telescope
4 times better
What is the light-gathering power of an 8 inch telescope compared to a 4 inch telescope?
4 times better
Approximate age of the solar system
4.6 billion years old
the angular resolution of an 8 inch diameter telescope is ____ greater than that of a 2 inch diameter telescope
4x
what is the light-gathering power of an 8 inch telescope compared to a 4-inch telescope
4x better
The trojan asteroids are found
60 degrees infront of or behind jupiter
The # if electrons determines whether..
An atom carries a charge as an ion or is neutral
What is a CCD, and how does it work? Why is it replacing film?
A CCD is a charge coupled device. It consists of a grid of thousands of light-sensitive pixels that build up a digital image that can be stored on computer as light strikes it, and it can also be sent over a computer network. CCDs are more sensitive to faint light than film.
What is "seeing"?
A MEASUREMENT OF THE IMAGE QUALITY DUE TO AIR STABILITY
A meteoRITE is..?
A chunk of space debris that has stuck in the ground
As a comet rounds the sun what does it leave?
A cometary dust tail behind, Bluish ionish
The nucleus of a comet is typically
A few km in size and a very low density
Most astronomers now believe the demise of dinosaurs 65 million years ago was caused by...?
A large Asteroid impacting the yucatan penisula
What is the asteroid belt?
A large groupd of asteroids w/ orbits located between mars and jupiter
A newtonian reflector needs..?
A secondary mirror
The oort cloud is believed to be
A spherical cloud of cometary nuclei far beyond the kuiper belt
A meteor is..?
A streak of light in the atmosphere
What is the source of material of a meteror shower
Comets
Produced by a hot, high density light source shinning through a cool, low-density medium
Absorption Spectrum
What kind of spectrum does the sun have?
Absorption spectrum
Rapid modifications are made to tilt and the location of the element of a telescope to correct the effects of atmospheric and instrumental distortion
Active Optics
What do all of these have in common? -comet nuclei -Polar caps of mars -kuiper belt objects -most jovian satellites
All icy composition
All terrestial planets lie within the...?
Asteroid belt
These distinguish _____ -compositions similar to that of the terrestial planets - typically orbit the sun @ appx 3 AU
Asteroids
Which objects are composed of material mostly unchanged since the formation of the solar system?
Asteroids and Comets
How do asteroids differ from comets?
Asteroids are rocky bodies and are denser than the comets, which are made of icy material.
At the wavelengths, it is to build telescopes with very large light collection _____ to obtain sufficient detail
Baselines
Anything that perfectly absorbs or radiates waves of all wavelengths
Black Body
In ____ Model of the atom, an electron can only exist in specific, well defined energy levels
Bohr
The dwarf planet Eris was discovered in 2005, orbiting the Sun at an average distance about twice that of Pluto. In which of the following ways do Pluto and Eris differ from the terrestrial and jovian planets in our solar system?
Both Pluto and Eris are smaller than any of the terrestrial planets.Both Pluto and Eris travel in more elliptical orbits than any of the terrestrial or jovian planets. Both Pluto and Eris are less massive than any of the terrestrial or jovian planets.
To a large degree, the ____ has replaced photographic film for astronomical imaging.
CCD
Which of the following is a principal advantage of CCDs over photographic film?
CCDs capture a much higher percentage of the incoming photons than does film.
These gather light 10-20 times faster than the most sensitive photography film
CDC detector
Which of the following is currently supplying high resolution x-ray images from space?
CHANDRA
What problem do refractor telescopes have that reflects don't?
CHROMATIC ABERRATION
What type of telescope focus is behind a central hole in the main mirror?
Cassegrain
The largest asteroid and probably the only one to be spherical "world" is..?
Ceres
Which of the following is currently supplying high resolution X-ray images from space?
Chandra
Type of Distortion in which there is a failure of lens to focus all colors to the same convergence point
Chromatic Aberration
Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestial planets?
Closer together and jovian would be further apart
A change in frequency is a change in....
Color
A _____ consists of dust nd gas released from a comet as it is heated by the sun
Coma
The bight spherical part of a coma observed when it is close to the sun is the_____
Coma
These distinguish a _________ -form a coma when near sun -most located either in kuiper belt or oort cloud -visible in the sky as a fuzzy patch of liht that rises and sets with the stars
Comet
This has an icy composition
Comet
The Spitzer Space Telescope (SST) is stationed far from Earth because
Earth is a heat source and the telescope must be kept very cool.
What is the main reason that ultraviolet astronomy must be done in space?
Earth's atmosphere absorbs most ultraviolet wavelengths
What is the main reason ultraviolet astronomy must be done from space?
Earth's atmosphere absorbs most ultraviolet wavelengths.
An _____ _____ results from an electron falling from higher to lower energy orbital around its nucleus
Emission lines
The spectral lines of each element are distinctive to that element whether we are looking at...
Emission lines or absorption lines
Produced by hot, low density source
Emission spectrum
The shorter the wavelength, the greater its______
Energy
In non-ionized hydrogen for instance, what does a higher orbital state have more of than a lower orbital state?
Energy.
A comet entering the inner solar system from afar will..?
Enter coma and later on form a tail
Many observatories are placed on top of mountains so they will be closer to the objects they are observing. T/F
False. An observatory on a tall mountain is above much of the atmosphere. Atmospheric effects are a primary reason why Earth-based telescopes cannot achieve their diffraction-limited resolution.
Reflecting telescopes usually suffer from chromatic aberration. T/F
False. Chromatic aberration is associated with refracting telescopes
Gamma-Ray telescopes are hard to make because they require large lenses or mirrors for focusing in order to make images. T/F
False. Gamma-ray telescopes work by absorbing high-energy photons, not by reflecting or refracting them.
The primary purpose of a telescope is to provide a magnified image of the stars. T/F
False. Magnification is secondary. Almost all stars appear as only points of light through even the most powerful telescopes. Light-gathering power and resolving power are the most important properties of astronomical telescopes.
One challenge in building large radio telescopes is getting the large surfaces smooth enough to act as mirrors. T/F
False. Since radio waves have fairly long wavelengths, centimeters to meters, the reflector surfaces do not have to be extremely smooth.
The Hubble Space Telescope is the largest optical telescope ever built. T/F
False. The HST owes its image quality (after correction for an error in the primary mirror) to the lack of atmospheric blurring.
A telescope with a 2-m diameter primary mirror would be more affected by diffraction than one with a 1-m-diameter mirror. T/F
False. The diffraction limit on resolution would actually be better (smaller) for the larger telescope.
An optical telescope of a given size would have better resolution in orange light than in blue light. T/F
False. The diffraction limit to resolution would be larger, producing worse resolution, in orange light than in blue light for a given telescope.
Terrestial planets have how many moons?
Few to none
Most energetic photon
Gamma-rays
The element 1st found in the sun's spectrum, then in earth's 30 years later is..?
Helium
The ____ Space telescope still gives us the highest resolution optical images.
Hubble
In astronomy, an interferometer can be used to
IMPROVE THE ANGULAR RESOLUTION OF RADIO TELESCOPES
Radio dishes are large in order to:
INCREASE THEIR ANGULAR RESOLUTION AND COLLECT THE VERY WEAK RADIO PHOTONS
These two photos were taken at the same time and same location near San Jose, California. The one on the left was taken using visible light. Considering the properties of the other parts of the electromagnetic spectrum, which type of radiation do you think was able to penetrate the dust and smog to obtain the image on the right?
INFRARED
What is the resolution of a telescope?
ITS ABILITY TO DISTINGUISH TWO ADJACENT OBJECTS CLOSER TOGETHER IN THE SKY
How do radio interferometers greatly enhance resolution in radio wavelengths?
In interferometry, two or more radio telescopes are used to observe the same exact object at the same time and at the same exact wavelength. This greatly enhances the resolution in radio wavelengths.
Primary advantage of techniques of radio interfermotry is..?
Increase in resolving power
Radio astronomers have pioneered use of multiple telescopes working in concept that can produce maps of radio emssions as detailed as optical images. These arrays of multiple telescopes are known as____?
Inferometers
Tessterial planets
Inner planets: Mars, mercury, earth, and Venus
How does the Sun's mass compare with that of the planets?
It is a thousand times more massive than all the planets combined.
Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?
It is closer to the stars.
What do we mean by the diffraction limit of a telescope?
It is the best angular resolution the telescope could achieve with perfect optical quality and in the absence of atmospheric distortion.
If we double the diameter of a telescopes mirror, what happens to the light gathering ability?
It quadruples
Which of the following is NOT a reason to use a reflecting telescope rather than a refractor?
Lenses are harder to focus than mirrors
The orbit of most comets
Lie almost entirely beyond the orbit of neptune
Objects in the kuiper belt.....?
Lie beyond neptune and close to the ecliptic
Large mirrors have larger..?
Light Collection
Which planet, other than Earth, has visible water ice on it?
Mars
Properties in a star cannot provide the...
Mass
The most metal-rich terrestrial planet is
Mercury
Order of planets closet to farthest from sun
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
These distinguish_____ -visible in the sky as bright streak of light only a sew seconds -Dust particles entering earth's atmosphere @high speed
Meteor
Particles ejected from a comet can cause a ____ ____ on earth
Meteor shower
Barringer Carter in Arizona is an example of..?
Meteorite impact
Mercury and Venus do not have..?
Moons
In general the spectral lines of molecules are..?
More complex than those of atoms
Compared to terrestial planets Jovian planets are____
More massive and less dense
Observations at wavelengths other than optical and radio need to be conducted by what telescopes
Most absorptions at wavelengths other than optical and for radio need to be conducted by space based telescopes
Earth
Most of the surface of ___ is covered with liquid water.
Which of the following statements is not an observed pattern of motion in our solar system?
Most planets orbit at the same speed.
What are meteorites made out of?
Mostly Rock
Do all planets orbit the sun in the same plane as earth?
NOOOO
Pluto is one of the largest of1000 of kuiper bodies found beyond..?
Neptune
Optical telescopes are used during...? And Radio are used during..??
Night Day
A comet's_______ is the frozen portion of it
Nucleus
Jovian Planets
Numerous orbiting moons, extensive ring systems, low average density, primarily composed of hydrogen helium and hydrogen compounds
What type of planet is this? -accreted from planestesmal of rock and metal -surfaces dramatically altered during the heavy bombardment
Terrestial
A comet's plasma tail always points directly away from the sun because...?
Of pressure exerted by the fast-moving charges particles in solar wind
The most distant objects in our solar system are..?
Oort Cloud
About a trillion comets are thought to be located far, far beyond pluto in the....?
Oort cloud
These are properties that suggest long-period comets originate from ____ _____ -orbits highly elliptical -orbital period is 200+ years -many have large inclination relative to the ecliptic plane
Oort cloud
What type of single telescope currently in operation has the highest angular resolution?
Optical
The Hubble telescope provides the best resolution for...?
Optical and ultraviolet wavelength
Radio telescopes would not represent a good choice for astronomical study for______?
Ordinary Stars
Which method of astronomical measurement is the precise measurement of brightness?
PHOTOMETRY
This design involves only one optical surface, a concave mirror. What is it?
PRIME FOCUS REFLECTOR
Which type of telescope has the simplest light path?
PRIME FOCUS REFLECTOR
Moving through space the vibrating electrical and magnetic fields of a light wave must move _______ to each other
Perpendicular
These two photos show the same region of space. One of them is taken in visible light. Note that stars are obscured in Photo 2 but are much easier to see in Photo 1. Considering the properties of the different bands of the electromagnetic spectrum, which spectral region do you think was used to take each photo?
Photo 1 is infrared; Photo 2 is visible
Why do astronomers need different telescope designs to observe across the electromagnetic spectrum?
Photons of different energy behave differently and require different collection strategies.
The orbit is almost circular with low eccentircities
Planetary orbit
Which of the following is not a pattern of motion in our solar system?
Planets all rotate in the same direction.
A comet's ____ ____ stretches away from the sun
Plasmic tail
The broader the spectral lines the higher the _______ of the gas creating it
Pressure
Green light has a shorter wavelength than orange light. In a 5 inch telescope green will...?
Provide more angular resolution than orange light
Compared to optical telescopes, radio telescopes are built large because
RADIO PHOTONS DON'T CARRY MUCH ENERGY
Which of the following is the problem inherent in all large radio telescopes?
RADIO WAVES HAVE LONG WAVELENGTHS,SO RADIO TELESCOPES HAVE POOR RESOLUTION
The process occurring when photons bounce off a polished surface is called:
REFLECTION
The tendency of a wave to bend as it passes from one transparent to another is called
REFRACTION
Large arrays of widely separated radio telescopes can achieve very good resolution. What is the primary reason that such good resolutions cannot be achieved by individual radio telescopes operating independently
Radio dishes larger than a few tens of meters across are difficult to build, limiting their individual resolutions to several times worse than the largest optical mirrors.
What are some advantages of radio telescopes over optical telescopes?
Radio telescopes can be used during the day and on cloudy nights. They are also not affected by atmospheric distortion.
Radio telescopes have poorer angular resolution than optical telescopes because..?
Radio wavelengths are larger than optical waves
Rank the forms of light from left to right in order of increasing speed. To rank items as equivalent, overlap them.
Rank the forms of light from left to right in order of increasing speed. To rank items as equivalent, overlap them. (all the same)
What is meant in astronomy by the phrase "active optics"?
Rapid modifications are made to the tilt and location of the elements of a telescope to correct for the effects of atmospheric and instrumental distortion.
A star cooler than the sun would appear...
Red
Listed following are distinguishing characteristics and examples of reflecting and refracting telescopes. Match these to the appropriate category.
Reflecting Telescopes: most commonly used by professional astronomers today, The Hubble Space Telescope, world's largest telescope Refracting Telescopes: The world's largest is 1-meter in diameter, Galileo's telescopes, very large telescopes become "top- heavy", incoming light passes through glass
The large research observatories on Mauna Kea use giant ________ __________.
Reflecting telescopes
A telescope becomes larger and larger, astronomers favor_____
Reflecting telescopes because large lenses and mirrors sag under their own weight and it's easier to support a mirror along its entire back side than it is to support a lens only around the edge
As telescopes become larger and larger, astronomers favor
Reflecting telescopes, in part because large lenses and mirrors sag under their own weight, and it is easier to support a mirror along its entire back side than it is to support a lens only around its edge
Reasons to use a reflecting telescope over a refractor
Reflecting the lens doesnt sink Lens must have 2 precision surfaces a mirror only needs one Lenses=Chromatic aberration Lenses absorb light
Discuss several advantages of reflector over refractor telescopes.
Reflectors are less expensive than refractors of similar size. Reflectors are free of chromatic aberration. The eyepiece position on a reflector is generally better place on a reflector. Reflectors can also be made much larger than refractors.
Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestrial planets?
Terrestrial planets will likely be located nearer the planetary system's star than any jovian planets.
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic weight?
The atomic number is 79, and the atomic weight is 197.
What is meant by the "diffraction limited resolution" of a telescope?
The best possible angular resolution that can be obtained by a telescope of a given size if all other sources of blurring are eliminated
The reflector needs a concave main mirror and a similar, convex mirror to reflect light back through a hole in the primary
The cassegrain
Iron meterorites are believed to come from
The core of differentiates asteroids now broken up.
The use of infrared telescopes includes..?
The detector and telescope must be cooled to a very low temperature
Which of the following statements about the use of infrared telescopes is true?
The detector and telescope must be cooled to very low temperatures.
The light gathering ability of a telescope is most dependent on the...?
The diameter of its primary objective
Relative to the comet the direction of the ion tail tells us..?
The direction of the sun
An x-ray telescope in Antarctica would not work well because
The earths atmosphere
Astronomers use the term "seeing" to describe which of the following?
The effects of atmospheric turbulence
When an electron goes from higher energy level down to a ground state, how does the light emit?
The electron absorbed moves up to the higher level **Electromagnetic radiation
Which of the following statements about light focusing is not true?
The focal plane of a reflecting telescope is always located within a few inches of the primary mirror.
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. If it is doubly ionized, what is the charge of the gold ion and how many electrons remain in the ion?
The gold ion has a charge of +2 and 77 electrons.
Stars dont twinkle because...?
The instability of the atmosphere
The definition of density is...?
The mass per unit of volume
The thickest lenses deflect and bend light
The most
Mars
The only rocky planet to have more than one moon
Mercury
The planet that orbits closet to the sun
Saturn
The planet with the lowest average density
What is meant by the "prime focus" of a telescope?
The point at which the incoming light is focused to produce an image, where analysis instruments and imaging cameras can be placed
The arecibo radio telescope is laid out like this optical design
The prime focus Reflector
The product of the light collecting arc and the exposure time that determines...
The total amount of light collected from a distant object
We can learn a lot about the properties of a star by studying its spectrum. All of the following statements are true except one. Which one?
The total amount of light in the spectrum tells us the star's radius.
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.
The # of protons identifies..?
The type of element
The amount of diffraction and the resolution of the telescope depends upon...?
The wavelength used and the size of the main telescope objective lens or mirror
Which of the following observations indicates that conditions on Mars may have been suitable for life in the past?
There are dried-up riverbeds on Mars.
Which of the following is an advantage the Hubble Space Telescope has over ground-based telescopes?
There is no blurring due to the atmosphere
Explain three advantages the Hubble Space Telescope has over all ground-based telescopes.
There is no interference of the Earth's atmosphere. It is able to capture clearer images. It can capture more light from distant objects than ground-based telescopes.
Which of the following is not a characteristic of the inner planets?
They all have substantial atmospheres.
Which of the following is always true about images captured with X-ray telescopes?
They are always displayed in false color.
Name two advantages of larger telescopes over smaller ones.
They have a greater collecting area, and they have a finer angular resolution.
What is true of radio telescopes?
They have poorer angular resolution than a refractor of the same size.
Which of the following is not a characteristic of the outer planets?
They have very few, if any, satellites.
The most important advantage over CCD's over time is
They record much more light in a given exposure time
What happens to the absorption and/or emission spectrum lines of an object moving away from earth@ high Speed?
They will be shifted toward the red end of the spectrum
The primary reason professional observatories are built on the highest mountains is..?
To reduce atmospheric blurring
Radio waves can penetrate dusty regions of interstellar space because they are relatively unaffected by this intervening matter. T/F
True. Many parts of interstellar space (including the center of our Galaxy) cannot be seen at optical wavelengths, but are easily detectable in the radio region.
Both the Keck and VLT observatories are designed to permit interferometry to be used. T/F
True. Although the technique of interferometry was pioneered using radio telescopes, it is now being extended to the infrared, and perhaps eventually optical regions. See Section 5.6 in your textbook.
Radio telescopes often position their detectors at prime focus. T/F
True. Section 5.5 of the text and the online image archive for Chapter 5 contain many pictures showing such arrangements.
Ultraviolet and X-ray telescopes can be used only above Earth's atmosphere. T/F
True. The atmosphere is opaque to electromagnetic radiation higher in frequency (i.e., shorter in wavelength) than the near ultraviolet, so UV and X-ray astronomy must be conducted from space. Gamma rays, however, can be observed from the ground—not directly, but by observing the results of their interactions with the atmosphere.
The biggest telescopes in use today are reflectors, not refractors. T/F
True. The largest telescopes in all wavelength regions from radio to X-rays are all reflectors.
Cassegrain-style telescopes are characterized by a hole in the objective mirror. T/F
True. The resulting folded optical path is used in many commercial amateur and professional telescope designs.
The amount of light collected by a telescope is proportional to its area. T/F
True. This is the reason that astronomers need larger telescopes to study fainter objects.
Radio observations may be made in the daytime as well as at night. T/F
True. Yes. Although the Sun is a radio source, it does not interfere unduly with daytime use of radio telescopes.
Radio telescopes using very long baseline interferometry have produced images with resolutions similar to those of images produced with optical telescopes. T/F
True. As far as resolving power is concerned, the effective diameter of an interferometer is the distance between its outermost dishes.
One scheme for improving telescopic images involves collecting data from a part of the sky where there are no known sources of radiation. T/F
True. The data collected would consist of background noise. This data can be used in computer processing of images taken with the telescope to improve the quality of the image.
Which planet is approximately halfway between pluto and the sun?
Uranus
Which planet is approximately halfway between Pluto's orbit and the Sun?
Uranus, the seventh planet from the Sun
The planet closest in size to Earth is
Venus
Which planet has the highest average surface temperature, and why?
Venus, because of its dense carbon dioxide atmosphere
The shortest wavelength (color)
Violet
Surface zone light observations
Visible (optics) and radio
Electromagnetic radiation penetrates the atmosphere of earth at what portions of the electromagnetic spectrum
Visible, some Infarared and some radio
In which part of the electromagnetic spectrum have astronomers been unable to get any information?
WE NOW CAN ACCESS INFORMATION AT ALL SPECTRAL LENGTHS
the shortest electromagnetic wavelength?
X-ray
Grazing incidence optics are critical to focusing ____.
X-rays.
A mountain top is an especially good site for infrared telescopes since:
YOU ARE ABOVE MOST OF THE CARBON DIOXIDE AND WATER VAPOR IN THE ATMOSPHERE
The radiation our eyes are most sensitive to is the color..?
Yellow-green at 550 nm
A hydrogen atom consists of an electron and a a. proton b. neutron c. neutrino d. lepton
a
One of the research objectives of the ATLAS experiment at the LHC is a. to determine what happened in the first few seconds after the Big Bang b. to help us to understand what exactly happened during the creation of the earth c. to create a gigantic black hole d. all of the above sponsor
a
Please refer to page 6. The constellation labeled as "2" is called A. Ursa Major B. UrsaMinor C. Orion D. Lyra
a
Please refer to page 6. The constellation labeled as "5" is called A. Andromeda B. Orion C. Cassiopea D. Lyra
a
Please refer to page 6. The point B on the sketch of an ellipse is called A. Perihelion B. Aphelion C. Eccentricity D. Node
a
The Large Hadron Collider, just completed in Geneva, is getting ready to collide two beams of protons at energy of 14 TeV. The word "hadron" refers to a. protons and similar particles b. electrons and similar particles c. a company which has contracted the LHC d. a name of the major sponsor
a
Tycho Brahe's contribution to Kepler's Laws of Planetary Motion were A. his detailed and accurate observations of the planet's position B. his observations of Jupiter's moons C. a mathematical explanation of epicycles D. a precise lunar calendar
a
What is the name of the effect when an electromagnetic wave is bent as it passes from one material into another? a. refraction b. reflection c. deflection d. diffraction
a
Which of the following statements about light is FALSE? a. The speed of light is lower for radio than for X-rays. b. Nothing moves faster than light. c. The speed of light is equal to 3·108 m/s. d. The speed of light is equal to three hundred thousand kilometres per second.
a
Why are molecular lines more complex than elemental spectral lines? A. Molecules can vibrate and rotate as well B. Molecules are heavier than atoms C. Molecules are the basis of life D. Most of the universe is made of molecules, not individual atoms
a
what is "seeing"
a measurement of the image quality due to air stability
What is a compound?
a molecule containing two or more elements
What is an artificial star?
a point of light in Earth's atmosphere created by a laser for the purpose of monitoring atmospheric fluctuations
Study the graph of the intensity of light versus wavelength for continuous spectra, observing how it changes with the temperature of the light bulb. Recall that one of the laws of thermal radiation states that a higher-temperature object emits photons with higher average energy (Wien's law). This law is illustrated by the fact that for a higher temperature object, the graph peaks at __________.
a shorter wavelength
All optical telescopes will bring the light from
a star to focus
Estimate the angular resolution of the 8.1 m Gemini North telescope in red light. A. 0.10' B. 0.02" C. 0.10" D. 0.20"
b
When used in a single instrument to greatly enhance its resolution, the four separate mirrors of the VLT act as a(n) _____.
interferometer
____ optics deform the shape of the mirror to compensate for the turbulence in the atmosphere and yield a close to diffraction-limited range.
adaptive
____ optics greatly reduces the effect of atmospheric turbulence by deforming the shape of the mirror by computer control.
adaptive
What type of visible light spectrum does the Sun produce?
an absorption line spectrum
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 light reflects off an object, what is the relation between the angle of incidence and the angle of reflection?
angle of incidence = angle of reflection
How long, approximately, would a radar signal take to complete a round-trip between Earth and Mars when the two planets are 1.3 AU apart? A. 650 seconds B. 1300 seconds C. 43 minutes D. 87 minutes
b
If a light source is approaching you at a speed very close to the speed of light, it will appear a. redder than it is b. bluer than it is c. brighter than it is d. fainter than it is
b
In order from low to high frequency, which of the following lists is correct? a. gamma-rays, X-rays, ultraviolet, visible, infrared, microwave, radio b. radio, microwave, infrared, visible, ultraviolet, X-rays, gamma-rays c. gamma-rays, X-rays, ultraviolet, visible, infrared, radio, microwave d. radio, microwave, ultraviolet, visible, infrared, X-rays, gamma-rays
b
Please refer to page 6. The brightest star in constellation "3" is called A. Vega B. Polaris C. Alpheratz D. Betelgeuse
b
Please refer to page 6. The constellation labeled as "3" is called A. Ursa Major B. UrsaMinor C. Orion D. Andromeda
b
The Orion Nebula, M-42, is a hot, thin cloud of glowing gas, so its spectrum is: A. a continuum, strongest in the color red. B. a few bright lines against a dark background C. a few dark line in the continuum. D. not in the visible portion of the spectrum.
b
What are constellations? a. Groups of galaxies gravitationally bound and close together in the sky b. Groups of stars making an apparent pattern in the celestial sphere c. Groups of stars gravitationally bound and appearing close together in the sky d. Ancient story boards, useless to modern astronomers
b
The absorption line spectrum shows what we see when we look at a hot light source (such as a star or light bulb) directly behind a cooler cloud of gas. Suppose instead that we are looking at the gas cloud but the light source is off to the side instead of directly behind it. In that case, the spectrum would __________.
be an emission spectrum
compared to a 5 inch prime focus reflector a 5 inch newtonian refractor will
be easier to build
What causes stars to twinkle?
bending of light rays by turbulent layers in the atmosphere
Where are most of the known asteroids found?
between the orbits of Mars and Jupiter
The kuiper belt is found where in the solar system?
beyond the orbit of neptune
Please refer to page 6. The constellation labeled as "4" is called A. Andromeda B. Orion C. Cassiopea D. Lyra
c
The orbital period of the asteroid Ceres is 4.7 Earth years. What is its semi-major axis? A. 8.8 × 106 m B. 2.209 × 108 km C. 4.2 × 108 km D. 13.4 × 104 AU
c
The wavelength of the red hydrogen line is A. 364.8 nm B. 486.1nm C. 656.3 nm D. 1.36 × 105 angstroms
c
There are no x-ray telescopes on Earth because A. they are too expensive to build B. no one has yet invented an x-ray telescope that works C. x-rays don't penetrate Earth's atmosphere D. there are no astronomical objects that emit x-rays
c
Which of the following are the jovian planets? a. Jupiter, Saturn, Uranus, Neptune, and Pluto. b. Jupiter only. c. Jupiter, Saturn, Uranus, and Neptune. d. Mars, Jupiter, Saturn, Uranus, and Neptune
c
A mirror must be ____ in shape to focus the transmitted light.
concave
A lens must be _____ in shape to focus the transmitted light.
convex
what type of telescope is the hubble space telescope
cassegrain
the convex secondary mirror in this deisgn focuses light down a hole cut in the concave primary mirror
cassegrain reflector
which of the following is currently supplying high resolution x-ray images from space
chandra
The separation of red and blue light in a single-lens telescopes is called ____ aberration.
chromatic
What problem do refractor telescopes have that reflectors don't?
chromatic aberration
refractor telescopes suffer from this separation of light into its component colors
chromatic aberration
what ptoblem do refractor telescope have that reflectors dont
chromatic aberration
Adding a secondary concave lens of carefully chosen different glass to the primary lens on a refractor allows
chromatic aberration to be reduced.
An advantage a reflector has over a refractor is the elimination of _____.
chromatic aberration.
The primary purpose of a telescope is to
collect a large amount of light and bring it into focus.
the primary purpose of a telescope is to
collect a large amount of light and bring it to a focus
16. According to Wein's Law, if the Sun's surface temperature of 5800 K were doubled: A. the Sun would look much redder than it does now. B. the Sun would now radiate four times more total energy into space. C. most of the Sun's radiation would be in the form of the heat, not light. D. the peak of its energy would now fall in the ultraviolet part of the spectrum.
d
According to Kepler's third law, the square of the planet's period in years is a. equal to its perihelion distance from the Sun in A.U b. inversely proportional to its mass in kilograms c. equal to the fourth power of its average temperature in degrees Kelvins d. proportional to the cube of its semimajor axis in A.U
d
At which of these Kelvin temperatures would a blackbody radiate mostly at visible wavelengths: A. 6 K B. 60 K C. 600 K D. 6000 K
d
Increasing the temperature of a blackbody by a factor of 3 will increase its energy by a factor of A. 3 B. 9 C. 12 D. 81
d
Please see page 6. The aphelion distance of Mars from the Sun is approximately A. 0.31 AU B. 0.47 AU C. 1.38 AU D. 1.67 AU
d
What causes seasonal variations on Earth? A. wobble of Earth's rotation axis B. global warming and cooling C. variations in distance of Earth from the Sun D. tilt of the Earth's rotational axis with respect to its orbital axis
d
What is "seeing"? A. a measure of the quality of the telescope's optics B. a measure of the transparency of the scope's objective lens C. a measurement of the sharpness of vision of the astronomer's eyes D. a measurement of the image quality due to air stability
d
Which of the choices below correctly lists things in order from largest to smallest? a. Local Group, Solar System, Milky Way, Universe b. Local Group, Milky Way, Solar System, Universe c. Universe, Milky Way, Local Group, Solar System d. Universe, Local Group, Milky Way, Solar System
d
Which of these bodies is misplaced? a. Mercury = 0.4 AU b. Venus = 0.72 AU c. Earth = 1.0 AU d. Jupiter = 12.5 AU
d
If our eyes were sensitive only to X rays, the world would appear __________.
dark because X-ray light does not reach Earth's surface
Telescopes operating at this wavelength must be cooled to observe faint astronomical objects.
extreme infrared
Order the following in order of increasing efficiency of detecting photons of visible light.
eye, photographic film, CCD
The angular resolution of an 8 inch diameter telescope is ____ times greater than that of a 2 inch diameter telescope.
four
We divide the electromagnetic spectrum into six major categories of light, listed below. Rank these forms of light from left to right in order of increasing wavelength. To rank items as equivalent, overlap them.
gamma rays, x-rays, ultraviolet, visible light, infrared, radio waves
Using ____ incidence optics, the Chandra is the X-ray equivalent of the Hubble Space Telescope.
grazing
The Chandra X-Ray observatory focuses X rays with _________ _________ mirrors.
grazing incidence
the design of moder x-ray telescopes depends on
grazing incidence optics
The design of modern X-ray telescopes depends on
grazing incidence optics.
the chandra x-ray telescope must use
grazingincidence optics to focus the short wavelentghs
Process of accretion
growth of an object by the accumulation of matter
Compared to a 5 inch prime focus reflector, a 5 inch Newtonian reflector will
have the same light gathering power
Which of the following objects is not a close approximation of a thermal emitter?
hot, thin air
What are the main constituents of the jovian planets?
hydrogen and helium
in astronomy an interferometer can be sued to
improve the angular resolution of radio telescopes
In astronomy, an interferometer can be used to
improve the angular resolution of radio telescopes.
Where does nuclear fusion occur in the Sun?
in its core
One advantage of the Hubble Space telescope over ground based ones is that
in orbit, it can operate close to its diffraction limit at visible wavelengths.
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
radio dishes are large in order to
increase their angular resolution and collect the very weak radio photons
In general, as a telescope's diameter increases, its angular resolution _____.
increases
The best way to study young stars hidden behind interstellar dust clouds would be to use
infrared light
