Astronomy 263 Chp 6 Purdue

T/F In the past, astronomers placed telescopes in highflying aircraft in an effort to rise above the water vapor in Earth's atmosphere.

TRUE

T/F Robotic spacecraft have visited most of the planets and moons of the solar system.

TRUE

the advantage of an interferometer is that a. the resolution is dramatically increased b. the focal length is dramatically increased c. the light-gathering power is dramatically increased d. diffraction effects are dramatically decreased e. chromatic aberration is dramatically decreased

ANSWER A THE RESOLUTION IS DRAMATICALLY INCREASED

Which of the following are used by astronomers to understand the universe? (select all that apply.) a. telescopes b. particle accelerators c. neutrino detectors d. supercomputers e. gravitational-wave detectors f. microscopes g. papers

ANSWER A, B, C, D, E, F, G TELESCOPES PARTICLE ACCELERATORS NEUTRINO DETECTORS SUPERCOMPUTERS GRAVITATIONAL-WAVE DETECTORS MICROSCOPES PAPERS

astronomers put telescopes in space to a. get closer to the stars b. avoid atmospheric effects c. look primarily at radio wavelengths d. improve quantum efficiency

ANSWER B AVOID ATMOSPHERIC EFFECTS

the angular resolution of a ground-based telescope is usually determined by a. diffraction b. the focal length c. refraction d. atmospheric seeing

ANSWER D

Improved resolution is helpful to astronomers because a. they often want to look in detail at small features of an object b. they often want to look at very distant objects c. they often want to look at many objects close together d. all of the above

ANSWER D ALL OF THE ABOVE

Refraction is caused by a. light bouncing off a surface b. light changing colors as it enters a new medium c. light speeding up as it enters a new medium d. light slowing down as it enters a new medium

ANSWER D LIGHT SLOWING DOWN AS IT ENTERS A NEW MEDIUM

robotic landers are more common than sample-return spacecraft because a. there is nothing to be learned by bringing back a bunch of rocks b. carrying enough fuel to get back to Earth makes sample return expensive c. the science instruments on landers are equal to any we have here on Earth d. we are nervous about cross-contamination of life forms

ANSWER D WE ARE NERVOUS ABOUT CROSS-CONTAMINATION OF LIFE FORMS

T/F Chromatic aberration is a problem that limits the image quality of REFLECTING telescopes.

Chromatic aberration is a problem that limits the image quality of REFRACTING telescopes but not REFLECTING telescopes. REFLECTING telescopes REFLECT light evenly and clearly while REFRACTING ones do not. FALSE

Which of the following can be observed from Earth's surface? a. radio waves b. gamma radiation c. far UV light d. x-ray light e. visible light

Earth's atmosphere blocks low energy radio waves, gamma radiation, far UV light and x-ray light? ANSWER E VISIBLE LIGHT

T/F One of the reasons why the Hubble Space Telescope has better spatial resolution than a 4-meter ground-based telescope is that is has a large mirror.

It has better spatial resolution because it is above Earth's atmosphere FALSE

The Kepler Mission telescope observes primarily in visible light. This telescope is located in space because a. visible light does not make it through Earth's atmosphere b. it is closer to the targets it is observing c. it is above atmospheric distortion d. it is safe from weather-related disasters

The Kepler Mission telescope is in space to overcome the atmospheric distortion. It is not there to stay safe from weather-related disasters. ANSWER C IT IS ABOVE THE ATMOSPHERIC DISTORTION

all large astronomical telescopes are reflectors because a. chromatic aberration is minimized b. they are not as heavy as refracting telescopes c. they can be shorter than refracting telescopes d. all of the above

a is true because... Chromatic aberration is minimized because large telescopes use mirrors instead of lenses. ANSWER D ALL OF THE ABOVE

Spacecraft are the most effective way to study planets in our solar system because a. planets move too fast across the sky for us to image them well from Earth b. planets cannot be imaged from Earth c. they can collect more information than is available just from images d. space missions are easier than long observing campaigns

a. is wrong because spacecrafts can indeed take pictures of moving planets, but spacecrafts are mainly used to collect info about planets b. is wrong because planets can be imaged by high resolution Earth based telescopes d. is wrong because space missions can be costly and harder than campaigns ANSWE C THEY CAN COLLECT MORE INFORMATION THAN IS AVAILABLE JUST FROM IMAGES

which of the following solar system objects has yet to be observed by flyby spacecraft? a. Uranus b. Venus c. Pluto d. Neptune

a. visited by Voyager 2 b. visited by Mariner2 in 1962 d. visited by Voyager 2 ANSWER C PLUTO

just remember this shet

aperture: diameter resolution: ability to distinguish close objects focal length: distance from lens to focal plane chromatic aberration: rainbow-making effect diffraction: smearing effect due to sharp edge interferometer: two or more telescopes connected to act as one adaptive optics: computer-controlled atmospheric distortion correction

T/F Radio telescopes are often used in interferometric arrays to increase light-gathering power.

interferometry array means multiple radio telescopes. By using large arrays, the light gathering power is not increased, but the angular resolution is improved. so therefore the statement is FALSE

the part of the human eye that acts as the detector is the a. retina b. pupil c. lens d. iris

pupil is a round bowl located in the center of the iris of the eye. Light travels through the pupil to reach retina. SO ANSWER A RETINA

a grating is able to spread white light out into a spectrum of colors because of the property of a. reflection b. refraction c. dispersion d. interference

reflection: light bouncing on a surface refraction: caused by light speeding up or slowing down as it enters a new medium dispersion: white light incident on a prism gets broken up into a spectrum of colors interference causes spectrum of colors in grating ANSWER D INTERFERENCE

Suppose that you are handed a telescope. The tube is roughly as long as your arm, but it is difficult to hold because you can barely get your arms around it. This (is the dumbest question ever) telescope is most likely a a. refractor b. reflector

refracting telescopes are small and thing telescopes used to collect light so therefore it is ANSWER B REFLECTOR

which causes the biggest problem in detecting infrared photons from an astronomical object? a. smog b. carbon dioxide c. water vapor d. light pollution

smog: doesn't absorb infrared photons carbon dioxide: not the biggest problem in detecting infrared photons light pollution: not a problem to detect infrared photons ANSWER C WATER VAPOR

You are shopping for telescopes online. You find two in your price range. One of these has aperture of 20 cm, and one has an aperture of 30 cm. Which should you choose, and why? a. the 20 cm, because the light-gathering power will be better b. the 20 cm, because the image size will be larger c.the 30 cm, because the light-gathering power will be better d. the 30 cm, because the image size will be larger

the larger the lens, the clearer the image will be ANSWER C THE 30 CM, BECAUSE THE LIGHT-GATHERING POWER WILL BE BETTER

the light gathering power of a 4-meter telescope is ______ than that of a 2-meter telescope a. 8 times larger b. 4 times larger c. 16 times smaller d. 2 times smaller

the light-gathering power of a telescope is proportional to the area of its aperture, therefore the light gathering power of 4 m telescope is 4 times larger than that of a 2 m telescope ANSWER B 4 TIMES LARGER