Untitled Flashcards Set

Question 1:In astronomy, an interferometer can be used to:

Answer: improve the angular resolution of radio telescopes.

Question 2: Which type of telescope has the simplest light path?

Answer: single lens refractor

Question 3: The angular size of an object depends on which two quantities?

Answer: the object's actual size and its distance from us

Question 4: Which design has a concave primary mirror and flat secondary mirror, with the eyepiece located

Answer: Newtonian reflector

Question 5: Stefan's Law says:

Answer: that if the Sun's temperature were doubled, it would give off 16X more energy.

Question 6: The temperature scale that places zero at the point where all atomic and molecular motion ceases is

Answer:Kelvin

Question 7: According to Wein's Law, if the surface temperature is increased by a factor of 2, its peak wavelength will:

Answer: decrease by a factor of 2.

Question 8: The process occurring when photons bounce off a polished surface is called

Answer:reflection

Question 9:Very hot, young stars, like those in Messier 2 emit most of their light in which part of the electromagnetic spectrum?

Answer: the ultraviolet

Question 10: the resolvable angle for a telescope will become smaller if

Answer: the wavelength of the incoming light gets shorter or its aperture gets bigger.

Question 11: An astronomer discovers a new star and wants to measure its temperature. She would do this by

Answer: making a blackbody curve and finding the wavelength of the peak (maximum).

Question 12: The tendency of a wave to bend as it passes from one transparent medium to another is called:

Answer: refraction

Question 13: If a material is transparent, then it

Answer: transmits light well.

Question 14:  If a material is highly opaque, then it

Answer: absorbs most light.

Question 15: The Earth's ionosphere partially blocks which form of electromagnetic radiation?Answer:radio

Question 16:Diffraction is the tendency of light to

Answer: spread around corners.

Question 17:  What is "seeing"?

Answer:a measurement of the image quality due to air stability

Question 18: Which form of electromagnetic radiation is absorbed by carbon dioxide and water vapor in our 18) atmosphere?

Answer: infrared

Question 19: What is the resolution of a telescope?

Answer: its ability to distinguish two adjacent objects close together in the sky

Question 20: Of all the forms of electromagnetic radiation, the one with the lowest frequency is:

Answer: radio waves

Question 21:The two forms of electromagnetic radiation that penetrate the atmosphere best are:

Answer: visible and radio waves.

Question 22: Consider this diagram. Which statement is true?

Answer: The wavelength is 6.

Question 23: The best way to study young stars hidden behind interstellar dust clouds would be to use

Answer: infrared light

Question 24: The largest refracting telescope in the world, financed by a Chicago millionaire in the 1890's is at the:

Answer: Yerkes Observatory

Question 25:  The Spitzer Space Telescope is stationed far from Earth because

Answer: Earth is a heat source and the telescope must be kept very cool.

Question 26: The Arecibo radio telescope is laid out like which optical telescope design?

Answer: prime focus reflector

Question 27: The name of the Infrared Orbiting Observatory launched in 2003 is the:

Answer: Spitzer Space Telescope

Question 28: Which form of electromagnetic radiation would be blocked in the stratosphere by ozone?

Answer: ultraviolet

Question 29: X-ray telescopes are located in orbit around the Earth becaus

Answer: X-rays don't reach the surface of Earth.

Question 30: What is the resolving power of the telescope?

Answer: the ability to distinguish adjacent objects in the sky

Question 31: We can see each other in the classroom right now because we

Answer: reflect visible light.

Question 32: Very low temperature molecular clouds emit most of their light in which part of the electromagnetic spectrum?

Answer: the radio

Question 33: The amount of diffraction, and thus the resolution of the telescope, depends upon

Answer: the wavelength used and the size of the main telescope objective lens or mirror.

Question 34: Which of these is constant for ALL types of electromagnetic radiation in a vacuum?

Answer: velocity

Question 35: It is diffraction that limits the ________ of a telescope of a given objective diameter.

Answer: resolution

Question 36: The most important advantage of CCDs over film is that:

Answer: they record much more light in a given exposure time.

Question 37: What problem does adaptive optics correct?

Answer: turbulence in the Earth's atmosphere which creates twinkling

Question 38: The first person (to the best of our knowledge) regularly to turn a telescope to astronomical observations was:

Answer: Galileo Galilei

Question 39: To avoid chromatic aberrations__________is used.

Answer: an achromatic lens

Question 40: Radio dishes are large in order to:

Answer: increase their angular resolution and collect the very weak radio photons.

Question 41: What type of telescope is the Hubble Space Telescope?

Answer:Cassegrain

Question 42: If a wave's frequency doubles, its wavelength:

Answer:is halved.

Question 43: Grass appears green because

Answer: it reflects green light and absorbs other colors.

Question 44: A mountain top is an especially good site for infrared telescopes since:

Answer: you are above most of the carbon dioxide and water vapor in the atmosphere.

Question 45: The convex secondary mirror in this design focuses light down through a hole cut in the concave primary mirror.

Answer:Cassegrain reflector

Question 46: A wave's velocity is the product of the:

Answer: frequency times the wavelength of the wave.

Question 47: The visible color of electromagnetic radiation that has the shortest wavelength is

Answer: violet

Question 48: Electromagnetic radiation:

Answer: can behave both as a wave and as a particle.

Question 49: To break up light into the component colors that it contains, astronomers use a device called

Answer: a spectrometer

Question 50: What is true of radio telescopes?

Answer: They have poorer angular resolution than a refractor.

Question 51: The angular resolution of an 10-inch diameter telescope is ________ greater than that of a 2-inch diameter telescope

Answer:16 times

Question 52: Everything looks red through a red filter because

Answer: the filter transmits red light and absorbs other colors.

Question 53: Stars like our Sun emit most of their light in which part of the electromagnetic spectrum

Answer:the visible

Question 54: To avoid spherical aberrations__________is used.

Answer: a parabolic mirror

Question 55: ________ optics deform the shape of the mirror to compensate for the turbulence in the atmosphere and yield a close to diffraction-limited image.

Answer: Adaptive

Question 56: The size of an image produced by a telescope is directly proportional to

Answer: the focal length of the collecting surface.

Question 57:  Adding a secondary concave lens of carefully chosen different glass to the primary lens on a refractor allows

Answer: chromatic aberration to be reduced.

Question 58: The hottest objects with temperatures in the millions of Kelvins, give off most of their radiation in which part of the electromagnetic spectrum?

Answer:gamma ray

Question 59: Blue light has a shorter wavelength than green light. In a 5-inch telescope, blue light will

Answer:provide better angular resolution than orange light.

Question 60: The SOFIA Project is:

Answer:an airplane with an infrared telescope on board, designed to fly above much of the water vapor in the Earth's atmosphere.

Question 61: At which of these Kelvin temperatures would a blackbody radiate mostly at visible wavelengths?

Answer: 6000 K

Question 62: The Sun's blackbody curve peaks in the ________ portion of the spectrum.

Answer: visible

Question 63: The detectors on the Spitzer Space Telescope were cooled to near absolute zero in order to:

Answer: prevent the infrared radiation from the instruments interfering with the infrared signals from space.

Question 64: What is true of a blackbody?

Answer:Its energy peaks at the wavelength determined by its temperature.

Question 65: onsider this diagram. Which statement is true?

Answer: The amplitude is 4.

Question 66: An idealized object that does not reflect or scatter any radiation, but simply absorbs every bit of radiation that falls on it is called:

Answer: a blackbody

Question 67: Suppose the angular separation of two stars is smaller than the angular resolution of your eyes.

Answer: the two stars will look like a single point of light.

Question 68: What is the primary purpose of an astronomical telescope?

Answer: to collect a lot of light and bring it to a focus

Question 69: The number of waves passing the observer per second is:

Answer: the frequency in Hertz.

Question 70: How are wavelength, frequency, and energy related for photons of light?

Answer:Longer wavelength means lower frequency and lower energy.

Question 71: Which of the following is currently supplying high resolution X-ray images from space?

Answer:Chandra

Question 72: Which method of astronomical measurement is the precise measurement of brightness?

Answer: photometry

Question 73: The radiation our eyes are most sensitive to is the color

Answer: yellow-green at about 550 nm.

Question 74: What is the light-gathering power of an 10-inch telescope compared to a 2-inch telescope?

Answer: 32× better

Question 75:What problem do refractor telescopes have that reflectors don't?

Answer: chromatic aberration