chapter 6

Currently, the largest optical telescope mirrors have a diameter of 2 m. 100 m. 10 m. 5 m. 1 m.

10 m

Where should you put a telescope designed for ultraviolet observations? in Earth orbit on an airplane on a high mountaintop

in Earth orbit

If you wanted a radio telescope to achieve the same angular resolution as a visible-light telescope, it would need to be: much larger. slightly larger. in space.

much larger

In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate? ultraviolet visible infrared X-ray radio

radio

Which of the following wavelength regions can be studied with telescopes on the ground? infrared, visible, and ultraviolet light. all light with wavelengths shorter than infrared wavelengths all light with wavelengths longer than ultraviolet wavelengths radio, visible, and very limited portions of the infrared and ultraviolet regions

radio, visible, and very limited portions of the infrared and ultraviolet regions

When your eye forms an image, the _____ plays a role analogous to the detector in a camera. lens pupil optic nerve retina

retina

Which of the following is not a good reason to place observatories on remote mountain tops? to reduce light distortion to be able to observe at infrared wavelengths to reduce light pollution to be able to observe at radio wavelengths to reduce light absorption

to be able to observe at radio wavelengths

The angular resolution of a telescope is never less than its diffraction limit. True False

true

The lens in your eye forms an upside-down image of the world. True False

true

Which of the following effects is caused by atmospheric turbulence? light pollution magnification of images twinkling of stars diffraction of light

twinkling of stars

Which of the following statements best describes the difference between a refracting telescope and a reflecting telescope? A refracting telescope uses a transparent glass lens to focus light, whereas a reflecting telescope uses a mirror to focus light. A refracting telescope produces refracted images, whereas a reflecting telescope produces reflected images. It is much easier to make a large refracting telescope than a large reflecting telescope. Reflecting telescopes make much clearer images than can refracting telescopes of the same size.

A refracting telescope uses a transparent glass lens to focus light, whereas a reflecting telescope uses a mirror to focus light.

Which of the following is a principal advantage of CCDs over photographic film? CCDs allow long exposures (e.g., minutes or hours), and film does not. CCDs can be attached to modern telescopes more easily than cameras. CCDs capture a much higher percentage of the incoming photons than does film. CCDs can record the colors of astronomical objects accurately, while film cannot. Images recorded with CCDs never require any image processing, while images recorded by film often do.

CCDs capture a much higher percentage of the incoming photons than does film.

Which of the following is not one of the three main categories of observation generally used by astronomers? Spectroscopy to spread an object's light into a spectrum. Time monitoring to track how an object's brightness varies with time. Imaging to get a picture of an astronomical objects. Filtering to look at just a single color from an object.

Filtering to look at just a single color from an object.

Suppose you want to determine the chemical composition of a distant planet or star. Which of the following will be most useful to have? A radio telescope. High angular resolution. High turbulence. High spectral resolution.

High spectral resolution.

What is the purpose of interferometry? It reduces the twinkling of stars caused by atmospheric turbulence. It allows two or more small telescopes to achieve the angular resolution of a much larger telescope. It allows two or more small telescopes to achieve a larger light-collecting area than they would have independently. It is designed to prevent light pollution from interfering with astronomical observations.

It allows two or more small telescopes to achieve the angular resolution of a much larger telescope.

What do we mean by the diffraction limit of a telescope? It is the angular resolution the telescope could achieve if nothing besides the size of its light-collecting area affected the quality of its images. It describes the farthest distance to which the telescope can see. It describes the maximum exposure time for images captured with the telescope. It is the maximum size to which any telescope can be built.

It is the angular resolution the telescope could achieve if nothing besides the size of its light-collecting area affected the quality of its images.

What do we mean by the diffraction limit of a telescope? It is the maximum size to which any telescope can be built. It is the best angular resolution the telescope could achieve with perfect optical quality and in the absence of atmospheric distortion. It describes the farthest distance to which the telescope can see. It describes the maximum exposure time for images captured with the telescope.

It is the best angular resolution the telescope could achieve with perfect optical quality and in the absence of atmospheric distortion.

Which of the following 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 (not blurry) image of an object viewed through the telescope. It is the lower surface of the telescope's primary lens or mirror. It is the surface of the lens on the eyepiece, through which you would look to see objects in the telescope's field of view. It is the upper surface of the telescope's primary lens or mirror.

It is the place where, if we mounted film or an electronic detector, we could get a clear (not blurry) image of an object viewed through the telescope.

What is the purpose of adaptive optics? It allows several small telescopes to work together like a single larger telescope. It is a special technology that allows the Hubble Space Telescope to adapt to study many different types of astronomical objects. It reduces blurring caused by atmospheric turbulence for telescopes on the ground. It allows ground-based telescopes to observe ultraviolet light that normally does not penetrate the atmosphere.

It reduces blurring caused by atmospheric turbulence for telescopes on the ground.

What do astronomers mean by light pollution? Light pollution is a term used to describe the appearance of the sky in regions that are crowded with stars. Light pollution is light from human sources that makes it difficult to see the stars at night. Light pollution means contamination of light caused by chemicals in the Earth's atmosphere. Light pollution is a type of air pollution created by lightweight gases such as hydrogen and helium.

Light pollution is light from human sources that makes it difficult to see the stars at night.

What do astronomers mean by light pollution? Light pollution is another name for sunlight, which makes it impossible to see stars in the daytime. Light pollution refers to the lights that must be used inside major observatories and that make it difficult for astronomers' eyes to adapt to darkness. Light pollution refers to light used for human activities that brightens the sky and hinders astronomical observations. Light pollution refers to pollution caused by light industry as opposed to heavy industry. Light pollution refers to harmful gases emitted by common street lights.

Light pollution refers to light used for human activities that brightens the sky and hinders astronomical observations.

Which of the following statements best describes the two principle advantages of telescopes over eyes? Telescopes can collect far more light with far better angular resolution. Telescopes can collect far more light with far greater magnification. Telescopes collect more light and are unaffected by twinkling. Telescopes have much more magnification and better angular resolution.

Telescopes can collect far more light with far better angular resolution.

What does angular resolution measure? The brightness of an image. The angular size of the smallest features that the telescope can see. The number of electromagnetic waves captured by an image. The size of an image.

The angular size of the smallest features that the telescope can see.

Which of the following statements about light focusing is not true? In a healthy eye, light is focused on the retina. The focal plane of a reflecting telescope is always located within a few inches of the primary mirror. Film should be placed at the focal plane in a camera. Light can be focused with a lens or a mirror. If you try to look at an image that is not formed at the focal plane, it will be blurry.

The focal plane of a reflecting telescope is always located within a few inches of the primary mirror.

Which of the following is always true about images captured with X-ray telescopes? They show us light with extremely long wavelengths compared to the wavelengths of visible light. They are always pretty. They always have high angular resolution. They are always shown with colors that are not the true colors of the objects that were photographed. They always are made with adaptive optics.

They are always shown with colors that are not the true colors of the objects that were photographed.

What is the angular resolution of the human eye? about 1 degree about 1 arcminute, or 1/60 of a degree about 1 arcsecond (1/3600 of a degree) about 1 milliarcsecond

about 1 arcminute, or 1/60 of a degree

The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is: larger. closer to the stars. above Earth's atmosphere.

above Earth's atmosphere.

What causes stars to twinkle? variations in the absorption of the atmosphere bending of light rays by turbulent layers in the atmosphere It is intrinsic to the stars-their brightness varies as they expand and contract. variable absorption by interstellar gas along the line of sight to the star the inability of the human eye to see faint objects

bending of light rays by turbulent layers in the atmosphere

Which of the following wavelength regions cannot be studied with telescopes on the ground? radio waves ultraviolet X rays both B and C both A and C

both B and C

The Hubble Space Telescope is famous because, at least at the time of its launch, it was the largest visible light telescope ever built. True False

false