ASTR 1161 ch 6

If you wanted a radio telescope to achieve the same angular resolution as a visible-light telescope, it would need to be:

much larger

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

to be able to observe at radio wavelengths

Interferometry uses two or more telescopes to achieve:

an angular resolution equivalent to that of a much larger telescope

How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope?

4X

Improvements in technology will eventually allow the entire electromagnetic spectrum to be observed from high mountaintop observatories. T/F

False

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.

What do astronomers mean by light pollution?

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

Suppose that two stars are separated in the sky by 0.1 arcsecond. If you look at them with a telescope that has an angular resolution of 0.5 arcsecond, what will you see?

One point of light that is the blurred image of both stars.

What does angular resolution measure?

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

The lens in your eye forms an upside-down image of the world. T/F

True

Which technology can allow a single ground-based telescope to achieve images as sharp as those from the Hubble Space Telescope?

adaptive optics

Which of the following effects is caused by atmospheric turbulence? a. light pollution b. twinkling of stars c. diffraction of light d. magnification of images

b. twinkling of stars

If you see the color red in an X-ray image from the Chandra X-Ray Observatory, it means:

it depends: the colors are chosen arbitrarily to represent something about the X rays recorded by the telescope.

Suppose you want to determine the chemical composition of a distant planet or star. What would be useful to have?

High spectral resolution.

Which of the following is always true about images captured with X-ray telescopes? a. They are always shown with colors that are NOT the true colors of the objects that were photographed. b. They show us light with extremely long wavelengths compared to the wavelengths of visible light. c. They always have very high angular resolution. d. 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.

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

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

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

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

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

d. A refracting telescope uses a transparent glass lens to focus light while a reflecting telescope uses a mirror to focus light.

Where should you put a telescope designed for ultraviolet observations?

in earth orbit

The twinkling of stars is caused by:

motion of air in our atmosphere