Homework #6

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 collect and focus light while a reflecting telescope uses a mirror to collect and focus light.

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?

twinkling of stars

If your eyes were sensitive only to X-rays, the world would appear _______.

Dark, because X-ray light does not reach Earth's surface.

Suppose you want to determine the chemical composition of a distant planet or star. Which of the following will be most useful to have?

High spectral resolution

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

What is the purpose of adaptive optics?

It allows ground-based telescopes to observe UV light that normally does not penetrate the atmosphere.

What is the purpose of interferometry?

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

What do astronomers mean by "light pollution?"

It 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 0.19 arcsecond. If you look at them with a telescope that has an angular resolution of 0.4 arcsecond, what will you see?

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

Based on how your eye works and how it compares to a telescope, we can say that the _______ plays a role analogous to the mirror size in a telescope system.

Pupil

Which of the following statements best describes the two main advantages of telescopes over eyes?

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

What does 'angular resolution' measure?

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

Which of the following is always true about images captured with X-ray telescopes?

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