ASTR 152

Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light?

Getting an image of the same angular resolution requires a much larger telescope for radio waves than for visible light.

What is a CCD?

It is an electronic detector that can be used in place of photographic film for making images.

Which of the following is not an advantage of a telescope in space over ground-based telescopes?

It is closer to the stars.

Which of the following best describes the focal length of a telescope?

It is the distance from the lens or mirror to the image formed of a distant light source.

What is the purpose of adaptive optics?

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

The brightening of the night sky by light scattered from aritificial outdoor lighting is called

Light Pollution

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

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

What does resolving power measure?

The angular size of the smallest features that can be viewed with the telescope.

Suppose you have two small photographs of the Moon. Although both look the same at small size, when you blow them up to poster size one of them still looks sharp while the other one becomes fuzzy (grainy) looking. Which of the following statements is true?

The one that still looks sharp at large size has better (smaller) angular resolution than the one that looks fuzzy.

The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?

The photo will seem to show only one star rather than two.

The units of frequency are given in ____________.

cycles per second

Light is one form of ______ radiation.

electromagnetic

The number of wave cycles that pass in one second is called the _____ of the wave.

frequency

Light waves with a wavelength of 800 nm would be in which part of the electromagnetic spectrum?

infrared

The method of connecting multiple telescopes together to work as if they were a single telescope to obtain extremely high resolution images is called

interferometry

The ability of a telescope to collect light is called the

light-gathering power

Red light waves have ____ wavelength, ______ frequency, and travel at ______ speed compared to blue light waves when both are in space.

longer, lower, the same

The ability of a telescope to make an image appear larger is called the

magnifying power

Which power of a telescope is the least important?

magnifying power

A particle of light is called a

photon

The large lens or mirror that is used to focus the light in a telescope is referred to as the _____ lens or mirror.

primary

Which two forms of electromagnetic radiation are useful for observing the stars from the ground?

radio waves, visible

Telescopes which use a concave mirror to focus incoming light from the stars are called _____ telescopes.

reflecting

A ____ telescope uses a large lens to gather and collect light.

refracting

The distance between two successive peaks of a wave is called a

wavelength