AST 112 - HW 5

Currently the largest optical telescope mirrors have a diameter of

10 m

Suppose astronomers build a 120 m telescope. How much greater would its like collecting area be than that of the 10 m Keck telescope

140

The Hubble space telescope obtains higher-resolution images than most ground based telescopes because it is

Above earth atmosphere

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

Adaptive optics

The diffraction limit is a limit on

A telescope's angular resolution

What is an artificial star

A point of light in earth's atmosphere created by a laser for the purpose of monitoring atmospheric fluctuations

What causes stars to twinkle

Bending of light rays by turbulent layers in the atmosphere

Telescopes operating at this wavelength must be cooled to observe faint astronomical objects

Extreme infrared

The Hubble space telescope is famous because at least at the time of its launch it was the largest visible light telescope ever built

False

True or false —— a radio telescope and an optical telescope of the same size have the same angular resolution

False

True or false ——professional astronomical telescopes generally have a much greater magnification than the telescopes you can buy in stores

False

True or false: X-ray telescope mirrors are very similar to optical telescope mirrors

False

True or false—— a larger telescope will always have a higher spectral resolution than a smaller telescope when observing at the same wavelength

False

True or false——Improvements in technology will eventually allow the entire electromagnetic spectrum to be observed from high mountaintop observatories

False

How much greater is the light collecting area of one of the 10 m keck telescopes than that of the 5 m Hale telescopes

Four

How much greater is the light collecting area of a 6 m telescope than a 3 m telescope

Four times

What do astronomers mean by light pollution

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

What does the technique of interferometry allow

It allows two or more telescopes to obtain the angular resolution of a single telescope much larger than any of the individual telescopes

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

What is meant by spectral resolution

It is a measure of how close two spectral lines can be distinguished

What following statement is not an advantage of the Hubble space telescope over ground-based telescopes

It is closer to the stars

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

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

Much larger

Why do astronomers need different telescope designs to observe across the electromagnetic spectrum

Photons of different energy have different wavelengths, some of which are not accessible from earth's surface and require different collection strategies

At which wavelength range is there no current or planned space observatory

Radio

In what part of the electromagnetic spectrum do the biggest telescopes on earth operate

Radio

What following studies is best suited to a time monitoring experiment

Studying whether a particular star's brightness is steady or variable

What statement best describes the two principal advantages of telescopes over eyes

Telescopes can collect far more light with far better angular resolution

What is not true about light focusing

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

What statement could not be measured by an observation that uses only imaging

The rate at which a variable star brightens and dims

What following statement cannot be determined by an observation that uses only spectroscopy

The size of a distant galaxy

Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes

The two stars will look like a single point of light

What following statement is always true about images captured with X-ray telescopes

They are always displayed in false color

What is the purpose of adaptive optics

To eliminate the distorting affects of atmospheric turbulence for telescopes on the ground

True or False——X-rays from astronomical objects can only be detected from telescopes in space

True

True or false ——most astronomical objects emit light over a broad range of wavelengths

True

True or false ——the angular resolution of a telescope is never less than its diffraction limit

True

True or false ——the lens in your eye forms and upside-down image of the world

True

True or false——process of science: if any single test of a scientific hypothesis contradicts it, the hypothesis must be revised

True

What wavelength regions cannot be studied with telescopes on the ground

Ultraviolet and x-rays