Exam 4: Telescopes: the Tools of Astronomy

Explain why the image seen in astronomical telescopes is inverted.

A lens must be _ in shape to focus the transmitted light.

The light- gathering power of a telescope varies with the of the diameter of the lens or mirror.

Galaxies look the same whether viewed in visible or X- ray wavelengths.

A mirror must be in shape to reflect the light back to a focus.

optics greatly reduces the effect of atmospheric turbulence by deforming the shape of the mirror by computer control.

If the _ is good, the atmosphere is stable, and image quality is sharp.

Why is the angular resolution of radio telescopes much worse than that of smaller optical telescopes?

optics deform the shape of the mirror to compensate for the turbulence in the atmosphere and yield a close to diffraction- limited image.

With a prime focus reflector, why is digital imaging much easier than using an eyepiece for visual work?

The ability of a telescope to separate two closely spaced stars is called _.

The mirrors for X- ray telescopes are the same shape as those of optical reflectors.

What is the light- gathering power of an 8- inch telescope compared to a 4- inch telescope?

Radio telescopes have poorer angular resolution than optical telescopes because radio waves have a much longer wavelength than optical waves.

What problem does adaptive optics correct?

The amount of diffraction and thus the resolution of the telescope depends upon

The opacity of the atmosphere is partially corrected via adaptive optics.

Green light has a shorter wavelength than orange light. In a 5- inch telescope, green light will

Why doesn't the Hubble Space Telescope need adaptive optics?

What problem do refractor telescopes have that reflectors don't?