chapter 6 astronomy

Which type of focus is most common for larger telescopes?

Cassegrain focus

Why aren't optical or radio telescopes used in particle astronomy, which studies cosmic waves and gravity waves?

Optical and radio telescopes can only detect electromagnetic radiation.

​What must be used to maintain the optics and operation of an infrared telescope?

coolant

Space-based telescopes carrying long-wavelength infrared detectors must carry coolant such as liquid helium to chill their optics to near absolute zero temperature.

true

​Which form of radiation has the lowest frequency?

microwave

​The larger the diameter of a telescope, the more light it will collect.

True

​What is the function of the receiver antenna of a radio telescope?

To absorb the radio energy collected by the dish

What is so unique about the mirrors of telescopes such as the Keck Observatory, Gran Telescopio Canaries, and the soon-to-be-built Giant Magellan Telescope?

The mirrors are segmented

What type of electromagnetic radiation does Chandra collect?

X-ray

Light-gathering power and resolving power both depend on what characteristic of a telescope?

diameter

​Where would you most likely find a large radio telescope?

in a mountain valley

​The Very Large Array radio telescope in New Mexico is an example of the use of which astronomical technique?

interferometry

​Refracting and reflecting telescopes form an image that is small, inverted, and difficult to observe directly; therefore, an eyepiece is normally used to magnify the image and make it convenient to view.

True

​Reflecting telescopes suffer from chromatic aberration because the light must pass through the glass.

false

​Which type of electromagnetic wave is the shortest?

gamma

​Which telescope will be launched into solar orbit and eventually replace observations made by the Hubble Space Telescope?

JWST

What is the shape of the segmented mirrors of twin Keck Observatory telescopes, Gran Telescopio Canarias, and the James Webb Space Telescope (scheduled to be launched in late 2018)?

hexagonal

​All telescopes must be operated on site by an astronomer or a technician.

false

n the above image (Figure 6-1), what part of the telescope is represented by the pointer?

achromatic lense

​Which part of a telescope is responsible for magnifying an image?

eyepiece

Jenny, who lives on a farm in a rural part of New York, calls her cousin, Karen, in Brooklyn, to tell her that she can see the Milky Way in tonight's night sky. However, Karen says she can't see it at all.  What is preventing Karen from seeing the Milky Way in the night sky?

Karen lives in an area with light pollution

​Radio telescopes are often located near populated areas.

false

A(n) __________ is both an image-recording device and a photometer.

CCD

​What characteristic of a telescope controls the amount of light captured by the telescope?

diameter of the tube

Diffraction, optical quality, and atmospheric conditions all contribute to the limitations of what power of a telescope?

resolving power

​What does a refracting telescope use to gather and focus light?

lens

​Refracting telescopes use a mirror to gather and focus light.

false

The energy a photon carries is inversely proportional to __________.

its wavelength

​Which form of electromagnetic radiation is able to easily reach Earth's surface through an atmospheric window?

radio

​If telescope A is 160 cm in diameter, and telescope B is 32 cm in diameter, how much more light does telescope A gather than telescope B?

25 times

​The ____ of a radio telescope collects and focuses radiation.

dish

No radio waves penetrate the Earth's atmosphere.

false

​A spectrograph spreads out light according to ____ to form a spectrum.

wavelength

​What telescope instrument is used to counter the eastward rotation of Earth?

sidereal drive

gravity waves have never been detected

false

​What unit is used to measure wavelengths?

nanometer

Which power of a telescope reveals fine details within an image?

resolving power

​CCD images captured from telescopes are often ____ to be stored in a computer's memory for later analysis.

converted to numerical data

Visible light with wavelengths at the long-wavelength end (λ = 700 nm) appears as which color?

red

​What technique often requires the use of a laser guide star?

adaptive optics

​Resolving power is measured in nanometers.

false

What modern-day instrument do astronomers use to record images from telescopes?

charge-coupled device

​What does chromatic aberration separate within refracting telescopes?

color

​What is a major selecting factor for astronomers looking to place a telescope atop a mountain?

non-turbulent airflow

Cosmic rays are made of photons.​

false

​Which is the longest surviving, and most successful, space telescope?

Hubble space telescope

​Short-focal-length lenses and mirrors must be strongly curved.

true

​Why are X-rays and gamma rays considered dangerous forms of light?

photons of these wavelengths have high energy

​Red light of the visible light spectrum has longer wavelengths than blue.

true

​Which telescope is the largest refracting telescope in the world?

\n ​Yerkes Observatory refractor telescope