Chapter 6

Question 1

We collect and measure what from astronomical sources
through the use of a what?

Answer 1

electromagnetic radiation, telescopes

Question 2

a telescope is a what collecting what of light as they what?

Answer 2

light bucket, photons, rain down

Question 3

The most important functions of a
telescope are (1) to collect the what from an astronomical source and (2) to focus all the light into a what or an what?

Answer 3

faint light, point, image

Question 4

Telescopes that collect visible radiation use a what or what to gather the light.

Answer 4

lens, mirror

Question 5

We can compare their light-gathering power by comparing the what, or what, of the opening through which light travels or reflects.

Answer 5

apertures (diameters)

Question 6

The light gathering power of a telescope is proportional to its what squared.

Answer 6

diameter

Question 7

optical telescopes-those designed to collect what.

Answer 7

visible light

Question 8

Telescopes can form images in one of two ways: using lenses
(what) or mirrors (what).

Answer 8

refracting, reflecting

Question 9

When light passes through a lens, the light beam bends (or what)
and gets focused at a point.

Answer 9

refracts

Question 10

A telescope that uses lenses to focus an image is called a what
telescope.

Answer 10

refracting

Question 11

when light passes through a lens, the different wavelengths
of light bend by different amounts, causing the image to be
blurred. This is known as what?

Answer 11

chromatic aberration

Question 12

which telescope is used more?

Answer 12

reflecting telescopes

Question 13

about how large can a reflecting telescope be built?

Answer 13

40 m in diameter

Question 14

The best observatory sites are on what, far from the what and
what of cities?

Answer 14

mountains, lights, pollution

Question 15

what poses a challenge for clear viewing of a telescope?

Answer 15

earths atmosphere

Question 16

Even on a clear night, the atmosphere filters out a certain amount of starlight, especially in the what, where the absorption is due primarily to what. Astronomers therefore prefer what, generally found at what altitudes?

Answer 16

infrared, water vapor, dry sites, high

Question 17

Observatories are best located at least how many miles from the nearest large city.

Answer 17

100 miles

Question 18

what refers to the precision of detail present in an image: that is, the smallest features that can
be distinguished.

Answer 18

resolution

Question 19

One factor that determines how good the resolution will be is the what of the telescope.

Answer 19

size

Question 20

The resolution of an image is measured in units of what on the sky, typically in units of what.

Answer 20

angle, arc seconds

Question 21

One arc second is what degree, and there are 360 degrees in a full circle

Answer 21

1/3600 degree

Question 22

Many astronomical objects emit what

Answer 22

radio waves

Question 23

the quality of resolution depends upon the what of the what that the telescope is gathering.

Answer 23

wavelength, radiation

Question 24

the what the wave is, the harder it is to obtain fine detail

Answer 24

longer

Question 25

To overcome this difficulty, radio astronomers have learned to sharpen their images by linking two or more radio telescopes together electronically. Two or more telescopes linked together in this way are called an
what

Answer 25

interferometer

Question 26

what is a technical term for the way that multiple waves interact with each other when they arrive
in our instruments, and this interaction allows us to coax more detail out of our observations.

Answer 26

interference

Question 27

Astronomers can link several telescopes together into an what.

Answer 27

interferometer array

Question 28

Radio telescopes can also perform what

Answer 28

radar imaging

Question 29

With infrared observations, astronomers can detect what parts of cosmic objects, such as the dust
clouds around star nurseries and the remnants of dying stars, that visible-light images don’t reveal.

Answer 29

cooler

Question 30

the what was the most successful space telescope

Answer 30

the Hubble telescope (2.4 m)

Question 31

when was the Hubble space telescope launched

Answer 31

1990

Question 32

what telescope is next to the Hubble in success?

Answer 32

James webb telescope (6 m)