! 3 ! Astronomy

Front 1

What is light?

Back 1

Light, more properly "visible light", is one form of electromagnetic radiation. All electromagnetic radiation (radio waves, infrared radiation, visible light, ultraviolet radiation, X rays, and gamma rays) has both wave and particle properties.

Front 2

What type of electromagnetic radiation is most dangerous to life?

Back 2

Gamma rays are most dangerous

UV light from sun is the most common though.

Front 3

What is the main purpose of a telescope?

Back 3

A telescope is designed primarily to collect as much light as possible.

Front 4

Why do stars twinkle?

Back 4

Rapid changes in density of the Earth's atmosphere cause passing starlight to change direction, making stars appear to twinkle.

Front 5

What type(s) of electromagnetic radiation can telescopes currently detect?

Back 5

Telescopes have been built tat can observe the entire electromagnetic spectrum.

Front 6

______, compact units of vibrating electric and magnetic fields, all carry energy through space at the same speed, "the speed of light" (300,000 km/s in a vaccuum, slower in any medium).

Back 6

Photons

Front 7

Radio waves, infrared radiation, visible light, ultraviolet radiation, X rays, and gamma rays are the forms of ____________ __________. They travel as photons, sometimes behaving as particles, sometimes as waves.

Back 7

electromagnetic radiation

Front 8

________ light occupies only a small portion of the electromagnetic spectrum.

Back 8

Visible

Front 9

The wavelength of a visible light photon is associated with its _______. Wavelengths of visible light range from about 400 nm for _______ light to 700 nm for _______ light.

Back 9

color
violet
red

Front 10

Infrared radiation and radio waves have wavelengths ______ than those of visible light. UV light, X rays, and gamma rays have wavelengths that are _______.

Back 10

longer
shorter

Front 11

The motion of an object toward or away from an observer causes the observer to see all the colors from the object to __________ or _________, respectively. This is generically called _________ shift.

Back 11

redshift
blueshift
doppler

Front 12

A telescope's most important function is to gather as much _______ as possible. Its second function is to reveal the observed object in as much detail as possible. Often the least important function of a telescope is to ________ objects.

Back 12

light
magnify

Front 13

_________ telescopes, or __________, produce images by reflecting light rays from concave mirrors to a focal point or focal plane.

Back 13

reflecting
reflectors

Front 14

_________ telescopes, or __________, produce images by benging light rays as they pass through glass lenses. Glass impurity, opacity to certain wavelengths, and structural difficulties make inadvisable to build extremely large refractors. __________ are not subject to many of the problems that limit the usefullness of refractors.

Back 14

Refracting
refractors
reflectors

Front 15

What are used to record images?

Back 15

Charged-coupled devices (CCD's)

Front 16

__________ telescopes are being built with active and adaptive optics. These advanced technologies yield resolving power comparable to the Hubble Space Telescope.

Back 16

Earth-based

Front 17

________ telescopes have large reflecting antennas (dishes) that are used to focus radio waves.

Back 17

Radio

Front 18

Very sharp radio images are produces with arrays of radio telescopes linked together in a technique called ____________.

Back 18

interferometry

Front 19

The Earth's atmosphere is fairly transparent to most visible light and radio waves, along with some infrared and UV radiation, arriving from space, but it absorbs much of the _______________ __________ at other wavelengths.

Back 19

electromagnetic radiation

Front 20

Explain some of the advantages of relecting telescopes over refracting telescopes.

Back 20

Refracting:
1. glass impurity
2. opacity to certain wavelengths
3. structural difficulties
4. can't build big ones

reflectors:
1. don't have those problems

Front 21

What are the three major function of the telescope?

Back 21

1. (most important) to gather as much light as possible.
2. reveal the observed object in as much detail as possible.
3. (least important) to magnify objects

Front 22

T or F

An light wave always has to travel through a medium.

Back 22

True

Front 23

Do we consider, for astronomy, a photon to be a wave or particle?

Back 23

wave

Front 24

What is angular resolution?

Back 24

It measures the clarity of the image

Front 25

Why must astronomers use satellites and Earth-orbiting observatories to study the heavens at X-ray wavelengths?

Back 25

Because they don't penetrate through the Earth's atmosphere because of the different gases in atmosphere.

Front 26

What are NASA's 4 great observatories and in what parts of the electromagnetic spectrum do they observe?

Back 26

Hubble Space Telescope -observes the Universe at ultraviolet, visual, and near-infrared wavelengths

Compton Gamma Ray Observatory - gamma ray

Chandra X-ray Observatory - X-ray

Spitzer Space Telescope - thermal infrared rays

Front 27

Why did Romer's observations of the eclipses of Jupiter's moons support of the heliocentric, but not the geocentric, cosmology?

Back 27

because when Jupiter and the Earth are in opposition, when they are on the same side as the sun, The Earth-Jupiter distance is relatively short compared to when Jupiter is near conjunction.