astronomy exam 2

wave Propeties

particles hit something some, of it;s energy transfred to whatever is it

Limits for telescopes

Blurring

Field of View

Twinkling

wavelength

how LONG the wave is

frequency

how many times the wave WIGGLES

what do waves carry

a traveling disturbance caring energy

sound waves

requires a MEDIUM for wave to travel through

light waves

it can travel through a vacuum NO MEDIUM required

kinds of electromagnetic (light) waves (in order - by frequency or by wavelength)

radio waves

microwaves

infrared

visible

ultraviolet

X-rays
Gamma rays

What they tell us (why do we use spectra?)

The Elements present – which wavelengths absorbed/emitted

Temperature

And Velocity toward/away from us - Doppler effect

Energies of electromagnetic (light) waves - which are MORE energetic?

blue light

Energies of electromagnetic (light) waves - which are LESS energetic

red light

spectra: continuous spectrum

made by hot solid, liquid, or dense gas

spectra: Emission

made by an exited low-density gas and BRIGHT lines tell us about the element present

the 3 powers of a telescope

1) Light-gathering power

2) Resolving power

3) Magnifying power

spectra: Absorption 

a continuous source shining through a cooler, low density gas, that DARK lines tell us about the energy present

How spectra are formed - what is happening inside an atom to make it emit light?

electron eats photons (light energy ) to gain light 

Doppler Effect

if a moving source emits waves SQISHED when close to you

and or STRETCH when source is away from you

Windows” in the Earth’s atmosphere - what kinds of light can we observe from the ground?

Radio waves and visible light

ReFRECATORS - what do they use to bend light?

glass 

disadvantages of refractors

•Grinding both surfaces of lens is quite expensive

•Hard to make very large lenses

•Chromatic aberration – to many colors of light bend differently through the lens

ReFLECTORS - what do they use to bend light?

mirror

Why use a reflector rather than a refractor?

•Only one surface to grind

•Coat with reflective material – no chromatic aberration

•Can support mirror across back (less chance of warping)