Wavelength: distance from peak to peak (measured in nm)

Longest wavelength to shortest: red, orange, yellow, green, blue and violet

 -shorter the wavelength, the more the light is refacted

 Long wave lengths: little energy

 Short wavelength: lots of energy

 Light travels at finite speed and takes longer to travel farther distances 

 -Light waves of all wavelengths travel at the same speed through a vacuum (space)

 Radio waves, microwaves, infrared, visible light, ultra violet, x-ray, gamma rays

number of peaks to pass a certain point

Greater the frequency the shorter the wave length will be

Large frequency: short wavelength (ultraviolet etc. )

Small frequency: long wavelength (radio waves)

Blueshift –if each successive wave is emitted from a position slightly closer to viewer (rather than being stationary), see shorter wavelength and you will see blue regardless of distance (and vise versa if the object is moving away from you)-redshiftDoppler shift both are also called a

Doppler shift varies directly with approaching or receding speed—faster moving objects has color red/blue shifted twice as much as a slower moving object

Light also acts as a particle:

Different wave lengths have different energy (shorter wavelengths were able to knock off electrons from metal surface and long wavelengths could not)—different energy values: shorter lengths have more energy than the longer wave lengths

Similar properties: all photons, travel same speed, sometimes behave as particles and sometimes waves

-but because of their wavelength and thus their different energies, interact differently with matter

Longer-wavelengths penetrate through earth’s atmosphere (radio waves, some infrared radiation, visible light, and some uv)

Main objective of telescope: to capture light

Refracting telescope-collect light through lenses

-lenses still used in eyepieces of telescope to help brains accurately interpret what is seen, and in small telescopes at home(cameras etc)

Reflecting telescope-collect light through mirrors

-modern telescopes use mirrors for light collecting

-Concave mirror in shape of a parabola will cause incoming light to converge at a focal point

-if object is larger than a point, like moon or planet converge to a plane rather than a point

Larger mirror collects more light than a smaller one—light-gathering power related directly to primary mirror (mirror with twice the diameter of another mirror has 4x the area of the smaller mirror and collects 4x the light) A= Pi x d^2/4

measures clarity of image—smaller the angle the sharper the image (larger telescopes better)

make objects appear larger—related to resolution

Magnification= focal length of primary mirror/focal length of the eyepiece(larger better)

the brightness an object appears to have as viewed at a distance

(further away, the dimmer it looks)

Measure apparent brightness

Measure luminosity (need temperature, and need size of object)

Compare luminosity to apparent brightness to determine distance; problem is size of object is rarely known and is hard to measure