Diffraction Grating bends white light coming from an

Diffraction Grating • bends white light coming from an object • separates the light into the wavelengths (colors) of the visible light spectrum

10/4/16 ELECTROMAGNETIC SPECTRUM AND ASTRONOMIC DISTANCES Objective: I will diagram the electromagnetic spectrum. I will compare the different measurement units used to measure distances in space. PAGE 21

Light • Light is electromagnetic energy • travels in waves • photon- basic particle of light

Electromagnetic Spectrum • range of all the wavelengths of light given off by objects

Electromagnetic Spectrum • Radio • Microwave • Infrared • Visible (ROY G. BIV) • Ultraviolet • X-ray • Gamma

Radio • longest wavelength, lowest energy

Microwave • Used by astronomers to map the early universe

Infrared • used to detect heat coming from objects

Visible Light • light we can detect with our eyes Longer Wavelength Shorter Wavelength (ROY G. BIV)

Ultraviolet • given off by the Sun, causes sunburn

X-Ray • helps in the field of medicine

Gamma Rays • shortest wavelength, highest energy

10/4/16 ELECTROMAGNETIC SPECTRUM AND ASTRONOMIC DISTANCES Objective: I will diagram the electromagnetic spectrum. I will compare the different measurement units used to measure distances in space. PAGE 21

Distances in Space • In astronomy, scientists rarely use kilometers • too small! • only use km for diameters of planets or how far away a moon is from the planet

Astronomical Unit • the distance from the earth to the sun • 1 AU = 93 million miles • used to measure distances between planets

Light Year • distance light travels in one year • measure of distance, NOT time • Speed of light is 3 x 108 m/s

Light Year • used to measure distances between stars and galaxies

Light Year • If light travels 300, 000 km/s, how far does light travel in one year? This distance you calculate is the distance of one light-year. • Show all of your work and answers on page 20.