Chapter 27 Notes - mitchell.k12.in.us

Chapter 27 Notes The Sun-Earth-Moon System Tools of Astronomy Astronomers study radiation (light) emitted or reflected by distant objects Visible light, radio waves, X-rays, UV, infrared, microwaves, and gamma rays are all types of

electromagnetic radiation (EMR) All EMR travels at the speed of light Different types of telescopes detect different types of EMR The Electromagnetic Spectrum Telescopes

A telescopes purpose is not to magnify objects, but to collect and focus light. Visible light: Refracting (lenses) Reflecting (mirrors) Radio telescopes:

Space-based Telescopes Earths atmosphere blocks some types of EMR can distort visible light; some telescopes are located above the atmosphere. Here are a few of them: Hubble: visible light

Chandra: X-rays Spitzer: Infrared Space-Based Astronomy Robotic spacecraft Cassini (Saturn): 2005 Mars Reconnaissance Orbiter: 2006

New Horizons (Pluto): 2006 Human space flight International Space Station Spinoff technology More than 1400 different NASA technologies passed on to commercial industries

Exploring the Moon History of the Moon The Moon is about the same age as the Earth (4.5 billion years old) Interior: layered, but no tectonic activity Surface:

Highlands: mountains Maria: impact basins filled with lava Rilles: valleys created by flowing lava Moon Map Moon Map A Mercator map of the Moon

Formation of the Moon Impact Theory: Currently accepted theory based on the Moons geology and computer

simulations Time is based on Astronomy

Day: one complete rotation (plus ~4minutes) Year: one complete orbit around the Sun Month: based on one cycle of lunar phases Seasons: caused by Earths tilt Solstices: summer and winter Equinoxes: equal night spring and fall Suns maximum height is called the zenith.

The zenith varies depending on latitude and time of year Moon Phases Waxing: getting larger Waning: getting smaller

Crescent: less than size Gibbous: greater than size Lunar month vs. sidereal month It takes 27.3 days

for the Moon to make one complete orbit around the Earth It takes 29.5 days for the Moon to complete one cycle of phases

Synchronous orbit The same side of the Moon always faces the Earth The Moon spins one time on its axis each time it goes around

the Earth There is no dark side of the Moon Solar Eclipse Earth passes through Moons shadow We see the Sun blocked Only occurs during new moon phase (why

not every new moon phase?) Lunar Eclipse Moon passes through Earths shadow We see the Moon darkened Only occurs during full moon phase