Unit C: Observing the Sky Chapter 5: The Earth-Moon System Science 6 Unit C: Observing the Sky Chapter 5: The Earth-Moon System

Lesson 1: Tools of Astronomy Terms: Universe Telescope Refraction Reflection Wavelength Frequency Electromagnetic Spectrum

Lesson 1: Tools of Astronomy What Is Astronomy? Astronomy: the study of the universe Universe: everything that exists—Earth and all things in space Astronomers study different parts of the universe

Astronomers As a career For fun Curiosity Navigation

Observing the Universe Using the eyes Telescope: device that collects light and makes distance objects appear closer Send robots or humans

Models, Theories, Hypothesis Models, theories, hypothesis used to explain observations Models simply world Theory: well-tested scientific explanation Hypothesis: scientific explanation that has not been fully tested Theory can change when new evidence does not support the old theory’s predictions

What Is Light? Electromagnetic Radiation: light Light may be invisible and includes radio waves, infrared waves, ultraviolet waves, x-rays, gamma rays Light travels through space at: 300,000km/sec (186,000 miles/sec) No matter travels faster Takes 8 minutes for light to travel from the Sun to the Earth Other stars’ light may take years to reach Earth

Light as a Wave Light waves do not need a medium (something to travel through) the wave can travel through empty space Opaque: light does not travel through Translucent: light travels through; object unclear Transparent: light travels through; object clear Refraction: “bending” of light Ex. Light thru prism Reflection: “bouncing off” of light Ex. Mirror

Light travels in waves Wavelength: Distance from one peak to the next Frequency: Number of waves that pass by a point in an amount of time—measured in hertz Longer the wavelength-- lower the frequency

The Electromagnetic Spectrum Electromagnetic spectrum: diagram that shows waves of light in order of wavelength and frequency Different wavelengths have special names and properties Radio, Infrared, Visible, UV, x-ray, gamma rays

Electromagnetic Spectrum

How do telescopes work? Reflecting telescope uses mirror and lens to magnify objects Refracting telescope uses lens to magnify images. The lens bend light as it travels through it. http://study.com/academy/lesson/refracting-reflecting-telescopes-key-concepts.html

What Instruments Detect Invisible Light? Eye—detects visible light Telescopes made to detect other waves than visible light Different information can be gathered by making observations of each part of electromagnetic spectrum

How do we get information from space? Probes and satellites that go beyond Earth’s atmosphere Satellites and probes are unmanned space crafts Space shuttle manned space craft Hubble Space Telescope—orbits above most of Earth’s atmosphere http://www.nasa.gov/mission_pages/hubble/main/index.html http://hubble25th.org/

What would life on a space flight be like? Survival Requires: water, food, oxygen

What have we done in space so far? Sputnik-1: First artificial satellite 1957 USSR Apollo-II: First human landing on the moon 1969 USA

https://www.youtube.com/watch?v=sTBIr65cL_E

Lesson 2: Earth and Sun Terms: Rotation Standard Time Zone International Date Line Revolution

How Do We Know Earth is Rotating? Earth rotates on its axis (Axis—imaginary line through the Earth from N Pole to S Pole) 24hours for Earth to make one rotation Evidence Satellite Images from Space Foucault pendulum Earth’s shape “Movement” of the Sun—rises in east and sets in west

What Are Standard Time Zones? Earth spins to the East Rotates 360 degrees in 24 hours—15degrees/hr Standard Time Zone: a belt 15 degrees wide in longitude—places all have same time One-hour time zone that are next to each other Travel west turn back (subtract) Travel east turn forward (add) International Date Line: location where new day begins—180 degrees line of longitude

Why Are There Seasons? Seasons NOT caused by change in distance from the Sun Revolution: Earth’s one trip around the Sun Earth is tilted at 23 ½ degrees Revolution of the tilted Earth around the Sun causes the Seasons When N. Hemisphere is tilted towards the Sun—N. Hemisphere has summer When N. Hemisphere is tilted away from the Sun—N. Hemisphere has winter

Where is the Sun in the Summer and in Winter? Steeper the angles of Sun’s rays the higher the Sun appears in the sky One side of the Earth experiences day while the other experiences night Tell time by knowing position of the Sun in sky https://www.youtube.com/watch?v=KUU7IyfR34o

How is the Sun an Important Energy Source? Sun is the energy source for life on Earth Plants convert sunlight to sugar (Producers) Animals eat plants for energy (Consumers) Fossil Fuels (coal, oil, natural gas) formed from decayed ancient living things Sun is energy source for water cycle Uneven heating of Earth’s surface causes wind and contributes to ocean currents

Lesson 3: The Moon In Motion Terms: Phase Lunar Eclipse Solar Eclipse Tide

Why Does the Moon Change Its Appearance? Moon revolves around Earth Earth revolves around the Sun Moon’s appearance changes appearance on monthly cycle Phase: shape of the lighted part of the moon

Why Does the Moon Change Its Appearance? Half of the Moon always lighted by the Sun Can’t always see all half The position of the Sun, the Moon, and Earth determine the phase

Why Does the Moon Change Its Appearance? Half of the Moon always lighted by the Sun Can’t always see all half The position of the Sun, the Moon, and Earth determine the phase

Why Does the Moon Change Its Appearance? New Moon: Moon between Earth and Sun Cannot see any of the Moon’s lit half Waxing Phase: more than New Moon but less that first quarter; “growing larger” Waning Phase: less than full Moon phase but more than third quarter; “growing smaller”

What Are Eclipses? Twice a year the Moon crosses the path of Earth’s orbit Lunar Eclipse: Moon becomes dark for time until it moves out of Earth’s shadow

What Are Eclipses? Solar Eclipse: Earth passes through Moon’s shadow; Moon must be in straight line between Sun and Earth

What are tides? Tides: regular rise and fall of water levels along a shore Tide caused from pull between Earth and Moon

What are tides? Spring tide: higher than usual tide Neap tide: lower than usual tide

What Does the Moon’s Surface Look Like? Observations made by telescopes and astronauts Crater: formed by impact of space objects Maria: large, dark flat areas Highlands: light-colored cratered area at high levels Mountains: named after Earth’s mountain ranges Valleys: cigar-shaped depresions