Astronomy Chapter 2Astronomy Chapter 2The Solar SystemThe Solar System

Observing the Solar SystemObserving the Solar System

Section 1Section 1

VocabularyVocabulary

Geocentric: A description of the solar system in Geocentric: A description of the solar system in which all of the planets revolve around Earthwhich all of the planets revolve around Earth

Ellipse: An elongated circle, or oval shape; the Ellipse: An elongated circle, or oval shape; the shape of the planets’ orbitsshape of the planets’ orbits

Heliocentric: A description of the solar system in Heliocentric: A description of the solar system in which all of the planets revolve around the sunwhich all of the planets revolve around the sun

Intertia: the tendency of a moving object to Intertia: the tendency of a moving object to continue in a straight line or a stationary object continue in a straight line or a stationary object to remain in placeto remain in place

Main IdeasMain Ideas

Ptolemy thought that Earth is at the center of the Ptolemy thought that Earth is at the center of the system of planetssystem of planets

Copernicus thought that the sun is at the center Copernicus thought that the sun is at the center of the planets. Galileo’s observations supported of the planets. Galileo’s observations supported Copernicus’s theory.Copernicus’s theory.

Kepler discovered that the orbits of the planets Kepler discovered that the orbits of the planets are ellipsesare ellipses

Newton concluded that two factors—inertia and Newton concluded that two factors—inertia and gravity—combine to keep the planets in orbitgravity—combine to keep the planets in orbit

Guiding QuestionsGuiding Questions

How is Copernicus’s description of the system of How is Copernicus’s description of the system of planets different from Ptolemy’s description?planets different from Ptolemy’s description?

How did Galileo’s observations of Jupiter’s How did Galileo’s observations of Jupiter’s moons help to show that the geocentric moons help to show that the geocentric explanation is incorrect?explanation is incorrect?

What shape are the orbits of the planets? How What shape are the orbits of the planets? How was the discovery of this orbit shape made?was the discovery of this orbit shape made?

What two factors act together to keep the What two factors act together to keep the planets in orbit around the sun? planets in orbit around the sun?

The SunThe SunSection 2Section 2

VocabularyVocabulary

Nuclear fusion: the process by which hydrogen Nuclear fusion: the process by which hydrogen atoms join together to form helium, releasing atoms join together to form helium, releasing energyenergy

Core: the central part of the sun, where nuclear Core: the central part of the sun, where nuclear fusion occursfusion occurs

Photosphere: the inner layer of he sun’s Photosphere: the inner layer of he sun’s atmosphereatmosphere

Chromosphere: the middle layer of the sun’s Chromosphere: the middle layer of the sun’s atmosphereatmosphere

Corona: the outer layer of the sun’s atmosphereCorona: the outer layer of the sun’s atmosphere

VocabularyVocabulary

Solar wind: a stream of electrically charged Solar wind: a stream of electrically charged particles produced by the sun’s coronaparticles produced by the sun’s corona

Sunspot: A dark area of gas on the sun that is Sunspot: A dark area of gas on the sun that is cooler than surrounding gasescooler than surrounding gases

Prominence: a loop of gas that protrudes from Prominence: a loop of gas that protrudes from the sun’s surface, linking parts of sunspot the sun’s surface, linking parts of sunspot regionsregions

Solar flare: an explosion of hydrogen gas from Solar flare: an explosion of hydrogen gas from the sun’s surface that occurs when lops in the sun’s surface that occurs when lops in sunspot regions suddenly connectsunspot regions suddenly connect

Main IdeasMain Ideas

The sun’s energy comes from nuclear The sun’s energy comes from nuclear fusionfusion

The sun’s atmosphere has three layers: The sun’s atmosphere has three layers: the photosphere, the chromosphere, and the photosphere, the chromosphere, and the coronathe corona

Features on or above the sun’s surface Features on or above the sun’s surface include sunspots, prominences, and solar include sunspots, prominences, and solar flaresflares

Guiding QuestionsGuiding Questions

How is energy produced in the sun’s core?How is energy produced in the sun’s core?Name the layers of the sun’s atmosphere.Name the layers of the sun’s atmosphere.What is the solar wind?What is the solar wind?Describe three features found on or above Describe three features found on or above

the surface of the sun.the surface of the sun.Why do sunspots look darker than the rest Why do sunspots look darker than the rest

of the sun’s photosphere?of the sun’s photosphere?How does the number of sunspots change How does the number of sunspots change

over time? over time?

The Inner PlanetsThe Inner PlanetsSection 3Section 3

VocabularyVocabulary

Terrestrial planets: the name given to the Terrestrial planets: the name given to the four inner planets, Mercury, Venus, Earth, four inner planets, Mercury, Venus, Earth, and Marsand Mars

Retrograde rotation: The spinning motion Retrograde rotation: The spinning motion of a planet from east to west, opposite to of a planet from east to west, opposite to the rotation of most planets and moonsthe rotation of most planets and moons

Greenhouse effect: the trapping of heat by Greenhouse effect: the trapping of heat by a planet’s atmospherea planet’s atmosphere

Main IdeasMain Ideas

The four inner planets—Mercury, Venus, The four inner planets—Mercury, Venus, Earth, and Mars—are small and have Earth, and Mars—are small and have rocky surfaces. They are often called the rocky surfaces. They are often called the terrestrial planetsterrestrial planets

Guiding QuestionsGuiding Questions

What features do all of the inner planets have in What features do all of the inner planets have in common?common?

What is Mercury’s atmosphere like? ExplainWhat is Mercury’s atmosphere like? Explain Why can astronomers see the surface of Mars Why can astronomers see the surface of Mars

clearly, but not the surface of Venus?clearly, but not the surface of Venus? How have astronomers been able to study the How have astronomers been able to study the

surface of Venus?surface of Venus? What evidence do astrnomomers have that What evidence do astrnomomers have that

water once flowed on Mars?water once flowed on Mars?

The Outer PlanetsThe Outer PlanetsSection 4Section 4

VocabularyVocabulary

Gas Giant: the name given to the first four Gas Giant: the name given to the first four outer planets: Jupiter, Saturn, Uranus, and outer planets: Jupiter, Saturn, Uranus, and NeptuneNeptune

Main IdeasMain Ideas

Four outer planets—Jupiter, Saturn, Four outer planets—Jupiter, Saturn, Uranus, and Neptune—are much larger Uranus, and Neptune—are much larger than Earththan Earth

Pluto and Charon have solid surfaces and Pluto and Charon have solid surfaces and masses much less than that of Earthmasses much less than that of Earth

Guiding QuestionsGuiding Questions

How are the gas giants similar to each How are the gas giants similar to each other? How are they different?other? How are they different?

How is Pluto different from the gas giants?How is Pluto different from the gas giants?What is the most prominent feature of What is the most prominent feature of

Jupiter’s surface? What cuases this Jupiter’s surface? What cuases this feature?feature?

Why do astrnomoers think Uranus may Why do astrnomoers think Uranus may have been hit by another object billions of have been hit by another object billions of years ago?years ago?

Comets, Asteroids, and MeteorsComets, Asteroids, and MeteorsSection 5Section 5

VocabularyVocabulary Comet a ball of ice and dust whose orbit is a long narrow Comet a ball of ice and dust whose orbit is a long narrow

ellipseellipse Asteroid: objects revolving around the sun that are too Asteroid: objects revolving around the sun that are too

small and too numerous to be considered planetssmall and too numerous to be considered planets Asteroid belt: the region of the solar system between the Asteroid belt: the region of the solar system between the

orbits of Mars and Jupiter, where many asteroids are orbits of Mars and Jupiter, where many asteroids are foundfound

Meteoroid: a chunk of rock or dust in spaceMeteoroid: a chunk of rock or dust in space Meteor: a streak of light in the sky produced by the Meteor: a streak of light in the sky produced by the

burning of a meteoroid in Earth’s atmosphereburning of a meteoroid in Earth’s atmosphere Meteorites: a meteoroid that has hit Earth’s surfaceMeteorites: a meteoroid that has hit Earth’s surface

Main IdeasMain Ideas

Comets are chunks of ice and dust that Comets are chunks of ice and dust that usually have long, elliptical orbitsusually have long, elliptical orbits

Most asteroids revolve around the sun Most asteroids revolve around the sun between the orbits of Mars and Jupiterbetween the orbits of Mars and Jupiter

Guiding QuestionsGuiding Questions

What is a comet made of?What is a comet made of?Where are most asteroids found?Where are most asteroids found?What are the main sources of meteoroids?What are the main sources of meteoroids?What is the difference between a meteor What is the difference between a meteor

and a meteorite?and a meteorite?

Is There Life Beyond Earth?Is There Life Beyond Earth?Section 6Section 6

VocabluarlyVocabluarly

Extraterrestrial Life: life that arises outside Extraterrestrial Life: life that arises outside of Earthof Earth

Main IdeasMain Ideas

Earth has liquid water and a suitable Earth has liquid water and a suitable temperature range and atmosphere for temperature range and atmosphere for living things to survive. living things to survive.

Since life as we know it requires water, Since life as we know it requires water, scientists hypothesize that mars may have scientists hypothesize that mars may have once had the conditions for life to existonce had the conditions for life to exist

Guiding QuestionsGuiding Questions

What conditions does life on Earth need to What conditions does life on Earth need to survive?survive?

Why do astronomers think there could be Why do astronomers think there could be life on Europa?life on Europa?

How did the How did the VikingViking missions search fro life missions search fro life on Mars?on Mars?