Stars, Galaxies, and Stars, Galaxies, and the Universethe Universe

Chapter 22Chapter 22

Page 752Page 752

Lesson 1 The SunLesson 1 The Sun

Local star-only star in our solar systemLocal star-only star in our solar system

Produces energy from hydrogenProduces energy from hydrogen

Much larger than any planetMuch larger than any planet

Contains 99.9% of the mass of solar Contains 99.9% of the mass of solar systemsystem

Has layers and atmosphereHas layers and atmosphere

Has sunspots and solar windsHas sunspots and solar winds

How is energy produced from How is energy produced from the Sun? the Sun?

Consists mostly of hydrogen and it Consists mostly of hydrogen and it turns into helium to produce energyturns into helium to produce energy

This change is created when This change is created when hydrogen particles collide (fusion)hydrogen particles collide (fusion)

The energy is the source of light and The energy is the source of light and warmth that make life possible on warmth that make life possible on EarthEarth

Sun’s InteriorSun’s Interior

Core: Center of Sun made from dense Core: Center of Sun made from dense gas, temps of 15 million degrees gas, temps of 15 million degrees CelsiusCelsius

Radiative Zone: Thick layer that Radiative Zone: Thick layer that energy passes through, hot and energy passes through, hot and dense, no fusion occursdense, no fusion occurs

Convection Zone: transfers energy by Convection Zone: transfers energy by moving heated gas/liquid moving heated gas/liquid (convection), carry energy to surface (convection), carry energy to surface

Sun’s ExteriorSun’s Exterior

Outer layers are the Sun’s Outer layers are the Sun’s atmosphere-much less dense atmosphere-much less dense

Photosphere: Visible layer of Sun, Photosphere: Visible layer of Sun, bumpy texturebumpy texture

Chromosphere: Thin middle layer, Chromosphere: Thin middle layer, gives off a pinkish lightgives off a pinkish light

Corona: Outer layer, extends several Corona: Outer layer, extends several million kilometers (p. 757)million kilometers (p. 757)

Sun’s FeaturesSun’s Features

Magnetic fields: near surfaceMagnetic fields: near surface Sunspots: on photosphere that are Sunspots: on photosphere that are

cooler areascooler areas Flares: eruptions of hot gas from the Flares: eruptions of hot gas from the

surface, near sunspotssurface, near sunspots Prominences: huge loops of gas that Prominences: huge loops of gas that

extend to the coronaextend to the corona Winds: electric particles that flow Winds: electric particles that flow

from the coronafrom the corona

AurorasAuroras

When solar winds enter our When solar winds enter our atmosphere, they release energy, atmosphere, they release energy, which can produce beautiful glowing which can produce beautiful glowing light in the sky. light in the sky.

Sometimes referred to the northern or Sometimes referred to the northern or southern lights since they occur near southern lights since they occur near the poles.the poles.

Can destroy orbiting satellites and Can destroy orbiting satellites and harm astronautsharm astronauts

Interesting FactsInteresting Facts

Takes sunlight about 8 minutes to Takes sunlight about 8 minutes to reach Earthreach Earth

Can only see chromosphere and Can only see chromosphere and corona light during solar eclipsecorona light during solar eclipse

Sunspot activity lasts about 11 yearsSunspot activity lasts about 11 years Solar winds extend throughout our Solar winds extend throughout our

atmosphereatmosphere

Lesson 2 Stars Lesson 2 Stars

Stars change over their life cycleStars change over their life cycle Classify stars by their characteristicsClassify stars by their characteristics Like our Sun, stars are huge balls of Like our Sun, stars are huge balls of

glowing gas that produce energy by glowing gas that produce energy by fusionfusion

Stars look like small points of light Stars look like small points of light because they are very far awaybecause they are very far away

Amount of light from a star and Amount of light from a star and distance determine brightness to usdistance determine brightness to us

Light YearLight Year

Distances between stars is measured Distances between stars is measured in light years by astronomersin light years by astronomers

It is the distance light travels in a It is the distance light travels in a yearyear

9.5 trillion kilometers or 6 trillion 9.5 trillion kilometers or 6 trillion milesmiles

Outside solar system, the closest star Outside solar system, the closest star to Earth is about 4 light years awayto Earth is about 4 light years away

ParallaxParallax

Another way astronomers measure Another way astronomers measure distancedistance

Shift in position of an object when Shift in position of an object when viewed from different locationsviewed from different locations

Plot positions from opposite sides of Plot positions from opposite sides of EarthEarth

Star Size Star Size

Giant and supergiant – larger than Giant and supergiant – larger than Sun- BetelgeuseSun- Betelgeuse

Dwarf-much smaller than the SunDwarf-much smaller than the Sun Betelgeuse is one of the brightest Betelgeuse is one of the brightest

stars even though it is 522 light stars even though it is 522 light yearsyears

Color/TemperatureColor/Temperature

Most stars appear whiteMost stars appear white Some are blue or red Some are blue or red Temperature determines colorTemperature determines color Cool-red, Hot- white, In between-blueCool-red, Hot- white, In between-blue Chart on page 765Chart on page 765

Life Cycle of a StarLife Cycle of a Star

Stars are not permanentStars are not permanent Birth, maturity and deathBirth, maturity and death Varies depending on the mass of the Varies depending on the mass of the

starstar

Birth-DeathBirth-Death

Form inside a cloud of gas and dust Form inside a cloud of gas and dust (nebula)(nebula)

Matter does not disappear at deathMatter does not disappear at death Matter forms another nebula or Matter forms another nebula or

combines with an existing starcombines with an existing star

Neutron StarNeutron Star

Collapsed core of a supergiant star Collapsed core of a supergiant star Emits visible lightEmits visible light High mass starHigh mass star

Black hole Black hole

A star with an extremely high mass A star with an extremely high mass leaves behind an invisible holeleaves behind an invisible hole

Astronomers can sometimes detect Astronomers can sometimes detect matter and energy around the hole matter and energy around the hole

Star SystemsStar Systems

Most stars do not exist alone Most stars do not exist alone Stars are held together by the force Stars are held together by the force

of gravity between themof gravity between them Binary system has 2 starsBinary system has 2 stars Multiple system has more than 2 Multiple system has more than 2

starsstars

Lesson 3 Galaxies Lesson 3 Galaxies

Galaxies have different sizes and Galaxies have different sizes and shapesshapes

Our solar system lies within the Milky Our solar system lies within the Milky Way galaxyWay galaxy

Galaxy is a huge group of stars, gas Galaxy is a huge group of stars, gas and dust held together by gravityand dust held together by gravity

Milky Way is shaped like a disk with a Milky Way is shaped like a disk with a bulge bulge

It has a hazy appearance It has a hazy appearance

Types of Galaxies Types of Galaxies

SpiralSpiral EllipticalElliptical IrregularIrregular Pictures on page 772Pictures on page 772

Center of GalaxiesCenter of Galaxies

Most large galaxies seem to have Most large galaxies seem to have supermassive black holes at their supermassive black holes at their centerscenters

Milky Way black hole = 3 million times Milky Way black hole = 3 million times the size of the Sunthe size of the Sun

Distant galaxies have bright centers Distant galaxies have bright centers called quasarscalled quasars

Quasar means “seems like a star”Quasar means “seems like a star” Galaxies sometimes collideGalaxies sometimes collide

Lesson 4 UniverseLesson 4 Universe

Galaxies are moving farther apart in Galaxies are moving farther apart in the universe meaning the universe is the universe meaning the universe is expandingexpanding

Universe is all space, energy and Universe is all space, energy and mattermatter

The universe does not expand into The universe does not expand into anything since there is nothing anything since there is nothing outside the universeoutside the universe

Doppler Effect Doppler Effect

Change in the observed wavelength Change in the observed wavelength or frequency of a wave that occurs or frequency of a wave that occurs when the source of the wave or the when the source of the wave or the observer is movingobserver is moving

Occurs with light and sound Occurs with light and sound Light wavelengths will seem Light wavelengths will seem

stretched of compressed while stretched of compressed while moving (p. 777)moving (p. 777)

ReviewReview

Read and study page 780Read and study page 780 Review on page 781 # 9-20Review on page 781 # 9-20

Keep notes titled, legible and Keep notes titled, legible and organizedorganized

Bring notes to class Bring notes to class