Stars, Galaxies, and the Universe Chapter 22 Page 752

Lesson 1 The Sun Local star-only star in our solar system Produces energy from hydrogen Much larger than any planet Contains 99.9% of the mass of solar system Has layers and atmosphere Has sunspots and solar winds

How is energy produced from the Sun? Consists mostly of hydrogen and it turns into helium to produce energy Consists mostly of hydrogen and it turns into helium to produce energy This change is created when hydrogen particles collide (fusion) This change is created when hydrogen particles collide (fusion) The energy is the source of light and warmth that make life possible on Earth The energy is the source of light and warmth that make life possible on Earth

Sun’s Interior Core: Center of Sun made from dense gas, temps of 15 million degrees Celsius Core: Center of Sun made from dense gas, temps of 15 million degrees Celsius Radiative Zone: Thick layer that energy passes through, hot and dense, no fusion occurs Radiative Zone: Thick layer that energy passes through, hot and dense, no fusion occurs Convection Zone: transfers energy by moving heated gas/liquid (convection), carry energy to surface Convection Zone: transfers energy by moving heated gas/liquid (convection), carry energy to surface

Sun’s Exterior Outer layers are the Sun’s atmosphere- much less dense Outer layers are the Sun’s atmosphere- much less dense Photosphere: Visible layer of Sun, bumpy texture Photosphere: Visible layer of Sun, bumpy texture Chromosphere: Thin middle layer, gives off a pinkish light Chromosphere: Thin middle layer, gives off a pinkish light Corona: Outer layer, extends several million kilometers (p. 757) Corona: Outer layer, extends several million kilometers (p. 757)

Sun’s Features Magnetic fields: near surface Magnetic fields: near surface Sunspots: on photosphere that are cooler areas Sunspots: on photosphere that are cooler areas Flares: eruptions of hot gas from the surface, near sunspots Flares: eruptions of hot gas from the surface, near sunspots Prominences: huge loops of gas that extend to the corona Prominences: huge loops of gas that extend to the corona Winds: electric particles that flow from the corona Winds: electric particles that flow from the corona

Auroras When solar winds enter our atmosphere, they release energy, which can produce beautiful glowing light in the sky. When solar winds enter our atmosphere, they release energy, which can produce beautiful glowing light in the sky. Sometimes referred to the northern or southern lights since they occur near the poles. Sometimes referred to the northern or southern lights since they occur near the poles. Can destroy orbiting satellites and harm astronauts Can destroy orbiting satellites and harm astronauts

Interesting Facts Takes sunlight about 8 minutes to reach Earth Takes sunlight about 8 minutes to reach Earth Can only see chromosphere and corona light during solar eclipse Can only see chromosphere and corona light during solar eclipse Sunspot activity lasts about 11 years Sunspot activity lasts about 11 years Solar winds extend throughout our atmosphere Solar winds extend throughout our atmosphere

Lesson 2 Stars Stars change over their life cycle Stars change over their life cycle Classify stars by their characteristics Classify stars by their characteristics Like our Sun, stars are huge balls of glowing gas that produce energy by fusion Like our Sun, stars are huge balls of glowing gas that produce energy by fusion Stars look like small points of light because they are very far away Stars look like small points of light because they are very far away Amount of light from a star and distance determine brightness to us Amount of light from a star and distance determine brightness to us

Light Year Distances between stars is measured in light years by astronomers Distances between stars is measured in light years by astronomers It is the distance light travels in a year It is the distance light travels in a year 9.5 trillion kilometers or 6 trillion miles 9.5 trillion kilometers or 6 trillion miles Outside solar system, the closest star to Earth is about 4 light years away Outside solar system, the closest star to Earth is about 4 light years away

Parallax Another way astronomers measure distance Another way astronomers measure distance Shift in position of an object when viewed from different locations Shift in position of an object when viewed from different locations Plot positions from opposite sides of Earth Plot positions from opposite sides of Earth

Star Size Giant and supergiant – larger than Sun- Betelgeuse Giant and supergiant – larger than Sun- Betelgeuse Dwarf-much smaller than the Sun Dwarf-much smaller than the Sun Betelgeuse is one of the brightest stars even though it is 522 light years Betelgeuse is one of the brightest stars even though it is 522 light years

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

Life Cycle of a Star Stars are not permanent Stars are not permanent Birth, maturity and death Birth, maturity and death Varies depending on the mass of the star Varies depending on the mass of the star

Birth-Death Form inside a cloud of gas and dust (nebula) Form inside a cloud of gas and dust (nebula) Matter does not disappear at death Matter does not disappear at death Matter forms another nebula or combines with an existing star Matter forms another nebula or combines with an existing star

Neutron Star Collapsed core of a supergiant star Collapsed core of a supergiant star Emits visible light Emits visible light High mass star High mass star

Black hole A star with an extremely high mass leaves behind an invisible hole A star with an extremely high mass leaves behind an invisible hole Astronomers can sometimes detect matter and energy around the hole Astronomers can sometimes detect matter and energy around the hole

Star Systems Most stars do not exist alone Most stars do not exist alone Stars are held together by the force of gravity between them Stars are held together by the force of gravity between them Binary system has 2 stars Binary system has 2 stars Multiple system has more than 2 stars Multiple system has more than 2 stars

Lesson 3 Galaxies Galaxies have different sizes and shapes Galaxies have different sizes and shapes Our solar system lies within the Milky Way galaxy Our solar system lies within the Milky Way galaxy Galaxy is a huge group of stars, gas and dust held together by gravity Galaxy is a huge group of stars, gas and dust held together by gravity Milky Way is shaped like a disk with a bulge Milky Way is shaped like a disk with a bulge It has a hazy appearance It has a hazy appearance

Types of Galaxies Spiral Spiral Elliptical Elliptical Irregular Irregular Pictures on page 772 Pictures on page 772

Center of Galaxies Most large galaxies seem to have supermassive black holes at their centers Most large galaxies seem to have supermassive black holes at their centers Milky Way black hole = 3 million times the size of the Sun Milky Way black hole = 3 million times the size of the Sun Distant galaxies have bright centers called quasars Distant galaxies have bright centers called quasars Quasar means “seems like a star” Quasar means “seems like a star” Galaxies sometimes collide Galaxies sometimes collide

Lesson 4 Universe Galaxies are moving farther apart in the universe meaning the universe is expanding Galaxies are moving farther apart in the universe meaning the universe is expanding Universe is all space, energy and matter Universe is all space, energy and matter The universe does not expand into anything since there is nothing outside the universe The universe does not expand into anything since there is nothing outside the universe

Doppler Effect Change in the observed wavelength or frequency of a wave that occurs when the source of the wave or the observer is moving Change in the observed wavelength or frequency of a wave that occurs when the source of the wave or the observer is moving Occurs with light and sound Occurs with light and sound Light wavelengths will seem stretched of compressed while moving (p. 777) Light wavelengths will seem stretched of compressed while moving (p. 777)

Review Read and study page 780 Read and study page 780 Review on page 781 # 9-20 Review on page 781 # 9-20 Keep notes titled, legible and organized Keep notes titled, legible and organized Bring notes to class Bring notes to class