1. Chapter 1

2. Light- years are used to measure distances btwn. Celestial objects Light- years are used to measure distances btwn. Celestial objects Celestial objects in descending order: Celestial objects in descending order: – Universe – Galaxy – Nebula – Earth

3. Stars appears as smalls points of light Stars appears as smalls points of light Alpha Centauri is the closest star to the sun (triple- star system) Alpha Centauri is the closest star to the sun (triple- star system) – 4.3 light-years from Earth Our sun is a single-star system Our sun is a single-star system Most stars are paired stars called Binaries Most stars are paired stars called Binaries – Binary stars are double-stars systems How to you think astronomers view stars? Use Optical Telescopes (visible light)

4. Sirius/Dog Star, 8 light-years from Earth Sirius/Dog Star, 8 light-years from Earth – Twice size of the sun, brightest star in sky Polaris/North Star, 700+ light-years Polaris/North Star, 700+ light-years – Important in navigation – End of Little Dipper which is part of: – Ursa Minor/Little Bear – constellation of stars Group of stars which people can see at one time Group of stars which people can see at one time Imaginary figures Imaginary figures – Ursa Major/Big Bear – 7 stars of this make up the Big Dipper – 2 bright stars in the cup called Pointers → Polaris

5. Orion, the Hunter – seen on clear winter nights Orion, the Hunter – seen on clear winter nights – 2 bright stars in Orion: Betelgeuse Betelgeuse Rigel Rigel – Other close constellations are: Gemini, Canus Major/Big Dog, Canis Minor/Little Dog – Summer constellations: Scopius, Leo, Virgo Scopius, Leo, Virgo

6. Nova – stars that suddenly increase in brightness up to 100x for a short time then dims Nova – stars that suddenly increase in brightness up to 100x for a short time then dims – Almost all novas are binary systems – Gases from companion stars strike the other Nuclear explosion occurs creating: heat, light, & gases Nuclear explosion occurs creating: heat, light, & gases

7. 2 types of Star Clusters, appear as 1 star from Earth 1.Open Clusters Not well organizedNot well organized Hundreds of starsHundreds of stars PleiadesPleiades 2.Globular Clusters More commonMore common Spherical, round shapeSpherical, round shape 100,000+ stars100,000+ stars HerculesHercules

8. Huge clouds of dust that glow btwn stars Huge clouds of dust that glow btwn stars Birthplace of new stars Birthplace of new stars

9. Galaxies – major features of the universe Galaxies – major features of the universe – Contain various groups of stars – Milky Way – we live in – 100 billion + galaxies 3 Types of Galaxies: 3 Types of Galaxies: – Spiral – shaped like a pinwheel Andromeda Andromeda Milky Way Milky Way – Elliptical – spherical to flat in shape Very little dust & gas Very little dust & gas Older stars Older stars – Irregular – no orderly shape, less common Large and Small Magellanic Clouds closest to the Milky Way Large and Small Magellanic Clouds closest to the Milky Way

10. Planet Earth is in the Milky Way Planet Earth is in the Milky Way Older stars found near the center/nucleus Older stars found near the center/nucleus – Dense in stars – 20,000 light-years in diameter Milky Way 100,000 light-years across and 15,000 light-years thick Milky Way 100,000 light-years across and 15,000 light-years thick – 100,000 yrs to travel across @ speed of light Sun located in pinwheel arm abt. 30,000 light- years from center Sun located in pinwheel arm abt. 30,000 light- years from center – One of the youngest stars in Milky Way Spins counter clockwise Spins counter clockwise – Takes 200 million yrs to rotate 1 time around center

11. Spectroscope – breaks up light into its characteristic colors Spectroscope – breaks up light into its characteristic colors – Light focused into a beam by a lens then it passes through a prism then broken into a band of colors – Spectrum – band of colors formed when white light passes through a prism

12. All objects in the Universe are moving All objects in the Universe are moving Spectroscopes help to determine if galaxies or stars are moving toward or away from Earth Spectroscopes help to determine if galaxies or stars are moving toward or away from Earth

13. As light strikes the prism of the spectroscope, prism bends the light according to the wavelength of each color As light strikes the prism of the spectroscope, prism bends the light according to the wavelength of each color Stars moving fast toward Earth, light waves are compressed Stars moving fast toward Earth, light waves are compressed – Blue end of spectrum known as Blue Shift Stars moving away from Earth, light waves are expanded Stars moving away from Earth, light waves are expanded – Red end of spectrum known as Red Shift Doppler Effect – apparent change in wavelengths of light moving toward or away from Earth Doppler Effect – apparent change in wavelengths of light moving toward or away from Earth

14. Big Bang Theory states that the universe began to expand with the explosion of concentrated matter and energy and has been expanding ever since. Evidence Evidence – Expanding Universe – Background Radiation Based on the assumptions that our present universe is the result of expansion of matter from a single point Based on the assumptions that our present universe is the result of expansion of matter from a single point Astronomers believe that all galaxies are speeding away from the center of the Universe Astronomers believe that all galaxies are speeding away from the center of the Universe Gravity is the force that holds all galaxies together Gravity is the force that holds all galaxies together

15. Galaxies will continue to race outward Galaxies will continue to race outward Universe will continue to expand Universe will continue to expand Stars will eventually die, no more energy Stars will eventually die, no more energy Future means everything may eventually disappear in the universe Future means everything may eventually disappear in the universe

16. Gravity will eventually pull all galaxies back toward each other Gravity will eventually pull all galaxies back toward each other Blue shift will begin to be see Blue shift will begin to be see Matter & energy will again become packed into a small area and another big bang will occur Matter & energy will again become packed into a small area and another big bang will occur

17. Quasars – most distance objects from center of universe Quasars – most distance objects from center of universe – Abt 12 billion light-yrs from Earth – Quasar stands for quasi-stellar radio sources Gives off radio waves Gives off radio waves Quasi = something like Quasi = something like Stellar = star-like Stellar = star-like Quasars most mysterious objects in universe because they give off more energy that 100+ galaxies Quasars most mysterious objects in universe because they give off more energy that 100+ galaxies Light from a quasar 6 billion light-years from Earth has traveled more that 6 billion years to reach Earth Light from a quasar 6 billion light-years from Earth has traveled more that 6 billion years to reach Earth

18. 200 billion billion stars in the Universe 200 billion billion stars in the Universe Stars differ in many features: Stars differ in many features: – Size – Mass – Color – Temperature – Brightness

19. 5 main groups of size 5 main groups of size 1.Super Giant (largest) –1000 times size of sun –Die quickly due to size 2.Giant –10 – 100 times size of sun 3.Sun-sized (medium) –Most abundant 4.White dwarf –Smaller than Earth –Smallest white dwarf Van Mannen’s star 5.Neutron (smallest) –Abt. 16 km

20. Elements have “fingerprints” Elements have “fingerprints” – Creating certain color lines passed through the spectroscope when burned Hydrogen is most common element in stars Hydrogen is most common element in stars – 60-80% of total mass Helium is 2 nd most common element Helium is 2 nd most common element Both elements make up abt 96 -99 % of star’s mass Both elements make up abt 96 -99 % of star’s mass

21. Star’s color help to determine surface temperature of a star Star’s color help to determine surface temperature of a star – Color is related to surface temperature Surface temp. much lower that core temp. Surface temp. much lower that core temp. – Ex. Sun Surface temperature abt 6000°C Surface temperature abt 6000°C Core temperature abt. 15,000,000°C Core temperature abt. 15,000,000°C – Hottest star abt. 50,000 °C – Coolest star abt. 3,000°C – Most stars somewhere in between

22. Brightness depends on size of star, surface temperature, distance from Earth Brightness depends on size of star, surface temperature, distance from Earth Apparent Magnitude – brightness of a star as it appears from Earth Apparent Magnitude – brightness of a star as it appears from Earth Absolute Magnitude – amount of light a star actually gives off Absolute Magnitude – amount of light a star actually gives off Most stars brightness is constant Most stars brightness is constant Variable stars brightness varies Variable stars brightness varies – North Star/Polaris is a Pulsating Variable star that changes size and brightness

23. Ejnar Hertzsprung – Danish astronomer Ejnar Hertzsprung – Danish astronomer Henry Norris Russell – American astronomer Henry Norris Russell – American astronomer Both found that as absolute magnitude of stars increase the temperature of stars also increases Both found that as absolute magnitude of stars increase the temperature of stars also increases Definite patterns formed called the Hertzsprung- Russell diagram Definite patterns formed called the Hertzsprung- Russell diagram – Temperature plotted on horizontal axis – Absolute magnitude on vertical axis Main-sequence stars are found in the upper left corner to the lower right corner Main-sequence stars are found in the upper left corner to the lower right corner

24. Parallax – used to measure distance to stars Parallax – used to measure distance to stars – Refers to the apparent change in the position in the sky, Earth’s position not movement of star Brightness of the star is also used to measure distance Brightness of the star is also used to measure distance – Use apparent and absolute magnitude in a complicated formula

25. – Very strong gravitational forces in the core of stars – Gravity pulls together atoms of Hydrogen gas so tightly they become fused Nuclear Fusion – hydrogen atoms are fused to form helium atoms Nuclear Fusion – hydrogen atoms are fused to form helium atoms – Hydrogen changed into Helium at a huge rate but a large amt of Hydrogen is lost. Lost Hydrogen changed into energy in the form of heat and light Lost Hydrogen changed into energy in the form of heat and light – This is why stars shine Fusion within an aging red giant star causes temperature in the core of the star to rise Fusion within an aging red giant star causes temperature in the core of the star to rise

26. Layers of the Sun Layers of the Sun – Ball-shaped object made of extremely hot gases – 4 main layers of sun Corona – outermost layer of sun’s atmosphere Corona – outermost layer of sun’s atmosphere Chromosphere – 2 nd layer of sun’s atmosphere Chromosphere – 2 nd layer of sun’s atmosphere Photosphere – innermost layer of sun’s atmosphere Photosphere – innermost layer of sun’s atmosphere Core – center of the sun Core – center of the sun

27. Calm star Calm star Prominences – solar storm, seen as huge bright arches/loops of gas Prominences – solar storm, seen as huge bright arches/loops of gas Solar Flares – solar storm, bright bursts of light on sun’s surface Solar Flares – solar storm, bright bursts of light on sun’s surface – Lasts less than 1 hour Solar Winds – continuous stream of high-energy particles released into space Solar Winds – continuous stream of high-energy particles released into space Sunspots – dark, cooler areas on sun’s surface Sunspots – dark, cooler areas on sun’s surface – Storms in the lower atmosphere of sun Sun rotates on an axis like the Earth Sun rotates on an axis like the Earth – Gases rotate once every 25 days

28. Life cycle of stars from “birth” to “death” Life cycle of stars from “birth” to “death”

29. New stars form from gases in a nebula New stars form from gases in a nebula – Hydrogen gets clumped together by gravity – Begin spinning in a cloud formation – Collision heat up and nuclear fusion occurs Protostar – great heat that is given off during nuclear fusion causing a new star Protostar – great heat that is given off during nuclear fusion causing a new star

30. Life cycle of star is now fixed Life cycle of star is now fixed Main factor that shapes the evolution of a star is how much mass it began with. Main factor that shapes the evolution of a star is how much mass it began with. Stars shine with a red color when most of the hydrogen gas has been converted into helium Stars shine with a red color when most of the hydrogen gas has been converted into helium Star begins to grow and heats up becoming a giant red star Star begins to grow and heats up becoming a giant red star As giant red continues to age the temperature of the Helium core rises to abt 200,000,000°C As giant red continues to age the temperature of the Helium core rises to abt 200,000,000°C – Causing carbon atoms to form – Star begins to die – Gravity causes matter to collapse inward squeezing tightly becoming White Dwarf

31. Matter extremely dense Matter extremely dense Not a dead star, shines with hot white light Not a dead star, shines with hot white light Stars will slowly die Stars will slowly die Life span range: Life span range: – 10 billion – 100 billion yrs

32. Mass of massive stars 6x that of sun Mass of massive stars 6x that of sun Take same path as medium-sized stars except for after red giant stage they do not become white dwarfs Take same path as medium-sized stars except for after red giant stage they do not become white dwarfs Carbon atoms continue to fuse creating heavier elements like oxygen & nitrogen Carbon atoms continue to fuse creating heavier elements like oxygen & nitrogen Core of massive star so hot that fusion continues until the heavy element of iron is formed Core of massive star so hot that fusion continues until the heavy element of iron is formed

33. Massive stars begin falling apart Massive stars begin falling apart Supernova - tremendous explosion occurs Supernova - tremendous explosion occurs – Lights up sky for weeks – Most famous supernova on record observed in 1054 by a Chinese astronomer lit the sky for 23 days and seen at night for more that 600 days lit the sky for 23 days and seen at night for more that 600 days Crab Nebula – remains of this supernova Crab Nebula – remains of this supernova

34. Neutron stars are the result of supernovas Neutron stars are the result of supernovas – Very dense – Spin rapidly, giving off radio waves as pulses – Pulsars – neutron stars that give off bursts of radio waves

35. Black Hole – swallows matter and energy as if a cosmic vacuum cleaner Black Hole – swallows matter and energy as if a cosmic vacuum cleaner – Result from death of super massive stars – No light escapes but sometimes have a companion star Helps astronomers to find black holes Helps astronomers to find black holes