Vocabulary The words are in lesson order with the lesson the word is from written as: – L # 1

light-year – L 1  The distance that light travels in one year, about 9.46 trillion kilometers  Is a unit of distance NOT time 2

parallax – L 1  The apparent change in position of an object when you look at it from different places 3

scientific notation – L 1  Uses powers of 10 to write very large numbers in shorter form  Example: 37,000,000,000, x

universe – L 1  All of space and everything in it 5

binary star – L 2 Star systems that have 2 stars, called double stars Often 1 of the stars is much brighter & more massive solarsystem.nasa.gov 6

elliptical galaxy – L 2 It looks round and flattened Billions of stars They don’t have much gas or dust between the stars Contains old stars solarsystem.nasa.gov 7

galaxy – L 2  A huge group of single stars, star systems, star clusters, dust, and gas, bound together by gravity  solarsystem.nasa.gov 8

irregular galaxy – L 2 They are not regular shapes; smaller Contains you, bright stars Includes a lot of gas & dust to form new stars solarsystem.nasa.gov 9

planet – L 2 An object that orbits a star Large enough to have become rounded by its own gravity Has cleared the area of its orbit solarsystem.nasa.gov 10

quasar – L 2 Active, young galaxies with black holes at their center Gas spins around the black hole Heats up, & glows solarsystem.nasa.gov 11

solar system – L 2 Contains a star and the planets and other objects that revolve around the star solarsystem.nasa.gov 12

spiral galaxy – L 2 Looks like a pinwheel Its arms are full of young stars & new stars form there solarsystem.nasa.gov 13

star – L 2 A giant ball of gas in a small volume Primarily composed of hydrogen and helium, which undergoes nuclear fusion (combining) solarsystem.nasa.gov 14

 The process of building something up gradually by the gathering together of smaller pieces 15

 A push or a pull 16

 The force that pulls objects towards each other  The strength of the force of gravity between 2 objects depends on the masses of the objects & the distance between the 2 objects 17

 The tendency of an object to resist a change in motion  Example: when a car stops suddenly, you keep moving forward 18

 Every object n the universe attract every other object 19

 An object at rest will stay at rest and an object in motion will stay in motion; unless acted upon 20

 The path of an object as it revolves around another object in space 21

absolute brightness – L 4 Also known as luminosity It is the brightness that a star would have if it were at a standard distance from Earth solarsystem.nasa.gov 22

apparent brightness – L 4 Also known as apparent magnitude It is a star’s brightness as seen from Earth solarsystem.nasa.gov 23

Hertzprung-Russell diagram (H-R) diagram L 4 A graph of stars’ surface temperature versus their absolute brightness Astronomers use H-R diagrams to classify stars and to understand how stars change over time. solarsystem.nasa.gov 24

main sequence – L 4 A diagonal area of the H-R diagram where most of the stars are located solarsystem.nasa.gov 25

spectrograph – L 4 A device that breaks light into colors and produces an image of the resulting spectrum solarsystem.nasa.gov 26

black hole – L 5  An object with gravity so strong that nothing, not even light, can escape  Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)  Credit: NASA/ESA 27

nebula – L 5  A large cloud of gas and dust that is spread out in an immense (large) volume  Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)  Credit: NASA/ESA 28

neutron star – L 5  The remains of a supergiant explosion  Smaller and denser than white dwarfs  May be 3 times the mass of the sun  Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)  Credit: NASA/ESA 29

Protostar – L 5  The first stage of a star’s life  A contracting cloud of gas and dust with enough mass to form a star  Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)  Credit: NASA/ESA 30

pulsar – L 5  Rapidly spinning neutron stars  May spin hundreds of times per second  Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)  Credit: NASA/ESA 31

supernova – L 5  When a supergiant runs out of fuel – it can explode  The explosion blazes millions of times brighter  Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)  Credit: NASA/ESA 32

white dwarf – L 5  When a star runs out of fuel, it is the blue-white core of the star that is left behind  Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)  Credit: NASA/ESA 33

chromosphere – L 6  The middle layer of the sun’s atmosphere  solarsystem.nasa.gov 34

Convection zone – L 6  The outermost layer of the sun’s interio  Energy moves toward the sun’s surface by convection  solarsystem.nasa.gov 35

core – L 6  It is the central region of the sun  solarsystem.nasa.gov 36

corona – L 6  The outer layer of the sun’s atmosphere  It extends far into space  It gradually thins into streams of solar wind  solarsystem.nasa.gov 37

nuclear fusion – L 6  A process where hydrogen atoms join together to form helium;  Requires extremely high temperature and pressure  solarsystem.nasa.gov 38

photosphere – L 6  The inner layer of the sun’s atmosphere  solarsystem.nasa.gov 39

prominence – L 6  Huge loops of gas that link different parts of sunspot regions together  solarsystem.nasa.gov 40

radiation zone – L 6  A region of very tightly packed gas where energy moves mainly in the form of electromagnetic radiation  solarsystem.nasa.gov 41

solar flare – L 6  When loops in sunspot regions connect, it releases energy and causes gas to erupt into space  solarsystem.nasa.gov 42

solar wind – L 6  Electrically charged particles  Can enter the Earth’s atmosphere near the North and South poles – causes auroras  They can also cause magnetic storms  solarsystem.nasa.gov 43

sunspot – L 6  Areas of gas on the sun’s surface  They are cooler than the gases around them  They give off less light – so they look dark  solarsystem.nasa.gov 44