Download Chapter 1 Starts and Galaxies

Chapter 1 Stars and Galaxies
Binary star- member of a double star system
Constellation- group of stars that form a pattern
Nova- star that suddenly increases in brightness in just a few hours or days
Nebula- massive cloud of dust and gas between the stars
Galaxy- huge collection of stars
Spiral Galaxy- galaxy that is shaped like a pin wheel; one of the three types of galaxies
Elliptical galaxy- galaxy that may vary in shape from nearly spherical to flat; one of three
types of galaxies
Spectroscope- instrument that breaks up the light from a distant star into its characteristic
colors
Spectrum- band of colors formed when light passes through a prism
Red shift- shift toward the red end of the spectrum of a star that is moving away from the
Earth
Doppler effect- apparent change in the wavelength of light that occurs when an object is
moving toward or away from the Earth
Big-bang theory- theory that states that the universe began to expand with the explosion
of concentrated matter and energy and has been expanding ever since
Gravity- force of attraction between objects
Quasar- quasi-stellar radio source; distant object that gives off mainly radio waves and Xrays
Giant star- star with a diameter about 10 to 100 times as large as the sun
Supergiant star- star with a diameter up to 1000 times the diameter of the sun; largest of
all stars
White dwarf- small dense star
Neutron star- smallest of all stars
Apparent magnitude- brightness of a star as it appears from Earth
Absolute magnitude- amount of light a star actually gives off.
Hertzsprung-Russell diagram- chart that shows the relationship between the absolute
magnitude and the surface temperature of stars; also called H-R diagram
Main-sequence star- star that falls in an area from the upper left corner to the lower right
corner of the H-R diagram
Parallax- apparent change in the position of a star in the sky due to the change in Earth’s
position as the Earth moves around the sun
Nuclear fusion- process by which hydrogen atoms are fused, or joined together, to form
helium atoms
Corona- outermost layer of the sun’s atmosphere
Chromosphere- middle layer of the sun’s atmosphere
Photosphere- innermost layer of the sun’s atmosphere
Core- center of the sun
Prominence- violent storm on the sun that can be seen from Earth as a huge bright arch or
loop of hot gas
Solar flare- storm on the sun that shows up as a bright burst of light on the sun’s surface
Solar wind- continuous stream of high-energy particles released into space in all
directions from the sun’s corona
Sunspot- dark area on the sun’s surface
Axis- imaginary vertical line through the center of body around which the body
rotates, or spins
Protostar- new star
Supernova- tremendous explosion in which a star breaks apart, releasing energy and
newly formed elements
Pulsar- neutron star that gives off pulses of radio waves
Black hole- core of a super-massive star that remains after a supernova; the gravity of the
core is so strong that not even light can escape