Download Chapter 1 Vocabulary – The Puzzled of Matter

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Vocabulary – Exploring the Universe
Sun’s Interior
 Core – the central region of the sun where nuclear fusion occurs
 Radiation Zone – a region of closely-packed plasma outside the core of the sun, where energy is
transferred by the absorption and reradiation of light
 Convection Zone – the region inside the sun where thermal energy is transferred outward mainly by
convection currents
Sun’s Atmosphere
 Photosphere – the thin innermost layer of the sun’s atmosphere, which is the visible surface of the sun
 Chromosphere – the middle layer of the sun’s atmosphere, just outside the photosphere
 Corona – the outermost layer of the sun’s atmosphere
Solar Wind – a stream of electrically charged particles that flow from the sun outward through the solar
system
Features of the Sun’s Atmosphere
 Sunspots – an area of gas in the sun’s photosphere that is cooler than the surrounding gases
 Prominences – huge loops of gas that erupt from sunspot regions and extend upward from the
photosphere into the chromosphere and sometimes into the corona
 Solar Flare – a dramatic eruption on the sun’s surface, usually near sunspots, that produces X-rays
and sends charged particles into space at speeds of 1000 km/s or more
Star – a large, glowing ball of gas in space that generates energy through nuclear fusion in its core
Light-year – the distance that light travels in a vacuum in a year, about 9.5 trillion kilometers
Parallax – an apparent change in position of an object with respect to a distant background when viewed
from different locations
Properties of Stars
 Color and Temperature
 Brightness
 Size and Mass
 Composition
Apparent Brightness – the brightness of a star as it appears from Earth
Absolute Brightness – a description of how bright a star really is; a characteristic property of a star that
does not depend on the star’s distance from Earth
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Classification of Stars
 Supergiants – a very large, massive, bright star ranging in size from 100 - 1000 times the dia. of the sun
 Giants – a large, massive, bright star that is somewhat smaller and fainter than a supergiant
 Main Sequence – a diagonal band on the H-R diagram, which represents about 90% of all stars
 White Dwarf – a small, dense, but dim remains of a low- or medium-mass star
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Absorption Lines – a set of dark lines that show frequencies at which light has been absorbed from a
star’s bright spectrum
H-R Diagram – the Hertxsprung-Russell diagram, a graph of the surface temperature versus absolute
brightness of a sample of stars
Star Life Cycle
Nebula – a large cloud of gas and dust spread out over a large volume of space
Protostar – a contracting nebula with enough mass to form a star
Planetary Nebula – a glowing cloud of gas surrounding a dying low-mass star
Supernova – an enormous explosion in which the byproducts of a supergiant star’s lifetime of fusion are
flung into space
Neutron Star – the dense core left after a high-mass star has exploded as a supernova
Pulsar – a spinning neutron star that appears to give off strong pulses of radio waves
Black Hole – an object whose surface gravity is so great that no even electromagnetic waves can escape
from it
Constellation – a group of stars that appears to from a pattern as seen from Earth
Star System – a group of two or more stars held together by gravity
Binary Star – a star system with two stars that revolve around each other
3 types of Star Clusters
1. Open cluster – has disorganized or loose appearance and contains no more than a few thousand stars
that are well spread out.
2. Associations – are temporary groupings of bright, young stars. In time
3. Globular Cluster – a large spherical-shaped group of older stars that usually lacks sufficient amounts
of gas and dust to form new stars
Galaxy – a huge group of stars, star systems, star clusters, dust, and gas bound together by gravity
Types of Galaxies
1. Spiral Galaxies – a galaxy like the Milky Way with a bulge of stars at the center and arms extending
outward like a pinwheel
2. Barred-spiral Galaxies – a spiral galaxy in which spiral arms extend outward from a bar running
through the center of the galaxy
3. Elliptical Galaxies – spherical or oval-shaped galaxies with no trace of spiral arms and very little gas
or dust between stars
4. Irregular Galaxies – a galaxy with a disorganized appearance
Quasars – enormously bright center of a distant young galaxy
Red Shift – a shift toward the red wavelengths of light from stars or galaxies moving away from Earth
Hubble’s Law – the direct variation of the speed at which a galaxy is moving away from Earth with its
distance from Earth
Big Bang Theory – the theory of the beginning of the universe began in an instant, billions of years ago,
in an enormous explosion
Dark Matter – matter that does not emit radiation that astronomers can detect
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