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the science words for chapter 4 astronomy on stars


device that makes distant objects appear to be closer

electromagnetic radiation

energy that can travel through space in the form of waves

visible light

light you can see


the distance between the crest of one wave and the crest of the next wave


a range of different colors with different wave lengths that you see coming out of a prism with light shone through it

optical telescope

a telescope that uses lenses or mirrors to collect and focus visible light

refracting telescope

uses convex lenses to gather and focus light

convex lens

piece of transparent glass curved so that the middle is thicker than the edges

reflecting telescope

uses a curved mirror to collect and focus light

radio telescope

devices used to detect radio waves from objects in space


building that contains one more telescopes


imaginary patterns of stars


device that breaks light into colors and produces an image of the resulting spectrum

apparent brightness

a star's brightness seen from earth

absolute brightness

a star's brightness the star would have if it were at a standard distance from earth


distance that light travels in one year


apparent change in position of an object when you look at it from different places

Hertzsprung-Russell Diagram

the graph astronomers made to find out if the temperature and absolute brightness of a star are related

main sequence

where most of the stars in the H-R diagram are, the diagonal area


large cloud of gas and dust spread out in an immense volume


contracting cloud of gas and dust with enough mass to form a star

white dwarf

blue-white core of the star that is left behind that cools


the explosion when a star runs out of fuel

neutron star

remains of high-mass stars


spinning neutron stars, short for pulsating radio sources

black hole

an object with gravity so strong that nothing, not even light can escape

binary star

star systems that have two stars

eclipsing binary

system in which one star periodically blocks the light from another

open cluster

have a loose, disorganized appearance and contain no more than a few thousand stars

globular cluster

large groupings of older stars


huge group of single stars, star systems, star clusters, dust, and gas bound together by gravity

spiral galaxy

galaxy with a bulge in the middle and arms that spiral outward like pinwheels

elliptical galaxy

galaxies that look like round or flattened balls

irregular galaxy

galaxies without regular shapes


active young galaxies with giant black holes in the middle


all of space and everything in it

scientific notation

uses powers of ten to write very large or very small numbers in shorter form

big bang

what the universe exploding is called

Hubble's Law

states that the father away a galaxy is, the faster it is moving away from us

cosmic background radiation

leftover thermal energy from the big bang

solar nebula

a large cloud of gas and dust such as the one that formed solar system


small asteroid like bodies

dark matter

matter that does not give off electromagnetic radiation

dark energy

a mysterious new force that astronomers infer is causing the expansion of the universe to accelerate

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