Science 8th Astronomy Chapter 4
Terms
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- quasar
- an enormously bright, distant galaxy with a giant black hole at its center
- electromagnetic radiation
- energy that travels through space in the form of waves
- characteristics used to classify stars include:
- color, temperature, size, composition, and brightness
- supernova
- the brilliant explosion of a dying supergiant star
- dark matter
- matter that does not give off electromagnetic radiation but is quite abundant in the universe
- scientific notation
- a mathematical method of writing numbers using powers of ten
- convex lens
- a piece of transparent glass curved so that the middle is thicker than the edges
- nebula
- a large cloud of gas and dust in space, spread out in an immense volume
- galaxy
- a huge group of single stars, star systems, star clusters, dust, and gas bound together by gravity
- eclipsing binary
- a binary star system in which one star peridically blocks the light from the other
- solar nebula
- a large cloud of gas and dust, such as one that formed our solar system
- reflecting telescope
- a telescope that uses a curved mirror to collect and focus light
- white dwarf
- the blue-white hot core of a star that is left behind after its outer layers have expanded and drifted out into space
- apparent brightness
- the brightness of a star as seen from earth
- spiral galaxy
- a galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern
- absolute brightness
- the brightness a star would have if it were at a standard distance from the earth
- after a star runs out of fuel it becomes
- a white dwarf, a neutron star, or a black hole
- planetesimal
- one of the small asteroid-like bodies that formed the building blocks of the planets
- universe
- all of space and everything in it
- spectrograph
- an instrument that separates light into colors and makes an image of the resulting
- The electromagnetic spectrum includes the entrie range of:
- radio waves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays
- visible light
- electromagnetic radiadtion that can be seen with the unaided eye
- irregular galaxy
- a galaxy that does not have a regular shape
- a star is born when
- the contracting gas and dust from a nebula become so dense and hot that nuclear fusion starts
- refracting telescope
- a telescope that uses convex lenses to gather and focus light
- neutron star
- the small, dense remains of a high-mass star after a supernova
- dark energy
- a mysterious force tha tappears to be causing the expansion of the universe to accelerate
- Hubble's law
- the observation that the farther away a galaxy is, the faster it is moving away
- parallax
- the apparent change in position of an object when seen from different places
- telescope
- a device built to observe distant objects by making them appear closer
- optical telescope
- a telescope that uses lenses or mirrors to collect and focus visible light
- binary star
- a star system with two stars
- observatory
- a building that contains one or more telescope
- Hertzsprung-Russell diagram
- a graph relating the surface temperatures and absolute brightness of stars
- big bang
- the initial explosion that resulted in the formation and expansion of the universe
- constellation
- an imaginary pattern of stars in the sky
- globular cluster
- a large, round, densely-packed grouping of older stars
- open cluster
- a star cluster that has a loose, disorganized appearance and contains no more than a few thousand stars
- Many large observatories are located:
- on mountaintops ir in space
- protostar
- a contracting cloud of gas and dust with enough mas to form a star
- spectrum
- the range of wavelengths of electromagnetic waves
- cosmic background radiation
- the electromagnetic radiation left over fro mthe big bang
- main sequence
- a diagonal area on an H-R diagram that includes more than 90 percent of all stars
- the brightness of a star depends on
- its size and temperature
- light-year
- the distance that light travels in one year, about 9.5 million million kilometers
- radio telescope
- a device used to detect radio waves from objects in space
- wavelength
- the distance between the crest of one wave and the crest of the next wave