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18 terms

Science Ch 15 1&2

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Electromagnetic radiation
energy that travels through space in the form of waves
Visible light
electromagnetic radiation that can be seen with the unaided eye
Wavelength
The distance between crests of waves, such as those of the electromagnetic spectrum.
Spectrum
the range of wavelengths of electromagnetic waves
Optical telescope
a telescope that uses lenses or mirrors to collect and focus visible light
Refracting telescope
a telescope that uses a curved mirror to collect and focus light
Convex lens
a piece of transparent glass curved so that the middle is thicker than the edges
Reflecting telescope
a telescope that uses a curved mirror to collect and focus light
Radio telescope
A device used to detect radio waves from objects in space
Constellation
An imaginary pattern of stars in the sky
Spectograph
an instrument that separates light into colors and makes an image of the resulting spectrum
Apparent brightness
The brightness of a star as seen from Earth.
Absolute brightness
the brightness a star would have if it were at a standard distance from earth
Light-Year
light distance travels in one year (9.5 trillion km)
Parallax
the apparent change in position of an object when seen from different places
Hertzsprung-Russell diagram
a graph relating the surface temperatures and absolute brightnesses of stars
Main sequence
A diagonal area on an H-R diagram that includes more than 90 percent of all stars
Observatory
a building that contains one or more telescopes