click below
click below
Normal Size Small Size show me how
Astronomy Part 1
Term | Definition |
---|---|
astronomy | the science that deals with materials beyond earth's atmosphere |
geocentric | having earth as the center of the universe |
heliocentric | having the sun as the center of the universe |
retrograde motion | apparent motion of a planet to move in a direction opposite to that of other bodies within its system |
ellipse | a regular oval shape, traced by a point moving in a plane so that the sum of its distances from two other points (the foci) is constant, or resulting when a cone is cut by an oblique plane that does not intersect the base |
astronomical unit (AU) | a unit of length |
rotation | turning around is if on an axis |
revolution | the orbiting of one heavenly body around another |
precession | the slow, conical motion of the earth's axis of rotation |
perhelion | point in orbit when a planet or comet is closest to the sun |
aphelion | point in orbit when a planet or comet is furthest away from the sun |
perigee | the point in the orbit of a heavenly body, especially the moon, or man made satellite when its is closest to the earth |
apogee | the point in the orbit of a heavenly body, especially the moon, or man made satellite when it is farthest from earth |
phases of the moon | the different ways the sun casts light on the moon, change depending on where the moon is in its revolution |
solar eclipse | obscuration of the light of the sun by the intervention of the moon between it and the point on the earth |
lunar eclipse | obscuration of the light of the moon by the intervention of the earth between it and the sun |
crater | the circular or almost circular area havig a depressing floor (on the moon) |
terrestrial planet | inner planets |
jovian planet | any of the four large outer planets: saturn, jupiter, uranus, neptune |
nebula | a cloud of interstellar gas and dust |
planetesiaml | one of the small celestial bodies that according to one theory were fused together to form the planets of the solar system |
asteroid | minor planet; any of the thousands of small bodies that revolve around the sun in orbits lying in between Mars and Jupiter |
comet | a celestial body usually moving about the sun, usually in a highly eccentric orbit, consisting of a central mass surrounded by an envelope of dust and gas that may form a tail that streams away from the sun |
coma | the nebulous envelope around the nucleus of the comet |
meteoroid | any of the small bodies, often remnants of comets, traveling through space |
meteor | a meteoroid that has entered earth's atmosphere |
meteorite | a mass of stone or metal that has reached the earth from outer space; a fallen meteoroid |
electromagnetic spectrum | the entire spectrum of all kinds of electric, magnetic, and visible radiation |
photon | a quantum of electromagnetic radiation, usually considered as an elementary that is its own antiparticle and that has zero rest mass and charge and a spin of one |
spectroscopy | the science that deals with the use of the spectroscope and with spectrum analysis |
doppler effect | the shift in frequency of acoustic or electromagnetic radiation emitted by a source moving relative to an observer as percieved by the observer |
refracting telescope | an objective lens set into one end of a tube and an adjustable eyepiece or combination of lenses set into other end of tube that slides into the first and through which the object is viewed directly |
reflecting telescope | concave mirror that gathers light from object and focuses it into an adjustable eyepiece or combination of lenses through which the reflection of the object is enlarged and viewed |
radio telescope | a system consistiong of an antenna either parabolic or dipolar used to gather radio waves emitted by celestial sources and bring them to a receiver placed in focus |
hubble telescope | telescope launched into orbit around the earth to provide information about the universe in the visible, infrared, and ultraviolet ranges |
space shuttle | space vehicle |