11945299
Description
Flashcards by Jisu Nguyen, updated more than 1 year ago
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Created by Jisu Nguyen
almost 7 years ago
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| Question | Answer |
| universe | the totality of all space, time, matter, and energy |
| astronomy | the study of the universe |
| annular eclipse | solar eclipse occurring at a time when the moon is far enough away from Earth that it fails to cover the disk of the Sun completely, leaving a ring of sunlight visible around its edge |
| autumnal equinox | date on which the Sun crosses the celestial equator moving southward, occurring on or near September 22 |
| baseline | the distance between two observing locations used for the purposes of triangulation measurements. the larger the baseline, the better the resolution attainable. |
| celestial coordinates | pair of quantities-right ascension and declination-similar to longitude and latitude on Earth, used to pinpoint locations of objects on the celestial sphere |
| celestial equator | the projection of Earth's equator onto the celestial sphere |
| celestial sphere | imaginary sphere surrounding Earth to which all objects in the sky were once considered to be attached |
| constellation | a human grouping of stars in the night sky into a recognizable pattern |
| cosmic distance scale | collection of indirect distance-measurement techniques that astronomers use to measure distances in the universe |
| declination | celestial coordinate used to measure latitude above or below the celestial equator on the celestial sphere |
| diurnal motion | apparent daily motion of the stars caused by Earth's rotation |
| ecliptic | the apparent path of the Sun, relative to the stars on the celestial sphere, over the course of a year |
| eclipse | event during which one body passes in front of another, so that the light from the occulted body is blocked |
| full moon | phase of the moon in which it appears as a complete circular disk in the sky |
| galaxy | gravitationally bound collection of a large number of stars |
| lunar eclipse | celestial event during which the moon passes through the shadow of the earth, temporarily darkening its surface |
| lunar phase | the appearance of the moon at different points along its orbit |
| new moon | phase of the moon during which none of the lunar disk is visible |
| north celestial pole | point on the celestial sphere directly above Earth's North Pole |
| parallax | the apparent motion of a relatively close object with respect to a more distant background as the location of the observer changes |
| partial eclipse | celestial event during which only a part of the occulted body is blocked from view |
| penumbra | portion of the shadow cast by an eclipsing object in which the eclipse is seen as partial. |
| phase | appearance of the sunlit face of the moon at different points along its orbit, as seen from Earth |
| planet | a celestial body moving in an elliptical orbit around a star |
| precession | the slow change in direction of the rotation axis of a spinning object, caused by some external gravitational influence |
| quarter moon | lunar phase in which the moon appears as a half disk |
| revolution | orbital motion of one body about another, such as Earth about the Sun |
| right ascension | celestial coordinate used to measure longitude on the celestial sphere. the zero point is the position of the Sun at the vernal equinox. |
| science | a step-by-step process for investigating the physical world based on natural laws and observed phenomena |
| scientific method | the set of rules used to guide science, based on the idea that scientific "laws" be continually tested and modified or replaced if found inadequate |
| seasons | changes in average temperature and length of day that result from the tilt of Earth's (or any planet's) axis with respect to the plane of its orbit |
| sidereal day | the time needed between successive risings of a given star |
| sidereal month | time required for the moon to complete one trip around the celestial sphere |
| sidereal year | the time required for the constellations to complete one cycle around the sky and return to their starting points, as seen from a given point on Earth. Earth's orbital period around the Sun is one sidereal year. |
| solar day | the period of time between the instant when the sun is directly overhead to the next time it is directly overhead |
| solar eclipse | celestial event during which the new moon passes directly between the Sun and Earth, temporarily blocking the Sun's light |
| south celestial pole | point on the celestial sphere directly above Earth's South Pole |
| star | a glowing ball of gas held together by its own gravity and powered by nuclear fusion in its core |
| summer solstice | point on the ecliptic where the Sun is at its northernmost point above the celestial equator, occurring on or near June 21 |
| synodic month | time required for the moon to complete a full cycle of phases |
| theoretical model | an attempt to construct a mathematical explanation of a physical process or phenomenon within the assumptions and confines of a given theory. in addition to providing an explanation of the observed facts, the model generally also makes new predictions that can be tested by further observation or experimentation |
| theory | a framework of ideas and assumptions used to explain some set of observations and make predictions about the real world |
| total eclipse | celestial event during which one body is completely blocked by another |
| triangulation | method of determining distance based on the principles of geometry. a distant object is sighted from two well-separated locations. the distance between the two locations and the angle between the line joining them and the line to the distant object are all that are necessary to ascertain the object's distance |
| tropical year | the time interval between one vernal equinox and the next |
| umbra | central region of the shadow cast by an eclipsing body |
| vernal equinox | date on which the Sun crosses the celestial equator moving northward, occurring on or near March 21 |
| winter solstice | point on the ecliptic where the Sun is at its southernmost point below the celestial equator, occurring on or near December 21 |
| zodiac | the 12 constellations on the celestial sphere through which the Sun appears to pass during the course of a year |
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