Astronomy Midterm 1

malanee1134's version from 2016-02-08 07:20

Section 1

Question Answer
asterismlocally recognized group of stars
constellationrecognized pattern of stars that makes a picture
angular size/diameterthe apparent diameter of a planet or other celestial object measured by the angle that it subtends at the point of observation
angular separationthe angular separation between two objects as perceived by an observer
arc minutea unit of angular distance equal to a 60th of a degree
arc seconda 60th part of a minute of arc
altitudethe height of an object or point in relation to sea level or ground level
azimuthangle between the zenith and the star

Section 2

Question Answer
polarisnothern star
circumpolar constellationnever sets, visible all year, located near n. star
seasonal constellationsrise and set, seen at different times of the year- closer to horizon=shorter distance travelled
latitudemeasured north/south of equator
longitudemeasured east/west of equator
meridiandivides the sky in half
zenithpoint directly above the observer in the sky
nadirpoint on the celestial sphere directly below the observer, diametrically opposite the zenit
cardinal directionsN/E/S/W
AMante meridian
PMpost meridian
north polepost in northern hemisphere

Section 3

Question Answer
celestial sphereimaginary sphere where all celestial bodies lie around
north/south celestial polespoint on the celestial sphere that is directly above the poles
celestial equatorline that goes alone Earth's equator
ecliptic circle on the celestial sphere representing the sun's apparent path during the year
zodiacset of constellations that lie on the ecliptic
nodesintersection of the orbit plane of some celestial body with the plane of the ecliptic in the celestial sphere
precessionas Earth spins on its axis, it wobbles
nutationslight nodding on Earth's axis

Section 4

Question Answer
right ascensionmeasured along celestial equator
declinationmeasured north and south of celestial equator
revolvemotion of a body around another body
annual motionmotion of the earth in its orbit round the sun (one revolution is a year long)
solar day(s. time)- time between meridian crossings of the sun (24 hr)
sidereal day(s. time)- star time, 4 minutes shorter than solar day
solsticewhen the sun reaches its highest or lowest point in the sky at noon, marked by the longest and shortest days (at a node)
eqinoxsun crosses the celestial equator, when day and night are of equal length
Tropic of Cancer23° north of the equator
Tropic of Capricorn23° south of the equator
Arctic Circlesouthernmost latitude in the Northern Hemisphere at which the sun can remain continuously above or below the horizon for 24 hours

Section 5

Question Answer
waxingmoon moves away from the sun, right side lit (new -> full)
waningmoon moves toward the sun, left side lit (full -> new)
crescentcurved sickle shape of the waxing or waning moon
gibboushaving the observable illuminated part greater than a semicircle and less than a circle
fullmoon is completely lit
newmoon is invisible
Lunathe mooooon
synodic periodcomplete cycle (new moon to new moon)
sidereal periodtrue orbital perion of the moon
monthsynodic period (30 days)

Section 6

Question Answer
lunar eclipseoccurs when the moon moves into the earth's shadow
solar eclipseoccurs when the moon moves in front of the sun
eclipse seasononly times during a year eclipses can occur, due to the 5° inclination of the moon's orbit
nodetwo diametrically opposite points at which the orbit of a planet intersects the ecliptic
umbrafully shaded inner region of a shadow cast by an opaque object, esp. the area on the earth or moon experiencing the total phase of an eclipse
penumbrapartially shaded outer region of the shadow cast by an opaque object
eclipse pathpath of the shadow of the moon
retrograde motioncounterclockwise motion (natural orbit) of inferior planets
prograde (direct) motionclockwise motion of orbit
elongationangular separation of between a planet and the sun
transitoccurs when one celestial body appears to move across the face of another celestial body

Section 7

Question Answer
epicyclemini orbit

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