The Essential Cosmic Perspective - Chapter 2 Flashcards

3714419343	constellation	a region of the sky with well-defined borders	0
3714421094	celestial sphere	the illusion that all stars lie on the edge of a sphere around Earth that occurs because we lack depth perception	1
3714425267	north celestial pole	the point directly above Earth's North Pole	2
3714431491	south celestial pole	the point directly above Earth's South Pole	3
3714432914	celestial equator	a projection of Earth's equator into space, which makes a complete circle around the celestial sphere	4
3714435533	ecliptic	the path the Sun follows as it appears to circle around the celestial sphere once each year	5
3714438880	local sky	the sky as seen from where you happen to be standing	6
3714440575	horizon	the boundary between Earth and the sky	7
3714442304	zenith	the point directly overhead in the sky	8
3714443891	meridian	an imaginary half-circle stretching from the horizon due south, through the zenith, to the horizon due north	9
3714447356	direction (local sky)	one of the two coordinates needed to pinpoint an object in the local sky	10
3714449621	altitude	the angular distance between the horizon and an object in the sky	11
3714451180	angular size (or angular distance)	a measure of the angle formed by extending imaginary lines outward from our eyes to span an object (or the space between two objects)	12
3714451870	arcminute	1/60 of 1 degree	13
3714451871	circumpolar star	a star that always remains above the horizon for a particular latitude	14
3714451872	latitude	the angular north-south distance between Earth's equator and a location on Earth's surface	15
3714452803	longitude	the angular east-west distance between the prime meridian and a location on Earth's surface	16
3714454158	prime meridian	the meridian of longitude that passes through Greenwich, England; defined to be longitude 0 degrees	17
3714454159	zodiac	the constellations on the celestial sphere through which the ecliptic passes	18
3718896318	June solstice	the moment when the Northern Hemisphere is tipped most directly toward the Sun and receives the most direct sunlight	19
3718896319	December solstice	the moment when the Northern Hemisphere receives the least direct sunlight	20
3718896989	March equinox	the moment when the Northern Hemisphere goes from being tipped slightly away from the Sun to being tipped slightly toward the Sun	21
3718897943	September equinox	the moment in when the Northern Hemisphere first starts to be tipped away from the Sun	22
3718897944	precession	the gradual wobble of the axis of a rotating object around a vertical line	23
3718898996	lunar phases	the state determined by the portion of the visible face of the Moon that is illuminated by sunlight; cycles through waxing crescent, first-quarter, waxing gibbous, full, waning gibbous, third-quarter, waning crescent, and back to new	24
3718900954	synchronous rotation	the rotation of an object that always shows the same face to an object that it is orbiting because its rotation period and orbital period are equal	25
3718900955	eclipse	an event in which one astronomical object casts a shadow on another or crosses our line of sight to the other object	26
3718902024	lunar eclipse	an event that occurs when the Moon passes through Earth's shadow, which can occur only at full moon	27
3718902025	solar eclipse	an event that occurs when the Moon's shadow falls on Earth, which can occur only at a new moon	28
3718902026	nodes	the two points in the Moon's orbit where it crosses the ecliptic plane	29
3718902027	umbra	the dark central region of a shadow	30
3718904174	penumbra	the lighter, outlying regions of a shadow	31
3718904175	total lunar eclipse	a lunar eclipse in which the Moon becomes fully covered by Earth's umbral shadow	32
3718904812	partial lunar eclipse	a lunar eclipse during which the Moon becomes only partially covered by Earth's umbral shadow	33
3718904813	penumbral lunar eclipse	a lunar eclipse during which the Moon passes only within Earth's penumbral shadow and does not fall within the umbra	34
3718906356	totality	the portion of a total lunar eclipse during which the Moon is fully within Earth's umbral shadow or a total solar eclipse during which the Sun's disk is fully blocked by the Moon	35
3718906357	total solar eclipse	a solar eclipse during which the Sun becomes fully blocked by the disk of the Moon	36
3718907763	annular eclipse	a solar eclipse during which the Moon is directly in front of the Sun but its angular size is not large enough to fully block the Sun; thus, a ring of sunlight is still visible around the Moon's disk	37
3718907764	partial solar eclipse	a solar eclipse during which the Sun becomes only partially blocked by the disk of the Moon	38
3718910329	saros cycle	the period over which the basic pattern of eclipses repeats, which is about 18 years and 11 1/3 days	39
3718910889	apparent retrograde motion	the apparent motion of a planet, as viewed from Earth, during the period of a few weeks or months when it moves westward relative to the stars in our sky	40
3718912901	stellar parallax	the apparent shift in the position of a nearby star (relative to distant objects) that occurs as we view the star from different positions in Earth's orbit of the Sun each year	41