4: Earth, Moon, and Sky Flashcards
circle of latitude above South Pole at 67° S - 24-hour period of darkness during summer solstice, sunlight during winter solstice
Antarctic Circle
the angular distance north or south of the celestial equator
declination
alternate rising and falling of sea level caused by the difference in the strength of the Moon’s gravitational pull on different parts of Earth
tides
Earth’s rotation period as defined by the position of the Sun in the sky; the time between successive passages of the Sun through the meridian
solar day
arbitrary line on the surface of Earth near longitude 180° across which the date changes by one day
International Date Line
town designated as the Prime Meridian of the world, with a longitude of 0 degrees
Greenwich, England
the period of the Moon’s revolution about Earth measured with respect to the stars
sidereal month
latitude where the Sun appears directly overhead (at zenith) at noon during the summer solstice (23° N)
Tropic of Cancer
the time interval in which the phases repeat - say, from full to full phase
solar month
an eclipse of the Sun by the Moon, caused by the passage of the Moon in front of the Sun - can occur only at the time of the new moon
solar eclipse
the coordinate for measuring the east-west positions of celestial bodies; the angle measured eastward along the celestial equator from the vernal equinox to the hour circle passing through a body
right ascension (RA)
latitude where the Sun appears directly overhead (at zenith) at noon during the winter solstice (23° S)
Tropic of Capricorn
an eclipse of the Moon, in which the Moon moves into the shadow of Earth - can occur only at the time of full moon
lunar eclipse
a circle on the surface of a sphere that is the curve of intersection of the sphere with a plane passing through its center
great circle
larger-than-average tides created when Sun and Moon are lined up with one another (new or full Moon)
spring tides
circle of latitude below North Pole at 67° N - 24-hour period of sunlight during summer solstice, darkness during winter solstice
Arctic Circle
Earth’s rotation period as defined by the positions of the stars in the sky; the time between successive passages of the same star through the meridian
sidereal day
time as measured by the position of the Sun in the sky (the time that would be indicated by a sundial)
apparent solar time
lower-than-average tides created when Moon is at a right angle to the Sun’s direction
neap tides
June 21 - day in which the Sun shines down most directly upon the Northern Hemisphere (longest day)
summer solstice
when a body (for example, the Moon) rotates at the same rate that it revolves around another body
synchronous rotation
December 21 - day in which Northern Hemisphere receives the least sunlight (shortest day)
winter solstice
time based on the rotation of Earth - passes at a constant rate, unlike apparent solar time
mean solar time
the different appearance of light and dark on the Moon as seen from Earth during its monthly cycle, from new moon to full moon and back to new moon
phases of the Moon
point in the sky where ecliptic (Sun’s path) crosses the celestial equator - starting point for calculating right ascension
vernal equinox
a great circle on the terrestrial or celestial sphere that passes through the poles
meridian
