term 4 science - our place in space

what is the celestial sphere?

a model of the sky that appears like a dome overhead, to which the stars are fixed

what is a constellation?

a group of fixed starts with a definite name

what is a day?

one rotation of earth on its axis

what is an eclipse?

an interception of the light of one celestial body by another

what is the ecliptic?

the path of the sun through the zodiac

what is an equinox?

a day in which daytime and nighttime are approximately equal in length

what is an orbit?

the path of an object through space

what is latitude?

the distance in degrees north or south of the equator

what is longitude?

the distance in degrees east or west of the prime meridian

what is a revolution?

the orbit of one object around another (or around a point in space)

what is a rotation?

the spin of an object around its own axis

what is a sidereal month?

the time taken for the moon to complete one full revolution around earth with respect to the stars

what is a solstice?

a day in which the daytime (summer solstice) or nighttime (winter solstice) is the longest of the year

what is a synodic month?

the time taken for the moon to complete one cycle of its phases

what is waxing?

the change in the moon’s appearance between new moon and the following full moon

what is waning?

the change in the moon’s appearance between full moon and the following new moon

what is a year?

one revolution of earth around the sun

what are the labelled lines described as in this image?

latitude

what are the labelled lines described as in this image?

longitude

what is the red labelled line described as in this image?

equator

what is the red labelled line described as in this image?

prime meridian

what is the imaginary sphere surrounding earth that appears like a dome overhead, as shown in the image?

celestial sphere

what is the point in the sky directly above the earth’s north pole on the celestial equator, indicated by the yellow line in the image?

north celestial pole

what is the point in the sky directly above the earth’s south pole on the celestial equator, indicated by the yellow line in the image?

south celestial pole

what is the imaginary circle on the celestial sphere that is the projection of earth’s equator, indicated by the orange line in the image?

celestial equator

what is azimuth?

an angle on the horizon, measured clockwise from north

what is the azimuth of north?

0°

what is the azimuth of east?

90°

what is the azimuth of south?

180°

what is the azimuth of west?

270°

what is elevation?

the angle of an object above the horizon

what are the elevation angles for the horizon and zenith?

horizon - 0°

zenith - 90°

what is zenith?

the point on the celestial sphere directly above an observer’s head

what is nadir?

the point on the celestial sphere directly below an observer’s feet

if someone says a star has an azimuth of 135° and an elevation of 40°, what does that mean?

the star is southeast and 40 degrees above the horizon

if someone says a star has an elevation of 90°, what does that mean?

the star is at the observer’s zenith

if someone says an object has an elevation of -90°, what does that mean?

the object is at the observer’s nadir

what is the difference between revolution and rotation?

rotation: the spin of an object around its own axis, takes about 24 hours (one day), and causes day and night

revolution: the orbit of one object around another, takes about 365.25 days (one year), and, along with the earths tilt of 23.5°, causes seasons and other yearly changes.

what is rotation?

the spin of an object around its own axis

what is revolution?

the orbit of one object around another

how long does earth take to complete one rotation?

about 24 hours (one day)

how long does earth take to complete one revolution?

about 365.25 days (one year)

what does earth’s rotation cause?

day and night

what does earth’s revolution, as well as its tilt, cause?

the four seasons

what is earth’s axis?

an imaginary line running through the north and south poles that earth rotates around

earth spins on its own axis. is this rotation or revolution?

rotation

earth travels around the sun. is this rotation or revolution?

revolution

a motorcycle is in a stunt cage, as shown in the image. is this rotation or revolution?

revolution

a revolving door is pushed. is this rotation or revolution?

rotation

the second hand of a clock moves after every minute. is this an example of rotation or revolution?

rotation

why do we experience day and night?

because of earth’s rotation on its axis. the side of the earth facing towards the sun experiences day, whereas, the side of the earth facing away experiences night.