ESC 1000 Earth Science
Chapter 21 Vocabulary
Fill in
the blanks with the word(s) that best fit the description:
1.
Aphelion – the place in the orbit of a
planet where the planet is farthest from the Sun
Astronomical unit (AU) – Average
distance from the earth to the Sun; 1.5 x 108 km or
93 x 106 miles
2.
Celestial sphere – An imaginary hollow sphere upon
which the ancients believed the stars were hung and carried around the earth
3.
Constellations – An apparent group of stars
originally names fir mythical characters. The sky is presently divided into 88
of the these groups.
4.
Declination –The angular distance north or
south of the celestial equator denoting the position of a celestial body.
5.
Ecliptic – The yearly path of the Sun
plotted against the background of the stars.
Equatorial
system – A method of locating stellar objects much like the
coordinate system used on the Earth’s surface.
Geocentric – The concept of an Earth-centered universe.
6.
Heliocentric – The view that the Sun is at the center
of the solar system.
7.
Lunar eclipse – An eclipse of the moon.
8.
Mean solar day – The average time between two
passages of the Sun across the local celestial meridian.
9.
Perihelion – The point in the orbit of a planet
where it is closest to the sun.
10.
Perturbation – The gravitational disturbance of
the orbit of one celestial body by another
Phases
of the moon – The progression of chances in the
Moon’s appearance during the month.
11.
Plane of the ecliptic - The imaginary plane that connects
Earth’s orbit with another celestial sphere
12.
Precession - A slow motion of Earth’s axis that
traces out a cone over a period of 36,000 years
Ptolemaic
system – An Earth-centered system of the universe.
Retrograde
motion – The apparent westward motion of the planets with
respect to the stars.
13.
Revolution - The motion of one body about
another, as the Earth about the sun.
14.
Right ascension – An angular distance measured
eastward along the celestial equation from the vernal equinox
15.
Rotation – The
spinning of a body such as the Earth, about its axis.
Sideral day – The period of Earth’s rotation with respect to the stars.
Sideral month – A time period based on the revolution of the Moon around the earth
with respect to the stars.
16.
Solar eclipse – An eclipse of the Sun
Synodic month
– The period of revoltion of the Moon with respect to
the Sun, or its cycle of phases.