Download GSC 1580 Vocabulary/Who`s Who

GSC 1580 Vocabulary & Who’s Who
aberration: a small periodic change of apparent position in celestial bodies due to the
combined effect of the motion of light and the motion of the observer.
Adams, John: English astronomer and undergraduate of Cambridge university who spent
four years theorizing the existence of the planet Uranus but was unsuccessful at
discovering it.
annular eclipse: an eclipse in which a thin outer ring of the Sun's disk is not covered by
the smaller dark disk of the moon.
Antarctic Circle: Most northerly line in the Southern Hemisphere where 24 hours of
darkness or Sunlight is possible.
Artic Circle: Most southerly line in the Northern Hemisphere where 24 hours of darkness
or Sunlight is possible.
astronomical unit: a unit of length used in astronomy equal to the mean distance of the
earth from the sun or about 93 million miles (150 million kilometers.)
atmosphere: the gaseous envelope of a celestial body (as a planet.)
circumference: the perimeter of a circle.
Copernicus: Polish astronomer (1473-1543, full name Nicolaus Mikołaj Koyperynik) who
proposed the heliocentric system, that the stars are stationary, and that heavenly bodies
move in perfect circles and at constant speeds.
Coriolis force: an apparent force that as a result of the Earth's rotation deflects moving
objects (as projectiles or air currents) to the right in the northern hemisphere and to the
left in the southern hemisphere.
crater: the bowl-shaped depression around the orifice of a volcano OR a depression
formed by an impact (as of a meteorite.)
crescent: the moon at any stage between new moon and first quarter and between last
quarter and the succeeding new moon when less than half of the illuminated hemisphere
is visible.
day: the period of rotation of a planet (as Earth) or a moon on its axis.
density: the mass of a substance per unit of volume.
diameter: the length of a straight line through the center of an object.
Doppler effect: a change in the frequency with which waves (as of sound or light) from a
given source reach an observer when the source and the observer are in motion with
respect to each other so that the frequency increases or decreases according to the speed
at which the distance is decreasing or increasing.
eclipse: the total or partial obscuring of one celestial body by another.
ellipse: an oval. More specifically, a closed plane curve generated by a point moving in
such a way that the sum of its distances from two fixed points is constant.
epicycles: a circle in which a planet moves and which has a center that is itself carried
around at the same time on the circumference of a larger circle. These small “loops” were
proposed by Ptolemy to explain retrograde motion in the orbits of planets.
Eratosthenes: Greek astronomer (c. 276-194 B.C.) that made the best early determination
of the Earth’s size.
escape velocity: the minimum velocity that a moving body (as a rocket) must have to
escape from the gravitational field of a celestial body (as the earth) and move outward
into space.
Galileo: Italian astronomer (1564-1642, full name Galileo Galilei) who was the first
person to point a telescope toward the heavens and see the mountains and craters of the
Moon. He was the first to detect the four largest moons of Jupiter, the phases of Venus,
and Sunspots.
Galle, Johann: German astronomer who discovered the planet Uranus.
geocentric system: a universal system at which the Earth is centered. (Ptolemaic)
gibbous: seen with more than half but not all of the apparent disk illuminated.
gravity: the gravitational attraction of the mass of the Earth, the moon, or a planet for
bodies at or near its surface, OR a fundamental physical force that is responsible for
interactions which occur because of mass between particles, between aggregations of
matter (as stars and planets), and between particles (as photons) and aggregations of
matter, that is 1039 times weaker than the strong force, and that extends over infinite
distances but is dominant over macroscopic distances especially between aggregations of
matter.
heliocentric system: a universal system at which the Sun is centered. (Copernican)
Herschel: English astronomer (1738-1822, full name Sir William Herschel) who
discovered the planet Uranus on March 13, 1781.
high tide: the tide when the water is at its greatest elevation.
inferior planet: either of the planets Mercury and Venus whose orbits lie within that of
the earth.
isotope: any of two or more species of atoms of a chemical element with the same atomic
number and nearly identical chemical behavior but with differing atomic mass or mass
number and different physical properties.
jovian: Jupiter-like (from the Latin jov-, for Jupiter.)
Kepler: German astronomer (1571-1630, full name Johannes Kepler) who proposed
Kepler’s Laws. These laws proposed that the orbit of a planet is an ellipse, planets travel
faster when they near the Sun in their orbits, and that the further away from the Sun, the
slower the speed of the object.
kinetic theory of gases: a theory that the particles of a gas move in straight lines with high
average velocity, continually encounter one another and thus change their individual
velocities and directions, and cause pressure by their impact against the walls of a
container.
Leverrier, Urban: French astronomer who theorized the existence of the planet Uranus
but was unsuccessful at discovering it.
limb darkening: the “darkening” of light reflected off the matter on the outer edges of a
planet or moon.
limb: the outer edge of the apparent disk of a celestial body.
low tide: the farthest ebb of the tide.
lunar: of, relating to, or resembling the moon.
magnetic field: the portion of space near a magnetic body or a current-carrying body in
which the magnetic forces due to the body or current can be detected.
mare, maria (pl.): any of several mostly flat dark areas of considerable extent on the
surface of the moon or Mars.
mass: the property of a body that is a measure of its inertia and that is commonly taken as
a measure of the amount of material it contains and causes it to have weight in a
gravitational field.
matter: the substance of which a physical object is composed OR material substance that
occupies space, has mass, and is composed predominantly of atoms consisting of protons,
neutrons, and electrons, that constitutes the observable universe, and that is
interconvertible with energy.
microbiological planetary engineering: the concept of developing microorganisms to alter
the surface or atmosphere of an extraterrestrial planet for the purpose of making it more
hospitable to human life.
mnemonic: assisting or intended to assist memory. (ex. R.O.Y.G.B.I.V., the mnemonic
device for the major colors of the spectrum: red, orange, yellow, green, blue, indigo,
violet.)
month: a measure of time corresponding nearly to the period of the moon's revolution and
amounting to approximately 4 weeks or 30 days or 1/12 of a year.
moon: a natural satellite of a planet.
Moon: the Earth's natural satellite that shines by the Sun's reflected light, revolves about
the Earth from west to east in about 29 1/2 days with reference to the Sun or about 27 1/3
days with reference to the stars, and has a diameter of 2160 miles, a mean distance from
the Earth of about 238,900 miles, and a mass about 1/80th that of the Earth.
neap tide: a tide of minimum range occurring at the first and the third quarters of the
moon.
oblate spheroid: a sphere-like shape that is flattened or depressed at the poles.
occult, occultation: to shut off from view or exposure. (ex. Uranus’ rings were discovered
during a stellar occultation.)
orbit: a path described by one body in its revolution about another, OR one complete
revolution of a body describing such a path.
parallax: the angular difference in direction of a celestial body as measured from two
points on the Earth's orbit, OR the apparent change in the position of an object due to an
actual change in the position of the observer.
pendulum: a body suspended from a fixed point so as to swing freely to and fro under the
action of gravity and commonly used to regulate movements (as of clockwork.)
perihelion: the point in the path of a celestial body (as a planet) that is nearest to the Sun.
planet: any of the large bodies that revolve around the Sun in the solar system, OR a
similar body associated with another star.
precession: a comparatively slow gyration of the rotation axis of a spinning body about
another line intersecting it (so as to describe a cone.)
Ptolemy: Alexandrian astronomer (2nd century A.D., full name Claudius Ptolemaeus)
who proposed and extended the concept of a geocentric (Ptolemaic) system.
retrograde motion: having or being motion in a direction contrary to that of the general
motion of similar bodies and especially east to west among the stars.
revolution: the action by a celestial body of going round in an orbit or elliptical course.
Roche limit: The Roche limit is the point where a moon would be so close to its primary
planet that it would break up due to tidal forces.
rotation: the action or process of rotating on or as if on an axis or center. i.e., the Earth
rotates on an axis as it revolves around the Sun.
sidereal day: the time it takes for a planet to make one rotation in relation to the stars.
This day is 23 hours, 56 minutes and 4.099 seconds long.
solar day: the time it takes a planet to make one rotation in relation to the Sun. This is the
most familiar definition of a day, and takes 24 hours.
solar: of, derived from, relating to, or caused by the Sun.
sphere: a solid that is bounded by a surface consisting of all points at a given distance
from a point constituting its center.
spring tide: a tide of greater-than-average range around the times of new moon and full
moon.
stellar: of or relating to the stars.
sublime, sublimation: to cause to pass directly from the solid to the vapor state and
condense back to solid form.
superior orbit: a planet (as Jupiter) whose orbit lies outside that of Earth.
terraform: to make a planet more Earth-like.
terrestrial: Earth-like (from the Latin terra, for Earth.)
tide: the alternate rising and falling of the surface of the ocean and of water bodies (as
gulfs and bays) connected with the ocean that occurs usually twice a day and is the result
of differing gravitational forces exerted at different parts of the Earth by another body (as
the moon or Sun.)
total eclipse: an eclipse in which one celestial body is completely obscured by the shadow
or body of another.
Tropic of Cancer: the parallel of latitude that is approximately 23 1/2 degrees north of the
equator and that is the northernmost latitude reached by the overhead Sun.
Tropic of Capricorn: the parallel of latitude that is approximately 23 1/2 degrees south of
the equator and that is the southernmost latitude reached by the overhead Sun.
Tycho: Danish astronomer (1546-1601, full name Tycho Brahe) who provided years of
systematic and accurate observations which were vital to Kepler’s system of laws. Was
the first to observe that celestial bodies move in non-circular (elliptical) orbits.
week: An Earth term that lasts seven Earth days, possibly due to the seven “heavenly
wanderers.”
weight: the force with which a body is attracted toward the Earth or a celestial body by
gravitation and which is equal to the product of the mass and the local gravitational
acceleration.
year: the time in which a planet completes a revolution about the Sun.
Tombaugh, Clyde: American astronomer (1906-1997, full name Clyde William
Tambaugh) of the Lowell Observatory in Flagstaff, Arizona, who discovered the planet
Pluto in 1930.