Chapter 0 Terms Flashcards
Planet
One of eight major bodies that orbit the Sun, visible to us by reflected sunlight.
Star
A glowing ball of gas held together by its own gravity and powered by nuclear fusion in its core.
Galaxy
Gravitational bound collection of a large number of stars. The Sun is a star in the Milky War Galaxy.
Universe
The Totality of all space, time, matter, and energy
Astronomy
Branch of science dedicated to the study of everything in the universe that lies above Earth’s atmosphere.
Constellation
A human grouping of stars in the night sky into a recognizable pattern.
Celestial sphere
Imaginary sphere surrounding Earth to which all objects in the sky were once considered to be attached.
Rotation
Spinning motion of a body about an axis
north celestial pole
Point on the Celestial sphere directly above Earth’s North Pole
South celestial pole
Point on the celestial sphere directly above Earth’s South Pole.
Celestial equator
The projection of Earth’s equator onto the celestial sphere
celestial coordinates
Pair of qualities-right ascension and declination-similar to longitude and latitude on Earth, used to pinpoint locations of objects on the celestial sphere
Declination
Celestial coordinate used to measure latitude above or below the celestial equator on the celestial sphere.
Right ascension
Celestial coordinate used to measure longitude on the celestial sphere. The zero point is the position of the Sun at the vernal equinox.
Solar day
The period of time between the instant when the Sun is directly overhead (i.e., noon) to the next time it is directly overhead.
Diurnal motion
Apparent daily motion of the stars caused by Earth’s rotation.
Sidereal Day
The time needed between successive risings of a given star.
Ecliptic
The apparent path of the Sun, relative to the stars on the celestial sphere, over the course of a year.
Phase
Appearance of the sunlit face of the Moon at different points along its orbit, as seen from Earth.
New Moon
Phase of the moon during which none of the lunar disk is visible.
Quarter moon
Lunar phase in which the Moon appears as a half disk.
Full moon
Phase of the Moon in which it appears as a complete circular disk in the sky
Sidereal
Time required for the Moon to complete one trip around the celestial sphere
Synodic month
Time required for the Moon to complete a full cycle of phases.
Eclipse
Event during which one body passes in front of another, so that the light from the occulted body is blocked
Lunar eclipse
Celestial event during which the moon passes through the shadow of Earth, temporarily darkening its surface.
Partial eclipse
Celestial event during which only a part of the occulted body is blocked from the view
Total eclipse
Celestial event during which one body is completely blocked from view by another
Solar eclipse
Celestial event during which the new Moon passes directly between Earth and the Sun, temporarily blocking the Sun’s light.
Umbra
Central region of the shadow cast by an eclipsing body. The central region of a sunspot, which is its darkest and coolest part
Penumbra
Portion of the shadow cast by an eclipsing object in which the eclipse is seen as partial. The outer region of a sunspot, surrounding the umbra, which is not as dark and not as cool as the central region.
Annular eclipse
Solar eclipse occurring at a time when the Moon is far enough away from Earth that it fails to cover the sun completely, leaving a ring of sunlight visible around its edge.
Triangulation
Method of determining distance based on the principles of geometry. A distance between the two locations and the angle between the line joining them and the line joining them and the line to the distant object are all that are necessary to ascertain the object’s distance.
Cosmic distance scale
Collection of indirect distance-measurement techniques that astronomers use to measure distances in the universe.
Baseline
The distance between two observing locations used for the purposes of triangulation measurements. The larger the baseline, the better the resolution attainable.
Parallax
The apparent motion of a relatively close object with respect to a more distant background as the location of the observer changes.
Science
A step-by-step process for investigation the physical world based on natural laws and observed phenomena
Theory
A framework of ideas and assumptions used to explain some set of observations and make predictions about the real world.
Theoretical model
An attempt to construct a mathematical explanation of a physical process or phenomenal within the assumptions and confines of a given theory. In addition to providing an explanation of the observed facts, the model generally also makes new predictions that can be tested by further observation or experimentation.
Scientific method
The set of rules used to guide science, based on the idea that scientific “laws” be continually tested and modified or replaced if found inadequate.
