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BJU Space/Earth - 3
BJU - Space and Earth Science - Chapter 3
| Term | Definition |
|---|---|
| A small object or region in space with gravity so intense that it is believed that matter, energy, and even light cannot escape from within its boundaries. | black hole |
| A compact reflector telescope design that is easier to use. Its large concave mirror reflects light to a convex mirror fixed in the center near the front of the tube. | Cassegrinian reflector |
| The projection of the earth's equator onto the celestial sphere; position of 0 degrees declination. | celestial equator |
| A type of star that changes in brightness regularly, apparently because it expands and contracts on a regular basis. | Cepheid variable |
| A telescope that uses both a primary mirror and a large objective corrective lens as the main light-gathering elements of the telescope. | composite telescope |
| Two or more lenses made of different kinds of glass mounted together to correct for chromatic aberration. | compound lens |
| In ancient times, a named pattern of stars that represented famous characters, animals, or familiar objects. In modern times, it is an area of the sky marked off by segments of celestial latitude and longitude. | constellation |
| A set of 2 numbers (x value, y value) that specifies the location of a point on a graph. For an astronomical body, its celestial coordinates are declination and right ascension. | coordinate |
| Celestial latitude. Angular distance north or south of the celestial equator measured in degrees. | declination |
| The amount of matter (mass) contained in a single volumetric unit of a substance. | density |
| Two stars revolving around each other such that they periodically pass in front of each other relative to the observer. | eclipsing binary |
| A collection of millions of stars that are arranged in a variety of patterns around a gravitational center. | galaxy |
| An upright object set in place for the purpose of casting a shadow in sunlight. By observing its shadow, early astronomers could determine the time of day, the time of year, and the position and motion of certain heavenly bodies. | gnomon |
| An astronomical reflecting telescope placed in Earth orbit by the space shuttle in 1990. The HST has provided amazing images of the universe that have changed the course of astronomy. | Hubble Space Telescope |
| The measure of the brightness of a star; a measure of the amount of energy released by an earthquake. | magnitude |
| A cloud of gas and dust in outer space; may be a bright, dark, or emission nebula. | nebula |
| A small, extremely dense, dark starlike object made of neutrons. Because of its high density, only high-energy rays can escape its gravity. | neutron star |
| A telescope in which light from an object is collected by a concave mirror mounted at the bottom of a rigid tube, reflected to a small diagonal mirror near the top of the tube, and then reflected out through the side of the tube to the eyepiece. | Newtonian reflector |
| A star that explodes and increases in brightness up to ten magnitudes but is not destroyed in the process. It may explode again later. | nova |
| The lens nearest the object in a compound optical instrument. In astronomy, the large, light-gathering lens of a refractor telescope. | objective lens |
| The eyepiece of an optical instrument such as a telescope. | ocular |
| In general, the length of time it takes a repeating event. Examples include the time required for a complete Cepheid variable cycle or for a satellite to make one complete orbit. | period |
| The reference line for celestial longitude, extending from the north to the south celestial poles through the point of the vernal equinox. Position of zero hours of right ascension. | prime hour circle |
| The portion of a star's motion that is perpendicular to an observer's line of sight. The star's apparent motion across the face of the heavens, not due to parallax. | proper motion |
| A navigational instrument used to measure a star's angular position above the horizon. A quadrant's frame, or sector, forms a 90 degree angle and contains an angular scale and a sighting mirror attached to a movable arm. | quadrant |
| An unusually bright celestial object that produces strong radio emissions. Most seem to be distant and are moving rapidly away from the earth. They have unusual properties compared to other celestial objects. | quasar |
| The portion of a star's that is either directly toward or away from the observer. | radial motion |
| A radio receiver with a large, dish shaped antenna system. It receives, focuses, amplifies, and analyzes radio waves from outer space. In some telescopes, radio signals can be transmitted as well, just as in standard radar systems. | radio telescope |
| The difference in the observed wavelengths of light from a celestial body compared to the wavelengths emitted at the source. | red shift |
| Any one of several telescope designs that uses a concave mirror as the primary light gathering optical component. | reflector telescope |
| A telescope that uses only lenses to concentrate the light from an object and focus it into an image. | refractor telescope |
| The ability of a lens or mirror to visually separate two objects that are separated by a small angle. | resolution |
| Celestial longitude; measured in hours, minutes, and seconds east of the prime hour circle. | right ascension |
| A composite telescope that uses a spherical concave main mirror and a spherical convex secondary mirror arranged according to the Cassegrainian design. | Schmidt-Cassegrainian |
| A group of stars that appear to be relatively close to each other and have the same radial and proper motions. | star cluster |
| A term used to classify the largest and most luminous stars. Typically they are fifteen to twenty times as massive as our sun, but they are several hundred times as large and are much more luminous. | supergiant |
| A star that suddenly increases its apparent brightness by about twenty magnitudes because of an explosion that essentially destroys it. | supernova |
| A measure of the average energy of motion (kinetic energy) of the atoms or molecules of a substance, stated in degrees. It is also the measure of the hotness or coldness of an object. | temperature |
| The horizontal distance from on wave crest to the next wave crest. | wavelength |
| A very dense, very bright star of about the same mass as the sun but only about a hundredth of its diameter. White dwarfs in binary systems may produce novas. Some may be remnants of supernovas. | white dwarf |
Created by:
marchscience
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