Space & Earth Science - Chp. 3
Terms
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- A named area of the sky
- constellation
- Early device that indicated time and season by casting a shadow.
- gnomon
- Early device that used a scale & a sight on a movable arm to measure a star's position. Also measured latitude.
- quadrant
- Uses only lenses to magnify an image. Refract means to bend light.
- refractor telescope
- the larger light-gathering lens
- objective lens
- the magnifying lens by the eye
- ocular
- The ability of a telescope to bring out details in an image.
- resolution
- The horizontal distance from one wave crest ot the next. In light each color has a different wavelength.
- wavelength
- Two or more lenses made of different kinds of glass mounted together to correct for chromatic aberration. It focuses all of the colors at the same point.
- compound lens
- Uses a mirror to gather light.
- reflector telescope
- Telescope with eyepiece on the side.
- Newtonian reflector
- Telescope with eyepiece on the bottom. It is more compact and easier to use. Problem with diffraction spikes (dark lines) caused by spider.
- Cassegrainian reflector
- Uses a combination of a lenses and mirrors.
- composite telescope
- A composite telescope with a "transparent spider". Popular with amateurs.
- Schmidt-Cassegrainian
- Only radio waves can pass through the atmosphere. Looks like a giant satellite dish.
- radio telescope
- In space above the earth's atmosphere. Primarily a reflector.
- Hubble Space Telescope (HST)
- The astronomical equivalent of latitude and longitude.
- coordinate
- Divides north from south in the sky. It is the plane of the earth's equator projected into the sky.
- celestial equator
-
Like latitude in the sky.
Measured in degrees.
North = '+'
South = '-' - declination (DEC)
-
Like longitude in the sky.
Measured in hours and minutes.
One hour = 15 degrees - right ascension (RA)
- A line passing through the celestial poles and a point called the vernal equinox. Above the prime meridian.
- prime hour circle
- A measure of a star's RELATIVE brightness. The smaller the #, the brighter the star.
- magnitude
- A method of measuring the distance to a star. The wavelengths of the light stretch with increasing distance.
- red shift
- movement across the sky
- proper motion
- movement directly toward or away from us
- radial motion
- The color of a star is the result of its surface temperature. The hottest stars are bluish. The cooler stars are more reddish.
- temperature
- A term used to classify the largest and most luminous stars.
- supergiant
- A very dense, bright star with about the same mass as the sun, but 100 times smaller.
- white dwarf
- The amount of matter contained in a unit.
- density
- Two stars in orbit around each other. Light greatest when side by side. (Variable stars)
- eclipsing binary
- A star that varies in brightness due to regular changes in size. Ex: Delta Cephei with a 4.5 day period.
- Cepheid variable
- Time between the shrinking and growing of a star. How long they go from one bright spurt to the next.
- period
- A white dwarf star that explodes periodically and gets brighter before returning to normal.
- nova
- A destructive explosion of a star.
- supernova
- The small, dense, dark star left over from a supernova.
- neutron star
- A group of related stars that have the same motion.
- star cluster
- Millions of stars that orbit the galaxy's center.
- galaxy
- Visible clouds of dust and gas in space.
- nebula
- QSOs or quasi-stellar objects. Extremely unusual objects that have astronomers puzzled.
- quasar
- An extremely dense object that can trap even light.
- black hole
- "to bend light"
- refract
- What telescope mount is the most common? The altitude is determined by the azimuth. Problem is the it doesn't work for heavy telescopes.
- Altazimuth Mount
- What telescope mount works like a cannon's mount? It can support a heavy telescope. It can lower the telescope to bring ocular closer to viewer. It is a variation of the Altazimuth Mount.
- Dobsonian Mount
- What telescope mount rotates parallel to the earth's equator?
- Equatorial or German Mount
- 2 things magnitude depends on
- A star's absolute brightness & the distance of the star from the earth.
- The actual amount of light a star emits.
- absolute brightness
- Star with the larger mass.
- Main Star in an Eclipsing Binary.
- Star with the smaller mass. Usually the brighter star.
- Companion Star in an Eclipsing Binary.