Astronomy+Chapter+Review+Test

Marisa Miladinovic Room: 205 2/11/09 Science Page: 28-29 (1-5, 6-15, and 20)

1. An optical instrument for making distant objects appear larger and therefore nearer. One of the two principal forms (//**refracting telescope**//) consists essentially of an objective lens set into one end of a tube and an adjustable eyepiece or combination of lenses set into the other end of a tube that slides into the first and through which the enlarged object is viewed directly; the other form (//**reflecting telescope**//) has a concave mirror that gathers light from the object and focuses it into an adjustable eyepiece or combination of lenses through which the reflection of the object is enlarged and viewed.

2. The //**Celestial Equato**//r is a great circle that is a projection of the Earth's equator onto the sky. It always intercepts **//horizon//** at exact west point. Its meridian altitude, 90 degrees, is the observer's latitude. We see one-half of its circle at a time (12 hours worth).

3. //**X-rays**// have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (30 × 1015 Hz to 30 × 1018 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays. //**Microwaves**// are electromagnetic waves with wavelengths ranging from 1 mm to 1 m, or frequencies between 0.3 GHz and 300 GHz.

4. **//Right ascension//** is the astronomical term for one of the two coordinates when using the of a point on the celestial sphereequatorial coordinate system. The other coordinate is the declination. In astronomy, **//declination//** is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Dec is comparable to latitude, projected onto the celestial sphere, and is measured in degrees north and south of the celestial equator.

5. A **//leap year//** is a year containing one or more extra days (or, in the case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year. A //**light-year**// or **//light year//** is a unit of length, equal to just under ten trillion kilometers. As defined by the International Astronomical Union (which is the body which has the jurisdictional authority to promulgate the definition), a light-year is the distance that light travels in a vacuum in one Julian year.

6. A

7. B

8. C

9. B

10. A

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