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Astronomy 1
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38
Astronomy
Undergraduate 1
02/02/2011

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Term
673,948,000 in SN
Definition
6.73948 x10^8
Term
84,261,000,000,000
Definition
8:4261 x10^13
Term
9,241,000,000
Definition
9:241 x10^9
Term
1.90 x10^27
Definition
1,900,000,000,000,000,000,000,000,000
Term
3.16 x10^7
Definition
31,600,000
Term
9.46 x10^12
Definition
9,460,000,000,000
Term
0.000001
Definition
10^-6
Term
0.00000035
Definition
3.5 x10^-7
Term
0.00000000000000000000000000167
Definition
1.67 x10^-27
Term
What do astronomers mean by a “constellation”?
Definition
Astronomers divide the sky into 88 contiguous regions called constellations
Term
Define the term Astronomical Unit (AU).
Definition
the average distance between the Earth and the Sun. It is approximately equal to 150 million km.
Term
What is the zodiac?
Definition
The zodiac is the band of sky where the Sun, Moon, and planets are found. There are
12 classical constellations that lie along the zodiac.
Term
Explain why we see different constellations at different times of the year.
Definition
We are not able to see the constellations in the region where the Sun appears. Instead, we see the
stars in the direction of the night side of the Earth
Term
Describe how the pointer stars in the Big Dipper are used to find Polaris.
Definition
The pointer stars are the two stars at the far end of the bowl from the handle. Motion
along the line defined by these stars, out of the bowl, leads to Polaris—the North Star.
Term
Explain what actually moves outward with a water wave that is generated by dropping a pebble
in a pond.
Definition
Wave crests and energy move outward with the wave.
Term
What is electromagnetic radiation? What effect does it have on electrons?
Definition
Electromagnetic radiation (light) is a means by which energy is transported through
space as a wave. This wave causes electrons to oscillate back and forth as it passes.
Term
What is the physical significance of the speed of light?
Definition
The speed of light (in a vacuum) is the absolute speed limit in the universe.
Term
define wavelength
Definition
Wavelength is the distance between successive wavecrests.
Term
define frequency
Definition
Frequency is the number of
wavecrests passing a point per time.
Term
define amplitude
Definition
Amplitude is the height of the wave above the undisturbed
level.
Term
Suppose that ocean waves travel at 2 meters per second. If the wavelength is 4 meters, what is the
frequency of the waves?
Definition
Study sheet.
Term
What is a nanometer (nm)?
Definition
A nanometer is one-billionth of a meter.
Term
What is the approximate range of wavelength for visible light?
Definition
700 nm (red) to 400 nm (violet).
Term
What is a photon? What are its properties?
Definition
A photon is the smallest unit of electromagnetic
radiation and cannot be divided. The energy of a photon is proportional to its frequency
and thus inversely proportional to its wavelength.
Term
Define transverse waves
Definition
waves perpendicular to direction, example up and down waves.
Term
define longitudinal wave
Definition
waves parallel to direction, example compression wave
Term
types of electromagnetic radiation in order of increasing wavelength.
Definition
Electromagnetic radiation from shortest to longest wavelength:
gamma-ray, X-ray, ultraviolet, visible, infrared, microwave, radio
Term
Explain how the Kelvin (absolute) temperature scale is defined.
Definition
is defined so that its zero corresponds to absolute zero and the degree
size is the same as for the Celsius scale. There are no negative temperatures on the Kelvin scale.
Term
K = C + 273, C = K - 273
Definition
K = C + 273, C = K - 273
Term
3 temps of absolute zero? CFK
Definition
F: -459
C: -273
K: 0
Term
3 temps of water freezing point
Definition
F: 32
C: 0
K: 273
Term
3 temps of water boiling point
Definition
F: 212
C: 100
K: 373
Term
Explain what black body radiation is.
Definition
Black body radiation is produced by an ideal absorber and emitter of electromagnetic
radiation. (perfect smooth spectrum)
Term
What is a spectrum?
Definition
spectrum is a separation of light (electromagnetic radiation) into its constituent
wavelengths, using a prism or grating
Term
Why are spectra useful to astronomers
Definition
allows astronomers to determine the physical nature of
the object that emits the light, e.g. a gas cloud, star, or galaxy.
Term
What is a spectral line
Definition
a sharp peak or dip in a spectrum at a particular wavelength.
Term
difference between emission and absorption lines.
Definition
peak
is called an emission line, while a dip is called an absorption line.
Term
What is the relation between the size of an electron orbit in an atom and the energy of the orbit?
Definition
The larger the orbit, the higher its energy.
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