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Astron quiz 1
astron
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Astronomy
Undergraduate 1
02/16/2012

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Term
Who developed the first reflecting astronomical telescope
Definition
Isaac Newton
Term
What causes chromatic aberration in the objective lens of a telescope?
Definition
Different colors are refracted through different angles at each surface of the lens.
Term
The light-gathering power of a telescope is related directly to
Definition
the area of the primary mirror or len
Term
At what distance from the objective lens in a refracting telescope is the image formed
Definition
Its focal length
Term
Who first discovered that radio radiation can be received from astronomical objects?
Definition
Karl Jansky
Term
In telescopes, the diffraction limit is worse (i.e., largest) fo
Definition
smaller diameter lenses or mirrors and longer wavelength light (or other electromagnetic radiation)
Term
The PRIMARY reason for spreading many radio telescopes across a large area and combining the signals at a central station is
Definition
to produce much sharper images of radio sources.
Term
What is the MAIN reason for placing astronomical telescopes and detectors on satellites?
Definition
To get above the absorption in the Earth's atmosphere.
Term
Who was the first person to suggest that light is an electromagnetic wave?
Definition
James Clerk Maxwell
Term
In what way does a photon of blue light NOT differ from a photon of yellow light, in a vacuum
Definition
Speed
Term
the correct sequence of electromagnetic radiation, in order of increasing energy of the photons
Definition
Visible light, UV radiation, X-rays, gamma rays
Term
wave NOT electromagnetic in nature?
Definition
Seismic waves
Term
The word "planet" is derived from a Greek term meaning
Definition
wanderer
Term
Retrograde motion of a planet i
Definition
westward motion against the star background
Term
In Ptolemy's geocentric theory of the solar system, what name is given to the small circle around which the planet moves while the center of this circle orbits the Earth
Definition
Epicycle
Term
The major contribution of Tycho Brahe to the development of modern astronomy was to
Definition
measure planetary positions very accurately.
Term
The major contribution of Johannes Kepler to the development of modern astronomy was to
Definition
prove that planetary orbits are ellipses.
Term
The semi-major axis of an ellipse is
Definition
the distance from the center of the ellipse to one end, along the largest diameter of the ellipse
Term
The major contribution of Galileo to the development of modern astronomy was to
Definition
discover the satellites (moons) of Jupiter.
Term
Kepler's third law
Definition
The larger the orbit, the longer it takes for the planet to complete one orbit.
Term
One light-year is a distance of approximately
Definition
6.3 x 104 km
Term
How much of the overall sky is above the celestial equator, that is, in the northern hemisphere?
Definition
More than one half, because of the location of the poles.
Term
The difference in declination angles between the North and South celestial poles is
Definition
180 degrees
Term
Speed of light
Definition
300,000 Km/s
Term
Light waves are
Definition
electromagnetic radiation
Term
All matter is made up of
Definition
protons, electrons, and neutrons
Term
moving pattern of electric magnetic forces
Definition
electromagnetic radiation
Term
Defining property of a light wave
Definition
wavelength
Term
energy in a wave is proportional to
Definition
Frequency
Term
units to measure wavelengths
Definition
nanometers
Term
opacity
Definition
the extent to which radiation is blocked
by the material it is travelling through
Term
clouds absorb
Definition
visible light
Term
ozone layer absorbs
Definition
ultraviolet, x-ray, and gamma-ray radiation
Term
water vapor and carbon dioxide absorb
Definition
infrared light
Term
First telescope
Definition
optical telescope
Term
refractors
Definition
use lenses
Term
reflectors
Definition
use mirrors
Term
focal point
Definition
glass is suitably curved, it can be used to bring all
of the light to the same location
Term
mirrors focal plane
Definition
curved mirror so that all of the light from a distant source is reflected to the same place
Term
Prime Focus
Definition
light comes to a focus in the focal plane
Term
newtonian Focus
Definition
light is reflected from a secondary
mirror to the side of the telescope
Term
Cassegrain focus
Definition
light is reflected from a secondary
mirror down through a hole in the primary mirror
Term
Coude Focus
Definition
light is reflected from a secondary
mirror and brought to a focus in an adjacent room
Term
chromatic aberration
Definition
The amount of refraction that light undergoes depends
on its color
Term
amount of light that is gathered
Definition
depends on the
area of the primary mirror or lens
Term
Diffraction Limit
Definition
Every telescope has a fundamental minimum resolution
Term
Small diffraction limit
Definition
makes it possible to see very
fine details
Term
large diffraction limit
Definition
can make some things look blurry
Term
Telescopes diffration limit
Definition
inversely proportional
to its diameter
Term
Active optics
Definition
make rapid changes to the tilt of the mirror
to compensate for degraded image quality
Term
Adaptive optics
Definition
actually deforming
the mirror to correct for the effects of seeing
Term
Speckle interfermetry
Definition
involves the adding up of a
sequence of very short exposures, each too brief for the
Earth’s atmosphere to change significantly
Term
interferometry
Definition
the simultaneous observation of
an object using two or more telescopes
Term
AU
Definition
1 AU equals the average distance between the Earth and Sun
1 AU = 149,000,000 km
Term
Nearest star to the sun
Definition
Proxima Centauri
270,000 AU away
4.2 LY
Term
Speed light travels at
Definition
300,000 KM/s
Term
Age of the universe
Definition
13.7 Billion years old
Term
Zenith
Definition
Place directly above you
Term
Earths rotation
Definition
sidereal day
Term
celestial sphere
Definition
This imaginary sphere can be thought of as a giant empty
ball which surrounds the Earth, and has the stars
attached to its inside
Term
celestial north and south poles
Definition
outward
extensions of the Earth’s poles
Term
right
ascension and declination
Definition
describe the location of an
object on the sky
Term
ecliptic plane
Definition
The circular path of the Sun on the sky is referred to as
the
Term
Keplers 1st law
Definition
Planets have elliptical orbits, with the Sun at one focus.
Term
Keplers
Definition
An imaginary line between the Sun and a planet sweeps
out equal areas of the ellipse in equal time intervals
Term
Keplers 3rd law
Definition
The square of a planet’s orbital period (T) is
proportional to the cube of its semi-major axis (a).
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