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30 terms

Exam #1 corrected answers

York College@ CUNY ASTR 101 Y Dr.I.E.Ekejiuba Fall2011
STUDY
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About how many stars are visible on a clear, dark night with the naked eye alone?
a few thousand
Into how many constellations is the celestial sphere divided?
88
What is the range of values for declination?
+90 to -90 degrees
How long is the precession cycle?
26,000 years
The places where the sun crosses the equator are called the?
equinoxes
What celestial line is a product of the earths orbit around the sun
ecliptic
A solar eclipse can only happen during a
perihelion passage of the sun
A lunar eclipse can only happen during a
new moon
Which of the following describes parallax?
It is inversely proportional to the distance to the star
A star with a large parallax
is a short distant from Earth
The Ptolemaic model probably persisted for all these reasons EXCEPT:
it was consistent with the doctrines of the Catholic Church
The Ptolemaic model of the universe:
explained and predicted the motions of the planets with deferents and epicycles
Scientists today do not accept the Ptolemaic model because:
the work of Tycho and Kepler showed the heliocentric model was more accurate
On which of these assumptions do Ptolemy and Copernicus agree?
all orbits must be perfect circles
A planet whose distance from the sun is 3 A.U. would have an orbital period of how many Earth-years?
5.2
Which was a contribution to astronomy made by Copernicus?
The planets move around the Sun in elliptical orbits
A fatal flaw with Ptolemy's model is its inability to predict the observed phases of
Mercury and Venus
Upon which point do Copernicus and Kepler disagree?
The orbit of the planets are ellipses, with one focus at the Sun
What does Kepler's third law imply about planetary motion?
Planets further from the Sun orbit at a slower speed than planets closer to the Sun
The place in a planet's orbit is closet to the Sun is called
perihelion
The force of gravity varies with
both product of the two masses and inverse square of the distance separating the two bodies
How much stronger is the gravitational pull of the sun on Earth, at 1AU, than it is on Saturn at 10 AU
100
If a wave's frequency doubles, its wavelength
is halved
Which of these is constant for ALL types of electromagnetic radiation in a vacuum?
velocity
The two forms of electromagnetic radiation that penetrate the atmosphere best are:
visible and radio waves
According to Wien's Law, if the surface temperature is increased by a factor of 2, its peak wavelength will
decrease by a factor of 2
Stefan's Law says:
that if the Suns temperature were doubled, it would give off 16 times more energy
The three laws dealing with the creation of various spectra are due to:
Kirchhoff
The particle which adds mass but no charge to the atomic nucleus is the
neutron
Which of these is the classic continuous spectrum?
a rainbow