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Astronomy Final
AST1002 FSU collage of previous Qs.
82
Astronomy
12/03/2008

Additional Astronomy Flashcards

 


 

Cards

Term
How much stronger is the gravitational pull of the Sun on Earth, at 1 AU, than it is
on Saturn at 10 AU? (gravitational pull refers to the acceleration due to gravity on the planet)
Definition
100 times
Term
A star with a declination of +40.0 degrees will be
Definition
north of the celestial equator.
Term
If a wave’s frequency doubles, its wavelength
Definition
is halved.
Term
What problem do refractor telescopes have that reflectors don’t?
Definition
Chromatic aberration
Term
Planetary orbits (in our solar system)
Definition
are almost circular, with low eccentrities.
Term
At what phase(s) would you expect to find extremely high and low tides?
Definition
both new and full Moons
Term
If the Earth were in an orbit farther from the Sun than it is now,
Definition
the year would be longer.
Term
Which answer has these colors in order from the longest wavelength to the shortest?
Definition
Red, green, blue
Term
What is the resolution of a telescope?
Definition
Its ability to distinguish two adjacent objects close together in the sky
Term
A blackbody has a temperature of 1,000 K and emits mostly
Definition
infrared light.
Term
If an electric field wave oscillates north and south (horizontally), and the electro-
magnetic wave is traveling vertically straight up, then what direction does the magnetic field wave
oscillate?
Definition
East and west (horizontally)
Term
When a thin crescent of the Moon is visible just before sunrise, the Moon is in its
Definition
Waning Phase
Term
Which of the following stellar properties can you estimate simply by looking at a
star on a clear night?
Definition
Both brightness and surface temperature
Term
Green light has a shorter wavelength than orange light. In a 5-inch telescope, green
light will
Definition
provide better angular resolution than orange light.
Term
Kepler’s first law worked, where Copernicus’ original heliocentric model failed,
because Kepler described the orbits as
Definition
elliptical, not circular.
Term
A meteor is
Definition
a streak of light in the atmosphere.
Term
Atoms have particular associated spectral lines because
Definition
electrons have only certain allowed orbits.
Term
The best test of a scientific hypothesis is how
Definition
well it predicts new observations.
Term
The temperature scale that places zero at the point where all atomic and molecular
motion ceases is
Definition
Kelvin.
Term
The average rate of erosion on the Moon is far less than here because
Definition
the Moon lacks wind, water, and an atmosphere.
Term
The tail of a comet always points
Definition
away from the Sun and becomes longest and brightest at perihelion.
Term
Compared to optical photons
Definition
1. radio photons have a longer wavelength.
2. X-ray photons have a larger frequency.
3. infrared photons have a smaller energy.
Term
As a rotating gas cloud contracts, it spins
Definition
faster due to conservation of angular momentum.
Term
The Kuiper Belt is found where in the solar system?
Definition
Beyond the orbit of Neptune
Term
In noting that the Earth is “differentiated”, we mean that
Definition
the density increases as you descend downward toward the core.
Term
Relative to the comet, the direction of the ion tail tells us
Definition
the direction of the Sun.
Term
What will occur when the full Moon is on the ecliptic?
Definition
A total lunar eclipse
Term
Why do Mercury and the Moon have almost no atmosphere?
Definition
The gravity at their surfaces is low, so most gas molecules travel fast enough to escape the
planet.
Term
The observed spectral lines of a star are all shifted towards the red end of the
spectrum. Which statement is true?
Definition
This is an example of the Doppler effect.
Term
What would the days and seasons be like if the Earth still rotated at the same
speed, but the Earth’s axis were tilted nearly 80 degrees on its side instead of 23 degrees?
Definition
The days and seasons would be the same lengths as ours, but the seasons would have more
extreme temperature changes.
Term
If a wave’s frequency is halved, its wavelength
Definition
is doubled.
Term
A blackbody has a temperature of 6,000 K and emits mostly
Definition
visible light.
Term
Blue light has a shorter wavelength than orange light. In a 5-inch telescope, blue
light will
Definition
provide better angular resolution than orange light.
Term
The Sun is a stable star because
Definition
gravity balances forces from pressure.
Term
What is thought to cause Io’s volcanism?
Definition
Tidal stresses from both Jupiter and Europa
Term
The magnetic fields of which two planets are most unusual?
Definition
Uranus and Neptune
Term
Rigel has an apparent magnitude of +0.18 and Betelgeuse an apparent magnitude of
+0.45. What can you conclude from this?
Definition
Rigel is brighter than Betelgeuse.
Term
Some regions along the plane of the Milky Way appear dark because
Definition
stars in that region are hidden by dark dust particles.
Term
The critical temperature the core must reach for a star to shine by fusion is
Definition
10 million K.
Term
Interstellar dust clouds are best observed at what wavelength?
Definition
Radio and infrared
Term
Which are the four Galilean moons of Jupiter?
Definition
Io, Europa, Ganymede, and Callisto
Term
Inside the Roche Limit
Definition
large moons are torn apart.
Term
A cloud fragment too small to collapse into a main sequence star becomes a
Definition
brown dwarf.
Term
A moon with a smooth, uncratered surface would imply
Definition
the surface is very young.
Term
How do the atmospheres of Earth’s Moon and Mercury compare?
Definition
Neither body has a permanent atmosphere.
Term
On the H-R diagram, red supergiants like Betelgeuse lie
Definition
at the top right.
Term
The reason the Jovian planets lost very little of their original atmosphere is due to
their
Definition
large mass.
Term
A solar-mass star will evolve off the main sequence when
Definition
it builds up a core of inert helium.
Term
Today, the primary source of the Sun’s energy is
Definition
the strong force fusing hydrogen into helium.
Term
Of the elements in your body, the only one not formed in stars is
Definition
Hydrogen
Term
A star will spend most of its life
Definition
on the main sequence.
Term
Emission nebulae like M-42 occur only near stars that emit large amounts of
Definition
ultraviolet radiation.
Term
Stellar parallax is used to measure the
Definition
distances of stars.
Term
The speed of light is 3 · 108 m/s. If 2.00 kg of mass is converted to energy, how
much energy will be produced?
Definition
1.8 · 1017 J
Term
A star’s apparent magnitude is a number used to describe how our eyes measure its
Definition
brightness.
Term
What would Jupiter have needed to be a star?
Definition
More mass to make the planet hotter
Term
The parallax of a certain star was found to be 0.01 arc-seconds. Find the distance
to this star in pc.
Definition
100 parsecs
Term
The temperature of the Sun’s photosphere is about
Definition
5,800 K
Term
A star’s color index directly tells us its
Definition
temperature.
Term
Many astronomers believe Pluto is perhaps best classified as
Definition
a large Kuiper Belt object.
Term
The number of sunspots and solar activity in general peaks
1. every 27 days, the apparent rotation period of the Sun’s surface.
Definition
every 11 years.
Term
Which moon in the solar system shows a dense atmosphere?
Definition
Titan
Term
Interstellar gas is composed primarily of
Definition
90% hydrogen, 9% helium, and 1% heavier elements.
Term
Stars are often born within groups known as
Definition
clusters.
Term
What can be said with certainty about a red star and a blue star?
Definition
The blue star is hotter than the red star.
Term
A star near the lower right of the H-R diagram is likely to be
Definition
red, with low luminosity.
Term
Why is the sky blue?
Definition
Tiny particles in the air are more efficient at scattering short-wavelength light than they are
at scattering long-wavelength light.
Term
Type II supernovae occur when their cores start making
Definition
Iron
Term
Homogeneity and isotropy, taken as assumptions regarding the structure and evolution of the universe, are known as
Definition
the cosmological principle.
Term
The concept that the direction of observation does not matter overall is
Definition
isotropy.
Term
The concept that on the grandest of scales, the universe is similar in appearance everywhere is
Definition
homogeneity.
Term
Because almost all galaxies show redshifted spectra, we know that
Definition
the universe is expanding.
Term
The darkness of the night sky in an infinite universe is addressed in
Definition
Olbers' Paradox.
Term
Interstellar gas is composed mainly of
Definition
90% hydrogen, 9% helium by weight.
Term
Definition
Term
What effect does even thin clouds of dust have on light passing through them?
Definition
It dims and reddens the light of all more distant stars.
Term
Which statement about the dark nebulae is true?
Definition
They can be penetrated only with shorter waves, such as UV and x-ray.
Term
Some regions along the plane of the Milky Way appear dark because
Definition
stars in that region are hidden by interstellar gas
Term
Due to absorption of shorter wavelengths by interstellar dust clouds, distant stars appear
Definition
redder
Term
Which statement is true about the interstellar medium?
Definition
Dust blocks the longest electromagnetic wavelengths.
Term
Spectra of interstellar gas show it has the same basic composition as
Definition
stars.
Term
What is the primary visible color of an emission nebula?
Definition
red due to ionized hydrogen atoms