147 terms

Astronomy Final


Terms in this set (...)

apparent path of the sun, the projection of Earth's orbit on the sky, and the centerline of the zodiac
did not accept a heliocentric model of the universe
is the point on the celestial sphere directly above the observer in the sky
The North Pole
where you would observe all the stars that lie north of the celestial equator to be circumpolar
Venus orbits the sun??
Galileos' observations of the gibbous phase of Venus proved it..
Northern Hemispheres winters are colder than their summers why?
the light from the sun shines more directly on the northern hemisphere during the summer ~the period of sunlight is longer during the summer than during the winter
A totally eclipsed Moon glows coppery red because..
only red light is able to pass completely through Earth's atmosphere and reach the Moon.
The visible light we see from the Moon and planets is due to..
sunlight reflected from their surfaces and/or clouds
Spring tides occur when?
at new Moon and full Moon
Kepler's first law of planetary motion implies that..
the distance between the planet and the sun changes as the planet orbits the sun
The magnitude scale
can be used to indicate the apparent intensity of a celestial object.
Tycho Brahe's greatest contribution to astronomy was..
his 20 years of careful observations of the planets.
Intensity is..
is the measure of the star's apparent visual magnitude
What do astronomers mean by light pollution?
lights from human sources that make it difficult to see the stars at night
Galileo's telescopic discoveries of mountains and spots on the moon and sun were controversial why?
it suggested that the Moon and Sun were not perfect spheres
From Kepler's Third Law..
an asteroid with an orbital period of 8 years lies at an average distance from the sun equal to 4 AU
Polaris, seen from the northern latitudes..
is always above the northern horizon
Ptolemy's model of the universe..
contained epicycles
Celestial equator is..
a line around the sky directly above Earth's equator, the dividing line between the north and south celestial hemispheres.
Precession of the rotation axis of Earth is caused by..
the force of gravity from the sun and moon on Earth's equatorial bulge.
An annular solar eclipse is..
a solar eclipse that occurs when the Moon's umbra does not reach Earth's surface
Astronomers build telescopes on tops of mountains because..
there is less air to dim the light and the seeing is better
Total lunar eclipses always occur..
at the time of a Full Moon
Kepler's Second Law implies that..
a planet should move at its greatest speed when it is closest to the sun
The language that most star names are in, such as Deneb and Betelgeuse
New generation telescopes use..
active optics to control the shape of the mirror, use segmented mirrors, and use mirrors that are very thin.
Rays that have wavelengths that are longer than visible light..
Gamma-Rays, Ultraviolet Light, and X-Rays
A Solar and Lunar Eclipse will occur when..
the Moon is full or new
1 AU =
the average distance from Earth to the Sun
The Copernican system was no more accurate than the Ptolemaic system in predicting the positions of the planets because..
the Copernican system included uniform circular motion
Increasing the diameter of a telescope..
increases its light gathering power and increases its resolving power
Neap Tides
occur when the Moon is First or Last (Third) Quarter
During a total lunar eclipse..
The moon is in Earth's umbra and the Moon is full
Interstellar clouds may collapse to form stars if they..
encounter a shock wave
Stars in a star cluster..
all have the same age and have the same chemical composition
Our sun is a star of spectral type..
Absolute Visual Magnitude is
the apparent magnitude of a star observed from a distance of 10 pc
Super Giant star..
is the most dense
The theory that the collapse of a massive star's iron core produces neutrinos was supported by..
the detection of neutrinos from the supernova of 1987
The sun's magnetic field is evident in the looped shapes of..
Stars with masses between 0.4 M and 4 M..
undergo thermonuclear fusion of hydrogen and helium, but never get hot enough to ignite carbon
The most common stars are..
lower main sequence stars
The Zeeman Effect
is produced by atomic transitions in the presence of a strong magnetic field.
The Great Nebula in Orion
is an emission nebula
In the H-R diagram, 90% of all stars are
on the main sequence
The maximum mass of a white dwarf is..
about 1.4 times the mass of our Sun
Planetary Nebula is..
Gas ejected from a low-mass star in the final stage of its life.
Sunspots are
cooler than their surroundings
Which of the following can be determined by using the Doppler effect?
The speed at which a star is moving away from an observer, the radial velocity of a star, and the speed at which a car is traveling toward an observer.
The CNO cycle..
is the thermonuclear fusion of hydrogen to form helium operating in the cores of massive stars on the main sequence.
Granulation is caused by..
rising gas below the photosphere.
What causes hydrostatic equilibrium? (the outward pressure that balances the inward pull of gravity in a star)
the outward flow of energy
The spectral sequence in order of decreasing temperature is..
OBAFGKM (Oh Be A Fine Guy Kiss Me)
The event horizon
has a radius equal to the Schwarzschild radius.
When does a star become a main sequence star?
When the rate of hydrogen fusion within the star's core is high enough to sustain gravitational equilibrium.
The lowest mass object that can intricate thermonuclear fusion of hydrogen has a mass of about..
0.08 M
The corona and chromosphere of the Sun are believed to be heated by..
high energy particles accelerated by the Sun's magnetic field.
Giant and supergiant stars are rare because..
the giant and supergiant stage is very short.
After a supernova event, what is left behind?
either a neutron star or a black hole
A recent sunspot maximum occurred in 2001, what is the year of the sunspot maximum that immediately follows the 2001 maximum if the solar cycle continues?
In the proton-proton chain..
energy is produced in the form of gamma rays and the velocity of the created nuclei.
A type II supernova
occurs when the iron core of a massive star collapses.
In A.D. 1054, Chinese astronomers observed the appearance of a new star, whose location is now occupied by..
a pulsar, a neutron star, and a supernova remnant
As material flows into a black hole..
the material will experience time dilation and will become hotter.
A white dwarf is composed of
carbon and oxygen nuclei and degenerate electrons
2 most abundant elements in the Sun are..
hydrogen and helium
Most of the light we see coming from the Sun originates in the
How does the Sun generate energy today?
nuclear fusion
Measured ages of globular clusters and a study of the time required for massive stars to build up the present abundance of heavy elements suggests that the universe is..
at least 14 billion years old.
Whether the universe is open, closed, or flat depends on the..
density of the universe
The disk of the Milky Way is approximately..
80,000 light-years in diameter.
The resolution of Olbers' paradox suggests that the night sky is dark because
the universe is not infinite in age.
A group of 10 to 100 stars that formed at the same time but are so widely scattered in space their mutual gravity cannot hold them together is called..
an association
Which of the following is not a characteristic of the stars of the disk component of our galaxy?
randomly inclined orbits
The nuclear bulge of our Galaxy
contains stars primarily associated with the spherical component of our Galaxy
Harlow Shapley
first calibrated the Cepheid variable stars for use in determining distance
Younger stars have more heavy elements because..
the heavy elements were made in previous generations of stars
The cosmic background radiation comes from a time in the evolution of the universe
when electrons began to recombine with nuclei to form atoms
Why do we call dark matter "dark"?
it emits no radiation that we have been able to detect
The orbits of population I stars..
are confined to the disk of the galaxy and are nearly circular
The most common type of galaxy in the universe is expected to be
the elliptical galaxies
Sgr A* is believed to be the center of the Milky Way Galaxy because..
It lies in the general direction of the center of the galaxy based on observations of globular clusters ~It does not move with respect to the rest of the galaxy
Galactic cannibalism refers to..
the merging of galaxies
Current evidence suggests that the universe is..
flat, infinite, and accelerating in its expansion
Why do we think that most of the mass of the Milky Way is in the form of dark matter?
The orbital speeds of stars far from the galactic center are surprisingly high, suggesting that these stars are feeling gravitational effects from unseen matter in the halo.
Population II stars
are primarily old low mass stars and are located in globular clusters
In 1998 it was announced that the expansion of the universe is accelerating. What does this imply from the perspective of the Big Bang?
A force exists that we knew nothing about that causes the expansion.
Supermassive black holes are believed to be located at the center of many galaxies because..
the orbital motion of material near the center is very fast and indicates a very massive core.
What are Magellanic Clouds?
Two small galaxies that probably orbit the Milky Way Galaxy
Quintessence is the name of the..
force suspected to cause the current acceleration in the rate of expansion of the universe.
The center of our galaxy lies in the direction of the constellation of..
We should expect galaxies to collide fairly often because..
they are large with respect to their separation distances and galaxies occur in clusters
Starburst galaxies..
are often associated with a galaxy that is colliding with another galaxy
The look-back time is
the time it takes for the light from an object to reach Earth, and numerically equal to the distance in light-years.
Henrietta Leavitt
first noticed that for Cepheid variable stars, there was a direct relation between the luminosity and the period of the variation in their brightness.
The chemical abundance of population I stars..
indicates that the material they formed from had been enriched with material from supernovae.
Seyfert galaxies..
are more common in close pairs of galaxies than in isolated systems and emit more energy at x-ray, ultraviolet, infrared, or radio wavelengths that normal spiral galaxies.
According to the analysis of the WMAP spacecraft the universe contains 73%..
dark energy
Which of the following is NOT used as a distance indicator?
Herbig-Haro objects
The Milky Way Galaxy is part of..
the Local Group
The central galaxy in a double-lobed radio source is usually..
a giant elliptical galaxy
The age of the Milky Way Galaxy has been estimated to be at least 13 billion years based on..
observations of globular clusters
Astronomers calibrated (BLANK) to find the distances to the farthest visible galaxies and measure the expansion rate of the universe.
type Ia supernovae
William Herschel
attempted to gauge the true shape of the Milky Way star system by counting stars in 683 different directions in the sky.
The Sun is located about (BLANK) from the center of the Milky Way Galaxy to the edge.
The largest member of the Local Group is..
Andromeda Galaxy (M31)
Globular Clusters
are spherical groups of 100,000 to 1,000,000 population II stars firmly bound by gravity.
Kung Bushmen
called the Milky Way "the backbone of night"
The rotation of Uranus is peculiar in that
the axis is nearly parallel to the plane of its orbit
The lunar maria are
the lava plains of the lunar lowlands
The moons of Mars are believed to be
captured by asteroids
The Cassini spacecraft is currently in orbit around the planet..
Valles Marineris
is a very long and deep canyon on Mars
Belt and zone circulation
is caused by rising and sinking gases.
Lobate scarps
are believed to have formed on Mercury when the planet's interior cooled and shrank.
The geology of Venus appears to be dominated by
The Kuiper Belt
is a disk-shaped cloud of icy bodies believe to extend from about 30 AU out to 100 AU. It is believed that short period comets originate from this region.
The large planetesimals would have grown faster than the smaller planetesimals because...
their stronger gravity would pull in more material.
Which of Jupiter's satellites are geologically active ?
Io and Europa
Which of the following objects may have organic particles on its surface as a result of the interaction of sunlight with methane in its upper atmosphere?
The first planets around other Sun-like stars were discovered?
almost 2 decades ago
The surface of Venus has been studied..
using radar maps made from Earth, using radar maps made from satellites orbiting Venus, and using spacecraft spacecraft that have landed on the surface of Venus.
Saturn's atmosphere is
hazy above the clouds.
The impact of a large comet with Earth has been suggested to have caused the extinction of the dinosaurs. The impact site of this comet is in or near
Chicxulub, Mexico
Although officially classified as a dwarf planet, Pluto is best explained as
one of the larger Kuiper belt objects.
Percival Lowell
In the late 19th century he postulated that the supposed inhabitants of Mars built a vast system of irrigation canals to transport water from the polar caps.
Which of the following is NOT a characteristic of the terrestrial planets?
low average density
The Moon is no longer geologically active because..
it is too small.
Earth's atmosphere contains only small amounts of carbon dioxide because..
carbon dioxide dissolves in water and most of it is now contained in the oceans and carbonate rocks.
is the largest satellite (moon) of Pluto.
Which hypothesis concerning the formation of the Moon makes predictions that best fit the observed lunar data?
The Large Impact hypothesis
51 Pegasi is an important object because..
it is the first star like our sun that was found to have a planet orbiting it
The flow patterns found on the surface of Mars suggest
that the climate on Mars was different in the past.
Saturn's rings are
composed of ice particles, within the planet's Roche limit, and are in the plane of the planet's equator.
Most of the asteroids orbit the Sun in a belt between the orbits of which planets?
Mars and Jupiter
The gas tail of a comet always..
points away from the Sun.
The most successful method thus far for detecting planets around other stars is..
the radial velocity method.
Though Titan is small, it is able to retain an atmosphere because..
it is very cold.
The short-period comets do not have randomly oriented orbits because..
they formed in the Kuiper Belt, a belt shaped region in the plane of the solar system.
A meteor shower is produced when..
Earth passes through the orbital path of a comet.
The excess heat produced by Jupiter and Saturn is the result of..
the continual slow contraction of each planet.
According to current science, why is Mars red?
chemical reactions between surface rock and atmospheric oxygen literally rusted the surface.
Which planet has the highest average surface temperature and why?
Venus, because of its dense carbon dioxide atmosphere.
Which one of the following objects is most like the planetesimals that formed in the solar nebula?
That Mercury has a large iron core is evidenced by..
the large mean density of Mercury.
A bit of matter that enters Earth's atmosphere and survives to reach the ground is called..
a meteorite
The condensation sequence suggests that (BLANK) should condense closest to the Sun.
metals and metal oxides