Astronomy Test II

Originally, the signals that were found to be pulsars were thought to be
little green men

If you replaced our sun with a one-solar mass black hole, Earth would
maintain its orbit

The Schwarzchild radius of our sun is
3 km

The maximum mas limit for a ___________ is 1.4 solar masses.
white dward

If a stellar remnant is greater than 1.4 solar masses but less than about 3 solar masses, the resulting object will be a
neutron star

If a stellar remnant is greater than 3 solar masses, the resulting object will be a
black hole

At the event horizon, the escape velocity is equal to
the speed of light

Who discovered the peculiar pattern of radio signals that were eventually found to be from a pulsar?
Jocelyn Bell

Black hole candidates are detectable by their accretion disks producing mainly what type of light?
X rays

The first X-ray binary suspected of harboring a black hole is
Cygnus X-1

Objects in binary system consist of neutron star accumulating material from another star on its surface, where it ignites and produces periodic _____.
X-ray bursters

When were neutron stars first predicted?

Of the following stars, the one that has the longest period of variability is
the most luminous Cepheid

Compared to open star clusters, globular clusters tend to be
poorer in metals and older

The 21-centimeter line of hydrogen is in the
radio part of the spectrum

The galactic center of the Milky Way lies in the constellation of

The approximate diameter of the disk of the Milky Way Galaxy is
75,000 light-years

In a typical spiral galaxy, stars in the
halo have elliptical orbits

The supermassive black hole at the center of the galaxy is estimated to be
2.6 million solar masses

What spectral classes of stars work best as spiral tracers?
O and B

The youngest stars are
Extreme Population I

Astronomers use the term “metals” to describe any element heavier than

A rotation curve measures
orbital velocity vs. orbital radii

The 21-centimeter radiation is used to map the galaxy to detecting
neutral (un-ionized) hydrogen

Which galactic region has the greatest metal content of stars
spiral arms

The very center of the Milky Way Galaxy is invisible at what wavelengths?

Of the following objects, the one that must be a spiral galaxy is a

The speed of a very highly redshifted quasar as determined by the relativistic Doppler formula is
less than that determined by the classical formula

Of the following objects, the one that produces the least energy is a

A BL Lac object is the same as a

Because of the large look-back times of quasars, they appear as they were when the universe was only _____ percent of its present age.

Most of the lines in the spectrum of the quasar 3C 273 are caused by

Quasar distances are estimated by
their redshifts

Eruptions of supermassive black holes in quasars may have been caused by
collisions or mergers with other galaxies

The objects that are detected at the points where the gas of a radio jet hits the extragalactic medium are called
hot spots

The evidence leads modern astronomers to conclude that at the cores of active galaxies are supermassive black holes with masses as high as
a billion solar masses

The universe has
no edge and no center

The main reason the night sky is dark is that the universe is
finite in age

Isotropy is the assumption that
the universe looks the same in every direction

According to Hubble law, if Galaxy A is 10 times more distant than Galaxy B, then Galaxy A is
receding 10 times faster than Galaxy B

The primordial background radiation is observable primarily at
radio wavelengths

Of the following groupings of galaxies, the one that is the largest in size is the
filaments and voids

The force that is NOT unified with the others in a Grand Unified Theory is the
gravitational force

The type of universe in which the average density is predicted to be greatest is the
closed universe

What did Arno Penzias and Robert Wilson initially think caused the background radiation in their microwave antenna
pigeon droppings

The type of universe that will keep expanding forever is
an open universe

A nuclear particle theory predicts the existence of massive particles that interact weakly with normal matter. These are all classified as

The orbits of planets
All lie in approximately the same plane

Each of the planets in our solar system orbits the sun
in the same direction, counterclockwise as seen from the north (above)

The orbits of the planets lie mainly in the same plane because the planets
formed from a large thin disk of material surrounding the new sun

The solar system has relatively little gas and dust between the planets. The lack of this material is probably the result of
radiation pressure from the sun

The solar nebula theory describes how the planets formed from
a disk-shaped cloud of gas and dust around the newly forming sun

The terrestrial planets near the sun are
small, solid, and rocky.

The atmosphere of the Jovian planets are made primarily of
Hydrogen and helium

Most asteroids revolve around the sun between the orbits of
Mars and Jupiter

Objects made mostly of ice that form a large gaseous “tail” that is directed away from the sun at all times are called

Formation of planetesimals by condensation refers to the process of
matter building one atom at a time

Solid particles sticking together to form larger particles describes the process of

The separation of low-density and high density materials in a planet during the early stages of its formation is referred to as

The interiors of Jupiter and Saturn consist mostly of
liquid hydrogen

Low-density and cold dust disks have been found around many stars. These disks are believed to be regions where planets have formed or are in the process of forming. The disks are most readily detected by
infrared telescopes

A planet that has formed around the star 51 Pegasi has been detected by
Doppler shifts in the star’s spectrum as the planet orbits, causing the star to wobble back and forth

The source of comets is
The Kuiper Belt and Oort Cloud

Our solar system may have a cold dusk disk similar to that found around the star Beta Pictoris. Astronomers believe that this disk is located in the ______ of objects.
Kuiper Belt.

Iron and nickel drained to the center of Earth, while at the same time, the lighter silicates rose to the surface, and formed a thin crust. This process is known as

Which of the following sequences best describes the four-stage history of Earth’s formation and evolution
differentiation, cratering, basin flooding, surface evolution

Earth’s core has a solid center and liquid outer parts. Evidence for the liquid component of the core comes from
seismic wave studies

Between the crust and liquid core lies a solid material that behaves as a plastic, flowing under high pressure. This material makes up Earth’s

Earth’s magnetic field is thought to result from the dynamo effect, which is
motion in the liquid core that generates temperature currents

One of the best ways to locate the crustal plate boundaries is to identify
the locations of earthquakes

The carbon dioxide in Earth’s early atmosphere was produced when large amounts of gases were released during the accretion process when Earth’s surface temperature was very hot. Most of the carbon dioxide remained in Earth’s atmosphere until it was removed when
Liquid water formed on Earth’s surface and dissolved carbon dioxide causing it to react with other compounds to form limestone and other sediments

The form of electromagnetic radiation that the ozone layer prevents from reaching the Earth’s surface is
ultraviolet radiation

The temperature of Earth is much warmer and more uniform than it would be if Earth did not have an atmosphere. The gas most responsible for trapping heat in Earth’s atmosphere is
carbon dioxide

The greenhouse effect best describes the process by which
heat is trapped by the atmosphere, thus increasing the temperature at a planet’s surface

Free oxygen in Earth’s atmosphere was produced by
living organisms during photosynthesis

Large, reasonably flat and dark areas that cover a good portion of the side of the moon facing earth are referred to as lunar

The craters on the lunar surface were produced by
impacts by asteroids and meteorites

Lunar rocks found in the highlands are
rich in anorthocites, a light-colored-low density rock.

The core of the moon
is small and contains little iron

The large-impact hypothesis proposes that the moon formed as a result of
a Mars-sized object colliding with Earth and ejecting material from Earth’s mantle, some of which fell back to Earth and the rest of which condensed to form the moon.

A problem with the fission hypothesis for the formation of the moon is
the Earth-moon system has less angular momentum then would be expected from such a formation scenario

The craters on Mercury are the result of
impacts of asteroids and meteorites

Lobate scarps on Mercury were probably caused by
shrinkage of the surface as the interior of the planet cooled

Evidence of Mercury’s iron core comes from
unusually high overall density for a planet of its size

The weak (although stronger than expected) magnetic field around Mercury detected by the Mariner 10 spacecraft indicates
the interior of the planet is similar to that of Earth

Spacecraft images of Venus offer little evidence for
major plate motion

Analysis of the surface by spacecraft that have landed on Venus indicates that the surface material consists of

The Magellan and Vanera spacecraft located similar features, called coronae, on the surface of Venus. These features are
circular features probably caused by rising columns of magma under the crust

The major component of the atmosphere on Venus is
carbon dioxide

The atmosphere of Venus contains more carbon dioxide than the atmosphere of Earth. This difference is probably the result of
slightly warmer temperatures on Venus that prevented the accumulation of great amounts of liquid water, thus preventing carbon dioxide from dissolving into liquid water

Evidence of liquid water existing in the Martian past was found by the discovery of
meandering drainage valleys and elongated flow features exposing ancient craters

Evidence of extensive volcanic activity on Mars is found in the
Tharsis region in the northern hemisphere where there are numerous faults and lava flows

The polar caps of Mars consist of
carbon dioxide and frozen water

The atmosphere of Mars consists primarily of
carbon dioxide

The density of the atmosphere on Mars is about
1% of Earth’s atmosphere

The moons of Mars are
Phobos and Deimos

The moons of Mars can briefly be described as
irregular in shape with numerous surface craters

Rover Opportunity photographed small spheres of hematite in the rocks on Mars. These spheres indicate
that liquid water was once present in standing pools at this location

Mar’s atmosphere was much more dense in its past. Mars lost most of its atmosphere because
its escape velocity is slow

The heavy bombardment era had the greatest influence on which stage of Earth’s development

As viewed through a telescope, Jupiter appears as a
disk composed of various colored belts and bands

Saturn, as viewed through a telescope, appears as
a bland and nearly featureless disk

Spacecraft photos revealed active volcanoes on the surface of Jupiter’s moon

The grooved terrain on Ganymede is believed to be
systems of faults in the brittle crust

The ring particles around Jupiter are very small, as evidenced by the observation that light
scatters in the forward direction

The icy rings of Saturn are most likely not composed of particles left from the formation of the planet but rather
debris from collisions between the heads of comets and and icy moons

The core of Jupiter is composed of
heavy elements such as iron, nickel, and silicon

Jupiter’s belts and bands are the result of atmospheric features that have been
stretched and elongated as a result of Jupiter’s rapid rotation.

The atmosphere of Titan is composed primarily of

The Huygens probe to the surface of Titan revealed
pebble-sized chunks of ice

The Cassini division is a large gap in the rings of Saturn. This gap is most likely produced by
resonances between ring particles and the moon Mimas

Two small _____ interact gravitationally with wandering ring particles to keep Saturn’s irregularly twisted F ring confined.
shepherd satellites

Jupiter’s Great Red Spot probably has an extended life because it
originates from deep within the interior of Jupiter.

The belts and zones in the atmosphere of Saturn are less visible than those on Jupiter because
they occur deeper in the cold atmosphere below a layer of methane.

Examination of photographs of Europa taken by the Galileo spacecraft in orbit around Jupiter support the conclusion that
liquid water exists beneath the icy crust

Which of the following planets has its axis of rotation tipped the most

The discovery of Neptune was made as the result of
predictions following mathematical calculations

The very bland appearance of the atmosphere of Uranus is probably caused by
extremely cold temperatures and limited heat flow from its interior

Neptune’s blue appearance is the result of the presence of

The rings of Neptune were discovered as the result of an occulation of a star by Neptune. Astronomers concluded that the rings were not complete because
only one side of the planet yielded the exepected dimming of the starlight

The ring systems of Uranus and Neptune consist of very narrow rings. This narrowness is probably the result of
shepherding satellites controlling the positions of the ring particles.

The oval patterns of grooves (ovoids) on the surface Uranus’ moon Miranda is explained by
internal heat that produced convection in the icy mantle

Dark smudges on the surface of Neptune’s moon Titan appear to be
Methane, converted by sunlight into dark deposits, ejected into space during the eruption of geysers of liquid nitrogen.

Pluto has characteristics that astronomers feel may link it and its moon to the
Kuiper belt objects

The mass of Pluto was determined
from the size of the orbit and period of its moon, Charon.

The Kuiper belt objects called Plutinos are in a 3:2 resonance with the planet Neptune. This means that
These objects orbit the sun twice as Neptune orbits three times

Which of the following are classifications of meteorites
iron and stony

Because of the delicate nature of the carbonaceous chondrites, it is believed that these meteorites came from planetistmals that
orbited far from the sun in regions of the solar system that are very cold and are probably the least altered remains of the solar nebula

The iron meteorites probably formed from
large planetesimals that melted and differentiated to form an iron core

Most often, a meteor is
produced by tiny bits of debris from comets

A meteor shower occurs when
Earth passes through the dust and bits of material left in the orbit of a passing comet

M-type asteroids appear to
be made of iron-nickel alloy and are very bright

The formation of asteroids is the result of
planetary material that never formed into large planets

Many collisions caused planetesimals to fragment into smaller pieces. These pieces probably make up the material known as

The solar wind directs the gas tail of a comet
outward, away from the sun at all times

The nucleus of the coma contains mostly the ices of water, carbon dioxide, and ammonia. The coma is produced when the
sun causes sufficient heating and the ices of the nucleus vaporize to produce a vast cloud of gas and dust

Studies show that the short-period comets cannot originate at a distance thousands of astronomical units from the sun. A closer source for short-period comets is the
Kuiper belt

The spacecraft that intercepted Comet Halley in 1985 and 1986 discovered that the nucleus of Comet Halley is
very dark and irregularly shaped

Jets of high speed gas are seen to be emitted from the nucleus of Comet Halley only
from the sunlit side of the comet

Evidence that Earth has collided with an asteroid-sized object is suggested by a layer of the rare element

The “smoking gun” crater that fits the description of the asteroid impact that may have caused the extinction of the dinosaurs was found
Off the coast of the Yucatan peninsula

The basic unit of life as we know it is
the cell

The element carbon is the physical basis for life on Earth. This atom
is capable of bonding to other atoms and makes long, stable chains that are capable of extracting, storing, and utilizing energy

The information that enables the organism to survive and is transferred from parent to offspring is found in

The info. a cell needs to function is found on the DNA molecule in the form of
four bases and the order in which they appear

The info. regarding cell functioning is carried out of the nucleus by

Evidence that life began in the oceans has been found in
Cambrian period fossils

The Miller experiment consisted of various gases, believed to have been present in the early atmosphere of Earth, exposed to an electrical arc. This experiment resulted in
amino acids, fatty acids, and urea

Hot stars, such as O and A stars, are unlikely to harbor planets suitable for sustaining life because
their stable-energy producing lifespan is too short.

The region of space around a star in which water can remain in liquid form is called
life (or habitability) zone

Scientists think Jupiter’s moon Europa might be able to support life because
there is evidence that below its ice surface there may be liquid water

Several meteorites found in Antarctica have been determined to come from Mars. The evidence for this conclusion lies in the
analysis of trapped gases found in these meteorites with the same abundance as gases found in the Martian atmosphere

The Drake equation is used to
estimate the number of technological civilizations within our galaxy

Of the following factors, the one that is a part of the Drake equation is the
fraction of the lifetime of a star during which a technological civilization is capable of communicating.