AST Exam 3 Flashcards

Terms Definitions
heat waves
newton's 2nd law
Gap in Saturn's rings:
Radiative Energy
energy carried by light
Black Holes:
No support mechanismShrink forever.
Adams and Leverrier predicted the position of Neptune based on its perturbation of
The most abundant element (molecule) in Saturn's atmosphere is
Astronomers must observe the surface of Venus with x-rays because of its thick cloud cover.
When did kepler complete the Rudolphine Tables
Jupiter radiates approximately how much more energy than it receives from the Sun?
Twice as much
Secondary Atmosphere
Earth's atmosphere: this is the ATMOSPHERE WE BREATHE today
Two main "windows" of transparency
Radio and Optical
Which of the following types of molecule is the most abundant in an interstellar molecular cloud?
(Resolution) is sharpest when the ratio of wavelength to telescope size (i.e. lambda/D)
is small
the Larger Particals in the Accretion process.
The largest volcano yet discovered in the solar system is on the planet___
the region in the solar atmosphere from which most of the visible light escapes into space
Who used the first telescope
Galileo Galilei (1564-1642)
Retrograde motion is
a planet appearing to move east-to-west among the stars, 100% from night to night.
As we look deeper and deeper into space, we see more and more galaxies, galaxy clusters, and superclusters. A redshift survey of the universe was performed in the 1980s by astronomers at Harvard University. They mapped the locations of galaxies within about 200 Mpc of the Milky Way. It indicates that galaxies and galaxy clusters are arranged in a network of filaments (walls) surrounding large, empty regions of space known as voids. Some voids measure 100 Mpc across. There is a resemblence to beads on a string. It appears that galaxies and galaxy clusters are spread across the surfaces of gigantic "bubbles" in space. There is a region in Figure 16.21 outlined in red. This is an extended sheet of galaxies known as the Great Wall and measures 70 Mpc by 200 Mpc. Figure 16.22 on page 448 shows a more recent redshift survey. Numerous filaments (walls) and voids are present.
The source of a protostar's energy is:
gravitational contraction
Our most detailed knowledge of the Jovian planets come from
spacecraft exploration
celestial meridian
(the curve) passes through North and South horizon points (NCP and SCP) and the zenith
In the solar nebular theory, the dusty disk condensing around the Sun's equator became the ecliptic plane in which the planets then formed
apparent brightness
a supernova that occurs when an accreting white dwarf reaches the white-dwarf limit, ignites runaway carbon fusion, and explodes like a bomb; often called a type la supernova
jet of hot gas shooting upward into the chromosphere
binary-star system
two stars revolving about each other; a double star
A planetary (or lunar) surface that shows very few or no curves is:
Relatively young.
Besides knowing a star's apparent magnitude, we need to know which of the following in order to determine its absolute magnitude?
its distance from us
cosmological redshift
The component of the redshift of an object that is due only to the Hubble flow of the universe. Photons of light that travel through space are attached to the fabric of the expanding universe. As the universe expands, photons of light are stretched to longer wavelengths. The cosmological redshift is a consequence of the expansion of the universe. It is convenient for cosmologists to use redshift for expressing time because it measures the amount by which the universe has expanded since the photon was emitted. The amount of expansion is related to time.
Hot, faint stars that appear in the lower, left-hand corner of the HR diagram are:
white dwarfs
P waves travel _______ and thus arrive _______ than do the S waves
faster, sooner
The longer the wavelength of light the lower its ___ and ___
frequency; energy
Property of Star - Temperature
measured by absence/presentation of absorption lines in spectrum
ranges from 3,000 - 30,000 K
A layer of gas that surrounds a planet or moon, usually very thin compared to the size of the object
Globular Star Cluster
Large amounts of older stars, round and density packed with stars.
The gas(es) in Earth's atmosphere that contribute(s) most to the destruction of ozone:
CFC (Chloro-FluoroCarbon) gases.
The time required for the moon to make one complete circuit around the Zodiac is approximately
one month
Cepheids are pulsating variable stars, and their pulsation periods are directly related to their true luminosities. Hence, we can use Cepheids as "standard candles" for distance measurements.
Why are Cepheid variables important?
Essentially, the Great Red Spot on Jupiter is
a large cyclonic storm
The first stars that formed the Milky Way now
have chaotic orbits
astrometric (visual) binary
a binary star system in which both stars can be resolved through a telescope
Which of these elements had to be made in a supernova explosion?
a. calcium b. uranium c. oxygen
b. Uranium
How do you calculate how much of radioactive material is left given the amount of half-lives passed?
2^amt. of half-lives
If the moon is past `new' and has not yet reached first quarter, it is called:
waxing crescent.
The "Milky Way" is:
a "cloud" of stars first reported to Europe by Magellan.
Active galaxies are very luminous because they
contain black holes in their core
Shift in hotter black body
Wavelength would be shorter (bluer) or left in the figure
Which of the following surface features are found on the moon?
Craters and rays; rilles; maria; highlands.
What do pulsars appear to be?
rotating neutron stars immersed in hot gas
Milky Way Galaxy
a galaxy that is 75 ly in diameter and 30,000 ly thick at the center
When did humans learn (by a consistent model) that the Earth is not at the center of the universe?
Within the past 600 years.
What 3 things did Galileo discover about the Sun, Saturn, and Venus
Sun: Its rotation had imperfections we call sunspotsSaturn: Giant moons on either side, now called ringsVenus: a range of phases.
What happens to the core of a star after a planetary nebula occurs?
it becomes a white dwarf
In noting that the Earth is "differentiated", we mean that
the density increases as you descend downward toward the core
The largest known black holes
lie in the centers of the most massive galaxies
Changes in Earth's crust by plate tectonics are driven by:
Internal heat flow from within the earth.
Why is the far side of the Moon never seen by people on Earth?
Synchronous rotation of the Moon.
In terms of composition, the Jovian planets are
more like the Sun than are the Terrestrial planets
The ion tail of a comet:
Always points away from the sun and is gas release from the comet by the sun's heat and ionized.
Angular diameter of the Earth vs the Moon
From Earth, the Sun and Moon have about the same angular diameter.
Two stars both have parallaxes of 0.023", but star A has apparent magnitude +2.3, while star B is magnitude +7.3. Which statement is true?
Star A is both 100× brighter and more luminous than star B
The averae rate of erosion on the Moon is far less than here because
the Moon lacks wind, water, and an atmosphere
Ch.19 Q#10: What do we mean by atomic hydrogen gas? How common is it, and how do we map its distribution in the galaxy?
other than ionized, hot gas, it is a gas cool enough that hydrogen stays neutral. It makes up most of the gas in the milky way but only makes up a few percent of the galaxy's total mass. We can map it by radio observations
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