Astro Exam 2
T/F: Differentiation is the process in which denser materials such as iron sink to the center of a planetary body, and lighter materials such as silicates rise to the surface. Differentiation is caused by gravity, and it takes place when the interior of the planetary body is hot and molten.
True
If we were to make everything in our solar system 10 billion times smaller, then the Sun would be about the size of a grapefruit, and the Earth would be a poppy seed _____ away.
15 meters
Our atmosphere consists of:
78% nitrogen, 21% oxygen, 1% argon and traces of water vapor (H2O), carbon dioxide (CO2) and other gases
The Sun accounts for about ___ of the mass in our solar system.
99.8%
Radioactive dating of lunar rocks indicates that the lunar highlands are only slightly older than the Maria (the highlands are ~4.2 Gyr old, while the Maria are about 3.3-3.8 Gyr old, where "Gyr" means "billion years"). However, the highlands have 10x more craters than the Maria. An explanation for this is ______.
: Cratering was more intense before the maria formed (before 3.8 Gyr ago). This is known as the period of heavy bombardment, and this produced more craters on the older surface of the lunar highlands.
If we were to land on Venus with a our specially-designed space suits, we would ____.
: come across high temperatures and pressures, an overcast-looking sky, and ground covered with igneous rocks
Which of the following correctly describes the surface of Venus?
: explored by the Venera (USSR) and Magellan (US) missions, 75% of the surface is lowland lava plains, 25% of the surface is made up of continents such as Aphrodite and Ishtar, tallest area includes the Maxwell Mountains
Just like the Moon and the Earth, Mercury has undergone differentiation so that its interior consists of layers: a crust, a mantle and a core. However, Mercury is unique because _____.
: its iron core makes up a much larger percentage of the planet's total mass and radius. The planet may have been formed from iron-rich primitive material close to the Sun, or suffered from significant early impact(s).
Because Mercury is gravitationally locked to the Sun in a 3:2 spin-orbit coupling, it completes one rotation on its axis in 59 Earth days. This is known as a _____. It completes one orbit around the Sun in ____ Earth days, and the time required for the Sun to return to the same spot in the sky (a solar day) is _____ Earth days.
: sidereal day ... 88 ... 176
A useful technique for studying the interior structure of the Earth is _____.
: to study the distinctive travel patterns of seismic waves produced during earthquakes. Seismic waves are useful because S-waves cannot travel through liquids, whereas P-waves can. This allows liquids and solids in the interior to be mapped
Which of the following statements about the water content of Earth is true?
Although 71% of the Earth's surface is covered with water, the oceans are only about 4 km thick compared to Earth's radius (6371 km), therefore water constitutes a small percentage of Earth's volume and mass.
Moon theories: C
Capture theory - The Moon formed elsewhere in the solar system and was captured by Earth's gravity. Problems: the physics of the capture process is difficult to explain. The Moon and Earth share similarities in chemical composition such as the ratios of oxygen isotopes.
Moon theories: A
Fission theory - The Moon was originally part of the Earth, but somehow spontaneously broke away. Problems: this process is not supported by modern calculations, and it is not easy to explain some differences in chemical composition between the Moon and the Earth.
Genetic studies have allowed scientists to construct a phylogenetic tree (or "Tree of Life"). This tree divides living things into 3 domains (Bacteria, Archaea and Eukaryota) based on similarities of their genetic sequences. Based on this tree, humans are most closely related to ____.
Fungi
Fermi
Gamma-rays
The Moon's surface is made up of two types of terrain. These are ______.
Highlands: which are older, lighter colored, heavily cratered mountainous regions made up mostly of low density silicate rocks called anorthosites. And, Maria: which are younger, darker, less-cratered plains made up of basaltic rock formed from volcanic lava.
Select the best statement about the origin of life on Earth from the following.
How life originated on Earth is not clear. Fossil evidence indicates that life existed on Earth about 3.5 billion years ago. These fossils contain colonies of microorganism such as blue green algae (cyanobacteria). Such colonies are still being formed today and are called stromatolites.
Moon theories: D
Impact theory - Proto-Earth was struck by a Mars-sized object called "Theia." During the collision the iron core of Theia sank into Earth, while mantle material was ejected into space. This ejected material coalesced to form the Moon. Problems: no major problems so far, this theory can explain the observed properties of the Moon and the Earth.
The largest space-based telescope of the next decade will be the____.
James Webb Space Telescope (JWST)
spitzer
Infrared (in space)
Asteroids are typically found in the asteroid belt and they are mainly made up of silcate rock, carbon, and metals. The main metal found in asteroids is ______.
Iron
The reflecting telescope, whose working principle is used by most modern telescopes, was invented in 1668 AD by ______.
Isaac Newton
The largest and most massive planet in our solar system is _______. This planet has a diameter of 142,984 km, and a mass of 18,991 x 1023 kg.
Jupiter
The _______ is a region beyond the orbit of Neptune where over 1750 small worlds called Trans-Neptunian Objects (TNOs) are found. The largest of these are called ______.
Kuiper Belt ...... dwarf planets
An upcoming telescope that will have the largest digital camera ever built is the ________. This telescope will have a wide field of view (3.5°), allowing it to scan the entire southern sky approximately once every three nights
Large Synoptic Survey Telescope (LSST), Chile
Which of the following correctly describes our current understanding of life on Mars?
Life on Mars has not been found yet, some organic molecules have been found, life may have existed on Mars and may exist below the surface (protected from the Sun's UV rays), samples returned to Mars in the future may provide more clues.
The first unmanned spacecraft to land on the Moon was ______. The first humans to walk on the Moon were part of ______.
Luna 9 (USSR) ... Apollo 11 (USA)
Which of the following correctly describes the possible sequence of events that might have led to the Mars's current climate?
Mars started off like Earth with liquid water and a thick atmosphere → the atmosphere was lost, possibly due to Mars's weak gravity → temperatures dropped because there were not enough CO2 molecules in the atmosphere to help retain heat → water froze out of the atmosphere → further cooling → runaway refrigerator effect → present-day Mars
The only planets that do not have moons in our solar system are _____.
Mercury and Venus
Please select the correct statement about Mercury's origin
Mercury has a relatively large iron core and thinner mantle and crust. Currently there are two types of theories that try to explain how Mercury formed. Theories that imply mantle material was removed from Mercury by impact or heat. However they have difficulty explaining the presence of volatile material such as potassium. The second type of theory suggests Mercury was formed from iron-rich material near the Sun. This theory can explain the presence of potassium on Mercury.
Please select the correct statement about a recent finding on Mars.
NASA's Curiosity rover found sedimentary rocks in Gale crater. These rocks are formed when sediments such as soil particles settle down in water. These rocks provide evidence of a huge lake that existed on Mars about 3.5 billion years ago. NASA's Opportunity rover found "blueberries" on Mars, these are tiny, round, iron-rich stones that are usually formed in water.
Which of the following accurately describes our current understanding of water on Mars?
No bodies of liquid water found today, although liquid water may have existed in the past. Evidence for past flows of liquid water are: runoff channels, outflow channels and gullies.
Arecibo, Puerto Rico
Radio
Moon theories: B
Sister theory - The Moon formed alongside Earth but independently from primitive material. Problems: the Moon and Earth have very similar ratios of oxygen isotopes, indicating a common origin. The Moon should have had a larger iron core.
Please select the correct statement from the following that compare properties of the Moon and the Earth
The Moon has smaller values than the Earth for size, mass, surface gravity and atmospheric density.
T/F: Since infrared waves are heat radiation, in order for the infrared detector to optimally detect heat from celestial objects, it is important that the detector be shielded from local heat sources and cooled to very low temperatures.
True
Crater counts on Venus indicate that _____.
Venus's surface is 300 to 600 million years old and that the entire planet was resurfaced by widespread volcanism about 300 to 600 million years ago
Which of the following correctly describes our understanding of our neighboring planets?
Venus, Earth and Mars may have had similar origins, with similar atmospheres and water content. Somehow Venus's atmosphere became too thick leading to a runaway greenhouse effect and a hot planet. On the other hand Mars's atmosphere became too thin, leading to a runaway refrigerator effect and a cold planet. Conditions on Earth were favorable for liquid water to exist, for the retention of an atmosphere, and for life.
The planet with the most known volcanic features (that may have been active in the past but are not known to be currently active) is ____.
Venus, it has over 1500 major volcanic features including the large, 300 km wide Sif Mons volcano
Hubble
Visible or optical
Chandra
X-Ray
One explanation for why the dinosaurs went extinct is ________.
a 10-15 km sized object struck Earth about 65 million years ago at Chicxulub in Mexico. This sent huge amounts of dust into the sky, blocking sunlight for months, killing plants and disrupting the food chain. This triggered a series of events that eventually led to the extinction of the dinosaurs.
stratosphere
a calm layer of the atmosphere; ozone is formed here helping to absorb harmful UV rays; temperature increases with altitude in this layer
Ionosphere
a layer that extends from about 80 km to 550 km; it contains charged particles produced by solar radiation; it reflects radio waves and is important for radio communication; Auroras form here
ozone
a molecule containing three oxygen atoms; it is mainly found in the stratosphere; it protects us by absorbing harmful UV radiation
In the Cassegrain focus telescope, light from the secondary mirror is sent to ____.
a small opening in the primary mirror at the base of the telescope. An eyepiece or camera can be attached to this opening, making for a more stable arrangement
Plate tectonics is ______.
a theory that explains how convective currents within the Earth's mantle drive segments of the crust (tectonic or lithospheric plates) to move, producing phenomena such as continental drift, mountain building, earthquakes, volcanoes and so on.
The crater-formation process involves the following steps:
a. Impact: the projectile hits the surface at high speed b. Deep penetration: the object penetrates the surface, its energy is converted to heat, the object and surrounding rock are vaporized and melted c. Crater formation: the vaporized rock explodes to form a circular crater. Debris is thrown outwards to form structures such as an ejecta blanket, secondary craters and crater rays d. Rebound: the compressed surface rebounds to form crater walls and a central peak e. Lava flow: lava can flow from beneath the fractured crust to fill in the crater floor forming maria.
The Spaceguard Foundation is ______.
an international effort dedicated to detecting and tracking Near-Earth Objects so that the threat from space impacts can be better understood.
If we compare our Moon and Mercury, we find that _____.
both the Moon and Mercury are deficient in geologic activity and their surfaces are heavily cratered
Comparing our Moon and Mercury we find that ______.
both the Moon and Mercury lack an atmosphere and running water
The Moon's interior is divided into layers. The outermost layer is the _______ composed of ______. The next layer is the mantle which is composed of silicate rock. The innermost layer is the core which is composed of iron with some nickel.
crust ... granite-like silicate rock
Scarps
cliffs up to 3 km high found on Mercury
Comets are composed mainly of water ice, frozen gases, rock, dust and organic compounds. Comets can retain frozen gases such as carbon dioxide, methane and ammonia because ______.
comets are located in the outskirts of the solar system (the Oort cloud) where it is cold enough for these gases to stay frozen
Aperture
diameter or size of the object
Venus has some distinctive volcanic features. These include i) ______ and ii) ______.
dome-shaped volcanoes produced by thick, viscous lava ... Coronae: produced by lava which exerts an upward pressure from below the surface causing the surface to bulge and crack. An example is the "Miss Piggy" Corona
If we were to land on Mars in our special space suits, we would ____.
encounter a surface covered with red soil, various igneous and sedimentary rocks, temperatures somewhere between 25 °C and -150 °C, a gentle to moderate wind throwing up dust devils in the afternoon, some places with water buried in the ground, and clouds of water-ice or CO2-ice at high elevations
Which of the following correctly describes the geologic properties of Venus?
energy released by convection currents in the mantle generate forces that push and stretch the crust producing features such as fractures, rift valleys and mountains (such as the Maxwell Mountains on the Ishtar continent
We see a much larger number of craters on the Moon than on the Earth. This is most likely because ______.
evidence of craters on Earth have been erased by plate tectonics and erosion
Which of the following correctly describes Mars?
explored by rovers such as "Curiosity," about half the diameter of Earth, no magnetic field, terrain is covered with red soil and is about evenly split between highlands (including prominent volcanic peaks such as Olympus Mons) and younger volcanic plains (including the very deep Hellas Basin)
Exosphere
extends from 700 km to 10,000 km above Earth's surface merging into solar wind; contains very low density gas; most satellites orbit here
Greenhouse gases such as CO2 and CH4 are a concern because ______.
greenhouse gases retain heat and raise the surface temperature of Earth. The greater the concentration of greenhouse gases, the warmer Earth becomes
Which of the following correctly describes the properties of the planet Mars?
half the size of Earth, has two moons, cold and dry with polar ice caps, red colored iron oxides in the soil, rotation rate similar to Earth, second closest planet to Earth, strong seasonal variations in temperature, may have had liquid water in the past
Density of 5.4 g/cm3
higher density of Mercury due to a larger iron core
SOFIA
infrared (in the stratosphere)
The angular resolution of radio telescopes can be improved by connecting more than one radio dish together so that they function as one big telescope where the separation between the dishes can be varied. This technique is known as _____.
interferometry
Venus has a high surface temperature (T ≈ 430 °C) mainly because _____
it has a thick atmosphere containing carbon dioxide that retains heat by the greenhouse effect
The further away planets are from the Sun, the colder they are. Mercury has a high surface temperature (T ≈ 280 to 430 °C) because __________.
it is close to the Sun and receives a lot of heat energy per unit surface area
When using crater counts to estimate the age of Venus's surface, _____.
it is important to consider the effect of the thick atmosphere, craters larger than about 30 km in diameter will more likely have been caused by a single object (without being stopped or broken up by the atmosphere) and are a more reliable measure of the surface's age
Hellas Basin
large impact basin in the southern hemisphere of Mars, contains the lowest point on Mars (about 7 km deep)
Maria
large volcanic plains made of dark basalt rock found on the Moon
Tharsis bulge
large volcanic plateau on Mars; formed by bulging of the martian surface due to tectonic forces from the mantle below
Olympus Mons
largest known volcano in the solar system; taller than Mount Everest (about 25 km high); found in the Tharsis region of Mars
Atmosphere
layer of gases that surround Earth; these gases are retained by the force of gravity, and they exert a pressure of 1 bar at sea level
objective
lens or mirror that collects and focuses light from a source to produce an image
there are two main types of telescopes: refractors where the objective is a _____, and reflectors where the objective is a _____.
lens......mirror
The small telescope essentially consists of an objective that serves as a _____, and an eyepiece that _____.
light bucket.....magnifies the image and redirects it to the eye
A CCD (Charged Couple Device) works on the principle that________.
light falls on silicon-containing pixels releasing electrons by a process known as the photoelectric effect. These electrons then produce an electric current or a digital signal that is processed using electronic components.
The Moon has a lower average density of 3.3 g/cm3 compared to Earth's average density 5.5 g/cm3. This indicates that the Moon is mostly made up of _______.
lighter silicate rocks and is depleted in heavier materials like iron and metals
Valles Marineris
long rift valley on Mars; as wide as the US; formed when forces released by mantle convection currents pulled the crust apart (tectonism); it has been eroded by water and wind
Rilles
long winding valleys found on the surface of the Moon
Density of 3.3 g/cm3
lower density of the Moon due to a smaller iron core
Moons in our solar system are typically made up of frozen water, rocks and ______.
metals
Broken up fragments of rock that can burn up in our atmosphere producing "shooting stars" are called ____. When these fragments fall to ground they are called _____.
meteors.....meteorites
Which of the following correctly describes the properties of the planet Venus?
morning or evening star, closest planet to Earth, slowest rotator, turns upside down, sidereal day is longer than a year, inhospitable, thick atmosphere with a very high pressure, hot enough to melt lead
The 1.2 mile wide Meteor Crater (or Barringer Crater) in Arizona was formed about 50,000 years ago by a _____ meteorite about _____ in diameter.
nickel-iron ... 50 meter
telescope
optical instrument that helps in the observation of distance objects by collecting light
The major change that possibly allowed living things to leave the oceans and colonize the land was ______.
oxygenation of the atmosphere by cyanobacteria, followed by the formation of ozone which provided protection from the harmful UV rays of the Sun
Venus has a thick atmosphere with high surface temperatures (~700 K or 430 °C). It is believed that these conditions were the result of a runaway greenhouse effect. Which of the following scenarios best describes the series of events that might have led to the runaway greenhouse effect on Venus?
planet starts off with an Earth-like climate → a period of extra heat from the Sun causes evaporation of water and release of CO2 from rocks → these gases retain heat by the greenhouse effect → more water vapor and CO2 are released → more heat retention → runaway greenhouse effect → warm planet with a thick atmosphere
According to the solar nebula theory, our solar system formed from a spinning cloud of gas and dust. Material at the center of the disk collected to form the Sun, and the remaining material clumped to together to form ______ (≤ 100 km wide) which later formed the planets. Evidence for such circumstellar disks has been found around other young stars
planetesimals
Estimating the age of the solid surface of a planetary body can be made difficult by ______.
processes such as volcanism and weathering which can erase the history of previous impacts
Mercury's rotation rate was first correctly measured using _____.
radar astronomy: the amount of widening of the returned radar signal due to the Doppler effect from Mercury's rotation allowed its rotation rate to be determined
The inner terrestrial planets are composed mainly of _____, while the Jovian planets are composed mainly of _________.
rocks and metals.....gases and ices
A region at a convergent boundary where a denser tectonic plate is forced beneath a lighter tectonic plate is known as a ______. Earthquakes and volcanoes can occur at such regions. Recent examples are the 2004 earthquake and tsunami in Indonesia and the 2011 earthquake and tsunami in Japan.
subduction zone
Our solar system consists of eight planets, the inner ______ that have smaller sizes and masses but higher densities, and the outer _______ that have larger sizes and masses but lower densities.
terrestrial (or Earth-like) planets......giants (or Jovian) planets
The reason why stars "twinkle" in the night sky is that _______.
the Earth's atmosphere contains small pockets or cells of gas at different temperatures and densities. These cells bend starlight in different directions so that when it reaches our eyes the stars appears to twinkle. Planets on the other hand are closer to us, they appear larger in the sky and although some portions of the planet's light may be distorted by the atmosphere, the remaining light is not affected and thus the light from the planets appears more stable.
After landing on Venus with our special space suits, if we were to sample the atmosphere we would find ____.
the atmosphere is 96.5% carbon dioxide gas, 3.5% nitrogen and very little oxygen to help us breathe
Earth's magnetic field is believed to be produced by _____. Earth's magnetic field is important because it prevents the solar wind from stripping away Earth's atmosphere, and it protects us from harmful radiation.
the combined effects of the motion within Earth's liquid-iron core and the rotation of the Earth on its axis
When we compare the composition of the outermost layer of the Earth (the crust) and the composition of the entire Earth, we see that _____.
the crust is mainly made up of lighter elements such as oxygen, silicon and aluminum, whereas the entire Earth has a larger proportion of iron. This can be explained by the process of differentiation, where denser elements sink to the center of the planet and lighter (less dense) elements rise to the top under the influence of the force of gravity
Focal length
the distance between the lens or mirror and its focal point
Since the rate of impact by projectiles from space has generally stayed constant for several billion years, we can estimate the age of a planetary body's solid surface by counting the number of craters. The logic behind this method is ______, the older the surface.
the larger the number of craters seen on the surface
Troposphere
the lowest layer of the atmosphere, containing 75-90% of the atmosphere's mass; weather occurs here
Radioactive dating of rocks is based in the principle that ____.
the older the rock, the more of its parent radioactive nuclei will have decayed to daughter nuclei. Half-life is a measure of how long it takes for half the parent nuclei decay.
Focal point
the point where light rays from a lens of mirror meet or converge
Mesosphere
this layer extends from about 50 to 80 km above the surface; temperature drops with altitude; meteors burn up here; and the highest clouds (noctilucent clouds) form here
Earth's crust is made up of _______.
three main types of rocks: igneous rocks (such as basalt and granite), sedimentary rocks (e.g., sandstone, shale and limestone), and metamorphic rocks (e.g., marble).
Radar astronomy works on the same principle that the police use to detect speeding cars. There are two components, a __________ that sends ______ waves to a celestial source, and a receiver that detects the reflected waves.
transmitter.....radio
The difference between weather and climate is ______.
weather is local, current state of the atmosphere, while climate refers to the long-term effects of the atmosphere that can last for decades or centuries. Changes in climate are hard to detect on short-time scales, but their additive effects can be devastating such as the extinction of life
