HW 5 - Ch 7,8

The half-life of a radioactive element is the time it takes for half the sample to decay; we determine how many half-lives have passed by how much of a sample remains the radioactive element and how much has become the decay product. In this way, we have estimated the age of the Moon and Earth to be roughly ________ year.

4.5 billion

The Sun, a star that is brighter than about 80% of the stars in the Galaxy, is by far the most massive member of the solar system. What percentage of the total mass in the solar system does the Sun contain?

99.8%

terrestrial planet

Any of the planets Mercury, Venus, Earth, or Mars, or a planet similar in size, composition, and density to Earth. A planet that consists mainly of rocky material.

radioactivity

Process by which certain kinds of atomic nuclei decay naturally, with the spontaneous emission of subatomic particles and gamma rays.

planetesimal

objects, from tens to hundreds of kilometers in distance, that formed in the solar nebula as an immediate step between tiny grains...

________ is the movement caused within a gas or liquid by the tendency of hotter, and therefore less dense material, to rise and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat

convection

The Earth has a global magnetic field, that is generated in the ________, produces Earth's magnetosphere, which can trap charged atomic particles.

core

The giant planets have dense cores roughly 10 times the mass of Earth, surrounded by layers of ________ and helium.

hydrogen

basalt

igneous rock produced by the cooling of lava; makes up most of Earth's oceanic crust and is found on other planets that have experienced volcanic activity

differentiation

gravitational separation of materials of different density into layers in the interior of a planet or moon

rift zone

in geology, a place where the crust is being torn apart by internal forces generally associated with the injection of new material from the mantle and with the slow separation of tectonic plates

The greenhouse effect is the blanketing (absorption) of ________ radiation near the surface of a planet—for example, by CO2 in its atmosphere.

infrared

The material that would eventually make all the major bodies in our solar system first gathered together as smaller pieces, which astronomers call:

planetesimals

Within the solar nebula, material first coalesced into _________; many of these gathered together to make the planets and moons. The remainder can still be seen as comets and asteroids.

planetesimals

photosynthesis is a complex sequence of chemical reactions through which some living things can use ________ to manufacture products that store energy (such as carbohydrates), releasing oxygen as one by-product

sunlight

core

the central part of the planet; consists of higher density material

solar nebula

the cloud of gas and dust that formed our solar system

subduction

the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate.

Circumstellar disks are a common occurrence around very young stars, suggesting that disks and stars form ________.

together

A mass extinction is the sudden disappearance in the fossil record of a large number of species of life, to be replaced by fossils of new species in subsequent layers; mass extinctions are indicators of catastrophic changes in the environment, such as might be produced by a large impact on Earth.

true

Earth, like the Moon and other planets, has been influenced by the impacts of cosmic debris, including such recent examples as Meteor Crater and the Tunguska explosion.

true

The ages of the surfaces of objects in the solar system can be estimated by counting craters: on a given world, a more heavily cratered region will generally be older than one that is less cratered.

true

Life originated on Earth at a time when the atmosphere lacked O2 and consisted mostly of CO2. Later, photosynthesis gave rise to free oxygen and ozone. Modern genomic analysis lets us see how the wide diversity of species on the planet are related to each other. CO2 and methane in the atmosphere heat the surface through the greenhouse effect; today, increasing amounts of atmospheric CO2 are leading to the global ________ of our planet.

warming

troposphere

the lowest layer of Earth's atmosphere, where most weather occurs

plate tectonics

the motion of segments or plates of the outer layer of a planet over the underlying mantle

crust

the outer layer of a terrestrial planet

Atmospheric circulation (weather) is driven by seasonally changing deposition of sunlight. Many longer term climate variations, such as the ice ages, are related to changes in __________.

the planet's orbital and axial tilt

magnetosphere

the region surrounding the earth or another astronomical body in which its magnetic field is the predominant effective magnetic field.

Which planet in the solar system rotates backwards (It's spin as seen from North is clockwise, rather than counter-clockwise like the rest)?

Venus

fault

(geology) a crack in the earth's crust resulting from the displacement of one side with respect to the other

seismic wave

A vibration that travels through Earth carrying the energy released during an earthquake.

Which of the following are icy dwarf planets, that exist in an ice realm on the fringes of the main planetary system known as the Kuiper belt? Select four.

Eris, Makemake, Pluto, Haumea

bar

a force of 100,000 Newtons

greenhouse gas

a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range

ozone

a heavy molecule of oxygen that contains three atoms rather than more normal two

volcano

a place where material from a planet's mantle erupts on its surface

meteorite

a portion of a meteor that survives passage through an atmosphere and strikes the ground.

comet

a small body of icy and dusty matter that revolves around the Sun

meteor

a small piece of solid matter that enters Earth's atmosphere and burns up

asteroid

a stony or metallic object orbiting the Sun that is smaller than a major planet but that shows no evidence of an atmosphere

granite

a type of igneous rock that makes up most of Earth's continental crust

giant planet

any of the planets Jupiter, Saturn, Uranus, and Neptune in our solar system, or planets of roughly that mass and composition in other planetary systems

half-life

length of time required for half of the radioactive atoms in a sample to decay

Our planet's geology is dominated by plate tectonics, in which crustal plates move slowly in response to convection in the ________.

mantle

When a meteor survives its passage through our atmosphere and falls to Earth, we call it a ________.

meteorite

sedimentary rock

rock formed by the deposition and cementing of fine grains of materials such as pieces of igneous rock or the shells of living things

igneous rock

rock produced by cooling from a molten state

metamorphic rock

rock produced by physical and chemical alteration (without melting) under high temperatures and pressure

primitive rock

rock that has not experienced great heat or pressure and therefore remains representative of the original condensed materials from the solar nebula

Earth is the prototype terrestrial planet. Its interior composition and structure are probed using ________.

seismic waves

mantle

the largest part of Earth's interior; lies between the crust and core

stratosphere

the layer of the earth's atmosphere above the troposphere and below the ionosphere