science unit 2 Flashcards
parts must function well together for the system to run
smoothly.
a system is a
group of related parts that work together
Natural systems exist in nature and
were not created by humans.
The solar system is a
natural system.
A system has certain characteristics:
It has a structure.
The parts of the system are connected to make a whole.
Elements enter the system (inputs), and elements leave the system (outputs).
It has a process that gives a result.
A subsystem is a
smaller system within a larger system.
human-made satellites—
machines placed in orbit around Earth to collect information
spacecraft—
vehicles designed to travel to outer space for communication and exploration
orbital debris—
human-made objects in orbit around Earth that no longer serve a purpose
Like Earth, all planets are pulled into their orbit by the Sun’s
gravitational force.
The difference in gravity also causes the planets to travel in different
orbital paths.
What force does Earth use when it pulls every object near its surface?
a downward gravitational force.
The gravitational force acting on an object is called its
weight.
What does the weight of an object depend on?
mass
But because the Moon’s gravitational force is weaker than Earth’s, your weight on the Moon would be about
one-sixth your weight on Earth.
As the Moon revolves around Earth, one part of the planet always faces the
Moon.
What are the Earth’s geographic poles?
The North Pole and the South Pole.
The act of spinning around an axis is called
rotation
Each rotation takes
one day, or 24 hours
As it rotates on its axis, half of Earth faces the Sun while the other half faces
away from the Sun.
It is day on the part that
and night on the part that
faces the Sun
faces away from the Sun.
What is it called when the Earth goes around the Sun?
a revolution.
For Earth to complete one revolution around the sun, it takes
365 1/4 days.
That ¼ day adds up to an extra full day every four years. So, every fourth year, our calendar has
366 days.
What is the equator?
The imaginary line around Earth
The equator divides Earth into the
Northern and Southern Hemispheres.
when a hemisphere tilts toward the Sun, they experience
The days are
and the temperature is
summer
longer
warmer
that leaves the other hemisphere tilted away from the Sun, so they experience
The days are
and the temperature is
winter
shorter
colder
when the Sun lines with the equator
one hemisphere experiences autumn and the other experiences spring
An orbit that is farthest from the sun is an
aphelion
An orbit that is closest to the sun is a
perihelion
What are the three layers of an inner planet?
crust, a mantle, and a core.
The innermost layer is the core, which is subdivided into an inner and outer
core
The mantle, or middle layer, of the inner planets is mainly made of
minerals with some metal oxides.
The outermost layer is the crust. It is composed of
rock silicates and metals.
The outer planets do not have a solid surface as the terrestrial planets do. They have a small, dense core of rocky material
surrounded by gases.
The gases surrounding outer planets are mostly
hydrogen and helium.
The cores of Jupiter and Saturn consist of an
iron-nickel alloy (mixture) and rock.
The cores of Uranus and Neptune have nickel-iron
alloy with rocks surrounded by a layer of hot fluid.
The fluid in the ice giant’s cores is
made of water, ammonia, and methane.
All outside planets have
moons and rings
Similar to planets, dwarf planets also
orbit the Sun.
Dwarf planets in our solar system are mostly composed of
ice and have a rocky surface but no rings.
Very few dwarf planets have
moons
An atmosphere is an envelope of gas surrounding a
planet or other celestial body.
Earth’s atmosphere contains gases called greenhouse gases. They consist of water vapor, carbon dioxide, methane, and other gases. When solar energy hits Earth’s atmosphere, these gases absorb extra heat, preventing it from reaching Earth’s
surface.
Atmospheric pressure is
The pressure exerted by the weight of the atmosphere on the surface of Earth
Satellites are objects that move around an
object
The moon orbits Earth, so what does that make the Moon?
a natural satelite
A volcano is a crack or hole in the surface of a
planet, often shaped like a cone.
Tectonic plate activity causes
rift valleys
When asteroids, comets, and other bodies collide with planets or moons,
they make flat or bowl-shaped depressions in the surface called craters.
Canyons are .
deep, narrow valleys with steep sides
What created the asteroids in the asteroid belt?
Smaller bodies between Jupiter and Mars colliding with another and breaking apart
How many layers does the sun have?
six
The Core
The Radiative Zone
The Convective Zone
The Photosphere
The Chromosphere
The Corona
The core is the center of the Sun. It is where all the Sun’s energy is produced.
The energy from the core travels to this zone through the movement of high-energy particles, or radiation.
The hotter gases from the base travel to the top of the zone, and the cooler gases sink to the bottom.
The photosphere is the region of the Sun that is visible to us from Earth. This layer is where energy from the interior of the Sun bubbles up and we see it as visible light.
It is about 2,000 kilometers thick.
It appears in the form of a white crown, or corona, during a total solar eclipse.
Solar flares are
tremendous explosions on the Sun
Solar flares are visible as
sudden, rapid, intense variations in the Sun’s brightness.
Solar wind is a
continuous flow of charged particles, such as protons and electrons, from the Sun.
When solar wind reaches Earth, charged particles and energy enter the
atmosphere near the poles, where the planet’s magnetic field is weakest.
A coronal mass ejection (CME) is an
enormous burst of gas released from the Sun into space.
A sunspot is a
dark spot that is visible on the photosphere.
Near-Earth objects are
objects that aren’t planets, but have orbits that bring them into the inner solar system.
What is the main cause of an aurora?
when solar wind enters Earth’s atmosphere, and particles interact with ions
A white dwarf cools down to become a
black dwarf.
A white dwarf is the
result of the core collapse of a low-mass star that sheds its outer layers.
