science unit 2

Question 1

parts must function well together for the system to run

Answer 1

smoothly.

Question 1

a system is a

Answer 1

group of related parts that work together

Question 2

Natural systems exist in nature and

Answer 2

were not created by humans.

Question 3

The solar system is a

Answer 3

natural system.

Question 4

A system has certain characteristics:

Answer 4

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.

Question 5

A subsystem is a

Answer 5

smaller system within a larger system.

Question 6

human-made satellites—

Answer 6

machines placed in orbit around Earth to collect information

Question 7

spacecraft—

Answer 7

vehicles designed to travel to outer space for communication and exploration

Question 8

orbital debris—

Answer 8

human-made objects in orbit around Earth that no longer serve a purpose

Question 9

Like Earth, all planets are pulled into their orbit by the Sun’s

Answer 9

gravitational force.

Question 10

The difference in gravity also causes the planets to travel in different

Answer 10

orbital paths.

Question 11

What force does Earth use when it pulls every object near its surface?

Answer 11

a downward gravitational force.

Question 12

The gravitational force acting on an object is called its

Answer 12

weight.

Question 13

What does the weight of an object depend on?

Answer 13

mass

Question 14

But because the Moon’s gravitational force is weaker than Earth’s, your weight on the Moon would be about

Answer 14

one-sixth your weight on Earth.

Question 15

As the Moon revolves around Earth, one part of the planet always faces the

Answer 15

Moon.

Question 16

What are the Earth’s geographic poles?

Answer 16

The North Pole and the South Pole.

Question 17

The act of spinning around an axis is called

Answer 17

rotation

Question 18

Each rotation takes

Answer 18

one day, or 24 hours

Question 19

As it rotates on its axis, half of Earth faces the Sun while the other half faces

Answer 19

away from the Sun.

Question 20

It is day on the part that

and night on the part that

Answer 20

faces the Sun

faces away from the Sun.

Question 21

What is it called when the Earth goes around the Sun?

Answer 21

a revolution.

Question 22

For Earth to complete one revolution around the sun, it takes

Answer 22

365 1/4 days.

Question 23

That ¼ day adds up to an extra full day every four years. So, every fourth year, our calendar has

Answer 23

366 days.

Question 24

What is the equator?

Answer 24

The imaginary line around Earth

Question 25

The equator divides Earth into the

Answer 25

Northern and Southern Hemispheres.

Question 26

when a hemisphere tilts toward the Sun, they experience The days are and the temperature is

Answer 26

summer longer warmer

Question 27

that leaves the other hemisphere tilted away from the Sun, so they experience The days are and the temperature is

Answer 27

winter shorter colder

Question 28

when the Sun lines with the equator

Answer 28

one hemisphere experiences autumn and the other experiences spring

Question 29

An orbit that is farthest from the sun is an

Answer 29

aphelion

Question 30

An orbit that is closest to the sun is a

Answer 30

perihelion

Question 31

What are the three layers of an inner planet?

Answer 31

crust, a mantle, and a core.

Question 32

The innermost layer is the core, which is subdivided into an inner and outer

Answer 32

core

Question 33

The mantle, or middle layer, of the inner planets is mainly made of

Answer 33

minerals with some metal oxides.

Question 34

The outermost layer is the crust. It is composed of

Answer 34

rock silicates and metals.

Question 35

The outer planets do not have a solid surface as the terrestrial planets do. They have a small, dense core of rocky material

Answer 35

surrounded by gases.

Question 36

The gases surrounding outer planets are mostly

Answer 36

hydrogen and helium.

Question 37

The cores of Jupiter and Saturn consist of an

Answer 37

iron-nickel alloy (mixture) and rock.

Question 38

The cores of Uranus and Neptune have nickel-iron

Answer 38

alloy with rocks surrounded by a layer of hot fluid.

Question 39

The fluid in the ice giant's cores is

Answer 39

made of water, ammonia, and methane.

Question 40

All outside planets have

Answer 40

moons and rings

Question 41

Similar to planets, dwarf planets also

Answer 41

orbit the Sun.

Question 42

Dwarf planets in our solar system are mostly composed of

Answer 42

ice and have a rocky surface but no rings.

Question 43

Very few dwarf planets have

Answer 43

moons

Question 44

An atmosphere is an envelope of gas surrounding a

Answer 44

planet or other celestial body.

Question 45

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

Answer 45

surface.

Question 46

Atmospheric pressure is

Answer 46

The pressure exerted by the weight of the atmosphere on the surface of Earth

Question 47

Satellites are objects that move around an

Answer 47

object

Question 48

The moon orbits Earth, so what does that make the Moon?

Answer 48

a natural satelite

Question 49

A volcano is a crack or hole in the surface of a

Answer 49

planet, often shaped like a cone.

Question 50

Tectonic plate activity causes

Answer 50

rift valleys

Question 51

When asteroids, comets, and other bodies collide with planets or moons,

Answer 51

they make flat or bowl-shaped depressions in the surface called craters.

Question 52

Canyons are .

Answer 52

deep, narrow valleys with steep sides

Question 53

What created the asteroids in the asteroid belt?

Answer 53

Smaller bodies between Jupiter and Mars colliding with another and breaking apart

Question 54

How many layers does the sun have?

Answer 54

six

Question 55

The Core The Radiative Zone The Convective Zone The Photosphere The Chromosphere The Corona

Answer 55

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.

Question 56

Solar flares are

Answer 56

tremendous explosions on the Sun

Question 57

Solar flares are visible as

Answer 57

sudden, rapid, intense variations in the Sun’s brightness.

Question 58

Solar wind is a

Answer 58

continuous flow of charged particles, such as protons and electrons, from the Sun.

Question 59

When solar wind reaches Earth, charged particles and energy enter the

Answer 59

atmosphere near the poles, where the planet’s magnetic field is weakest.

Question 60

A coronal mass ejection (CME) is an

Answer 60

enormous burst of gas released from the Sun into space.

Question 61

A sunspot is a

Answer 61

dark spot that is visible on the photosphere.

Question 62

Near-Earth objects are

Answer 62

objects that aren't planets, but have orbits that bring them into the inner solar system.

Question 63

What is the main cause of an aurora?

Answer 63

when solar wind enters Earth’s atmosphere, and particles interact with ions

Question 64

A white dwarf cools down to become a

Answer 64

black dwarf.

Question 65

A white dwarf is the

Answer 65

result of the core collapse of a low-mass star that sheds its outer layers.