Grade 9 Space

What is space?

The vast region beyond Earth's atmosphere that contains stars, planets, galaxies, gas, dust, and other objects.

What produces light in space?

Objects that create their own light, such as stars. The Sun is an example.

What reflects light in space?

Objects that do not produce their own visible light but reflect light from another source, such as planets, moons, asteroids, and some comets.

What is the difference between a luminous and non-luminous object?

A luminous object produces its own light, while a non-luminous object reflects light from another source.

What is a star?

A massive ball of extremely hot gas that produces its own light and energy through nuclear fusion.

What is a galaxy?

A huge collection of stars, gas, dust, and other objects held together by gravity.

What is the Milky Way?

The galaxy that contains our Solar System.

What is gravity?

A force of attraction between objects that have mass.

What is space exploration?

The investigation and study of objects and conditions beyond Earth's atmosphere using spacecraft, satellites, telescopes, and other technology.

Why is space exploration important?

It helps us understand the universe, Earth, the Solar System, and the possibility of life beyond Earth.

What is rotation?

The spinning of an object around its own axis.

What is revolution?

The movement of one object around another object.

What causes day and night on Earth?

Earth's rotation on its axis causes different parts of Earth to face toward or away from the Sun.

How long does Earth take to rotate once?

About 24 hours.

How long does Earth take to orbit the Sun once?

About 365.25 days.

What causes the seasons on Earth?

Earth's 23.5° axial tilt combined with Earth's revolution around the Sun.

How does the Moon affect Earth?

The Moon's gravity causes most of Earth's ocean tides and it also helps stabilize Earth's axial tilt.

What causes ocean tides?

Mainly the gravitational pull of the Moon, with a smaller effect from the Sun.

What does the Earth orbit?

The Sun.

What does the Moon orbit?

Earth.

What is a planet?

A large, nearly spherical object that orbits a star and has cleared most other objects from its orbital path.

What is a dwarf planet?

A nearly spherical object that orbits the Sun but has not cleared other objects from its orbital path.

What is a moon?

A natural satellite that orbits a planet or dwarf planet.

What is an asteroid?

A rocky or metallic object that orbits the Sun and is generally much smaller than a planet.

What is a comet?

An icy object made of ice, dust, and rock that orbits the Sun and can develop a glowing coma and tail when it gets close to the Sun.

What is a meteoroid?

A small piece of rock or metal traveling through space.

What is a meteor?

The streak of light produced when a meteoroid enters an atmosphere and heats up.

What is a meteorite?

A meteoroid that survives passing through an atmosphere and reaches the surface of a planet or moon.

What is the difference between a meteoroid, meteor, and meteorite?

A meteoroid is in space, a meteor is the streak of light in an atmosphere, and a meteorite reaches the ground.

What is the Solar System?

The Sun and all of the objects that orbit it, including planets, dwarf planets, moons, asteroids, and comets.

What is the Sun?

The star at the centre of our Solar System.

What is the Sun mostly made of?

Hydrogen and helium.

How does the Sun produce energy?

Through nuclear fusion, mainly combining hydrogen nuclei to form helium.

What is nuclear fusion?

A process where small atomic nuclei combine to form a larger nucleus and release a large amount of energy.

Why is the Sun important to Earth?

It provides the light and heat energy needed for life and drives processes such as Earth's climate and weather.

What is solar radiation?

Energy from the Sun that travels through space as electromagnetic radiation.

What is the Sun's gravity responsible for?

Keeping planets, dwarf planets, asteroids, comets, and other objects in orbit around the Sun.

What is a sunspot?

A relatively cooler, darker region on the Sun's visible surface caused by strong magnetic activity.

What are solar flares?

Sudden bursts of energy and radiation from the Sun's surface or atmosphere.

What is solar wind?

A stream of charged particles continuously flowing outward from the Sun.

How can solar activity affect Earth?

It can interfere with satellites, radio communication, GPS systems, power grids, and can produce auroras.

What is an aurora?

A natural light display caused by charged particles from the Sun interacting with gases in Earth's upper atmosphere.

What is a star made of?

Mostly hydrogen and helium, along with small amounts of other elements.

What determines a star's colour?

Its surface temperature.

What colour are the hottest stars?

Blue or blue-white.

What colour are the coolest stars?

Red.

What colour is the Sun?

White when viewed from space, although it often appears yellow from Earth's surface.

What is a star's brightness?

The amount of light we receive from the star.

What is luminosity?

The total amount of energy a star emits per unit of time.

What is apparent brightness?

How bright a star appears from Earth.

What factors affect how bright a star appears?

Its luminosity and its distance from Earth.

What is a star's temperature?

A measure of how hot the star's surface is.

What is the relationship between star temperature and colour?

Hotter stars appear bluer, while cooler stars appear redder.

What is the Big Bang theory?

The leading scientific explanation that the universe began in an extremely hot, dense state and has been expanding ever since.

Did the Big Bang happen as an explosion into empty space?

No. The Big Bang describes the expansion of space itself from an extremely hot and dense early state.

What evidence supports the Big Bang theory?

The expansion of the universe, cosmic microwave background radiation, and the observed amounts of light elements such as hydrogen and helium.

What is cosmic microwave background radiation?

Weak radiation left over from the early universe that can be detected throughout space.

What does it mean that the universe is expanding?

The distances between large groups of galaxies are increasing over time.

What is the Solar Nebula Theory?

The theory that the Solar System formed from a large cloud of gas and dust that collapsed under gravity and eventually formed the Sun and planets.

What is a nebula?

A large cloud of gas and dust in space.

How did the Sun form according to the Solar Nebula Theory?

Gravity caused material in a collapsing solar nebula to gather at the centre, where the Sun eventually formed.

How did the planets form according to the Solar Nebula Theory?

Material in the disk surrounding the young Sun collided and stuck together, gradually forming larger bodies that became planets.

What is the difference between the Big Bang Theory and Solar Nebula Theory?

The Big Bang Theory explains the origin and expansion of the universe, while the Solar Nebula Theory explains the formation of our Solar System.