Outer Space

Sun

The star at the center of the Solar System; the main source of light and heat on Earth.

Star

A big ball of hot gases that gives off light and heat; the Sun is the closest star to Earth.

Moon

Earth’s only natural satellite; it does not make its own light but reflects the Sun’s light.

Planet

A large object that orbits a star; planets do not produce their own light.

Orbit

The path a planet or moon follows as it moves around another object.

Rotation

The spinning of Earth on its axis, causing day and night.

Revolution

The movement of Earth around the Sun, causing the four seasons.

Solar System

The Sun and the objects that move around it: planets, moons, asteroids, etc.

Earth

The third planet from the Sun and the only planet known to support life.

Mercury

The closest planet to the Sun, very hot during the day and very cold at night.

Venus

The hottest planet, called Earth’s 'sister planet' because of its similar size.

Mars

Known as the Red Planet because of its color; scientists believe it might have had water long ago.

Jupiter

The largest planet in the Solar System with a big storm called the Great Red Spot.

Saturn

Known for its beautiful rings made of ice and rocks.

Uranus

Looks blue-green because of methane gas and tilts on its side.

Neptune

The farthest planet from the Sun, known for its strong winds.

Asteroid

A small rocky object that orbits the Sun, most found in the asteroid belt between Mars and Jupiter.

Comet

A space object made of ice, dust, and rock that has a glowing tail when near the Sun.

Meteor

A piece of rock that burns upon entering Earth’s atmosphere, also known as a 'shooting star'.

Meteorite

A meteor that reaches the ground without burning up completely.

Galaxy

A huge group of stars, dust, and gas; we live in the Milky Way Galaxy.

Constellation

A group of stars that form a pattern or picture, e.g., Orion, Big Dipper.

Axis

An imaginary line on which Earth spins.

Eclipse

When one heavenly body blocks the light from another; solar eclipse - Moon blocks the Sun, lunar eclipse - Earth blocks sunlight from the Moon.

Phases of the Moon

The different shapes of the Moon as seen from Earth (New Moon, First Quarter, Full Moon, etc.).

Light-year

The distance that light travels in one year, used to measure very far objects in space.

Gravity

A force that pulls objects toward each other, keeping planets in their orbits.

Universe

Everything that exists: space, stars, planets, galaxies.

Artificial Satellite

A man-made object placed in space to orbit Earth, used for communication, weather, GPS.

Space Probe

A spacecraft that travels to study other planets and heavenly bodies.