FEATURES OF THE UNIVERSE

Define the following terms, using scientific language that a year 10 student would understand:

Term Definition

Galaxy A group of millions or billions of stars, with gas and dust, held together by gravitational attraction.

Star Huge ball of gas held together by gravity. The central core of a star is extremely hot and produces energy. Some of this energy is released as visible light, which makes the star glow.

Solar System The collection of eight planets and their moons in orbit round the sun.

Nebula A dust and gas cloud formed in space that is a source of stars. Sometimes used to refer to other galaxies, when their stars appear indistinct.

Supernova A star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.

Constellation A group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure.

Black Hole A region of space having a gravitational field so intense that no matter or radiation can escape.

Asteroids A small rocky body orbiting the sun. Large numbers of these, ranging enormously in size, are found between the orbits of Mars and Jupiter, though some have more eccentric orbits.

Comets A celestial object consisting of a nucleus of ice and dust and, when near the sun, a ‘tail’ of gas and dust particles pointing away from the sun.