New
New
Year 7

Stars, galaxies and the universe

I can describe what stars and galaxies are and explain how they look when seen from Earth.

New
New
Year 7

Stars, galaxies and the universe

I can describe what stars and galaxies are and explain how they look when seen from Earth.

Lesson details

Key learning points

  1. The Sun is a star, an extremely hot sphere of gas that emits light.
  2. The stars in the night sky are much smaller and dimmer than the Sun because they are much further away.
  3. A light-year is the distance light travels in one year. This is large enough to be suitable for distances in space.
  4. In the universe, stars are found in groups called galaxies, with billions of stars in each one.
  5. There are billions of galaxies in the universe.

Common misconception

The Sun is not a star.

Make it clear that the only reason the Sun looks different to the stars in the night sky is because it is so much closer to Earth. Use visual examples to show what the Sun and/or other stars would look like at greater distances.

Keywords

  • Star - A star is an extremely hot sphere of gas that emits light.

  • Light year - A light-year is the distance light travels in one year.

  • Billion - 1 billion = 1 000 000 000 (one thousand million).

  • Galaxy - A galaxy is a group of billions of stars.

  • Universe - The name for the whole of space and everything in it is the universe.

A video showing a 'zooming out' sequence from Earth to the scale of galaxies can be very powerful. Calculations involving light-years (distance travelled by light in a year) may be best left until after the speed, distance and time relation has been introduced in a future topic, so are not included.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
What is the nearest star to us on Earth?
the Moon
Correct answer: the Sun
Proxima Centauri
Betelgeuse
Q2.
What is the Sun mainly made of?
Correct answer: helium and hydrogen gas
glowing rocks
lava
liquid oxygen
Q3.
What is a constellation in the night sky?
all the stars we can see
Correct answer: a group of stars in a pattern
the brightest star in the sky
Q4.
How many planet Earths could you fit into the Sun?
just one
about ten
about a hundred
Correct answer: about a million
Q5.
Which of the following orbit the Sun?
Correct answer: dwarf planets
Correct answer: asteroids
moons
Correct answer: Jupiter
Q6.
How long does it take for light from the Sun to reach Earth?
Correct answer: a few minutes
a few days
a few months

6 Questions

Q1.
What is the Sun?
Correct answer: a star
a planet
a galaxy
a very bright moon
Q2.
Why do the stars in the night sky look different to the Sun, which is also a star?
The Sun is a different kind of star.
The Sun is a much bigger and brighter star than all other stars.
Correct answer: The Sun is much closer to Earth than all other stars.
The Sun is a different colour to all other stars.
Q3.
Match each keyword to the correct definition.
Correct Answer:universe,all of space and everything in it

all of space and everything in it

Correct Answer:solar system,a star and the objects (e.g. planets) in orbit around that star

a star and the objects (e.g. planets) in orbit around that star

Correct Answer:galaxy,a cluster of billions of stars

a cluster of billions of stars

Correct Answer:star,a huge sphere of gas that gives out light

a huge sphere of gas that gives out light

Q4.
What is a light year?
the time taken for light to travel one year
the distance it would take to travel to the nearest star
Correct answer: the distance light travels in one year
a distance of one year, for light
Q5.
Starting with the smallest, put these in order of size from smallest to largest.
1 - moon
2 - planet
3 - star
4 - solar system
5 - galaxy
6 - universe
Q6.
Select the statements about stars that are true.
Stars orbit the Sun at very great distances.
Correct answer: Stars are hot and bright because of reactions happening within them.
Correct answer: Within a galaxy, stars are light years apart.