Days, months, years and seasons

Home learning focus

Learn about days, months, years and seasons.

This lesson includes:

  • one video explaining days and years
  • one video explaining how the seasons change
  • two activities


In this video, Tim Peake introduces Prof. Brian Cox who explains why there are days and years on Earth.

What are days and years?


A day is how long it takes a planet to complete one spin on its axis.

For Earth, this is 24 hours.


A month is how long it takes for our Moon to complete one orbit around the Earth.

The Moon will appear to change its shape throughout a month; We call these the phases of the Moon.

On Earth, one month is around 28 days.


A year is how long it takes a planet to complete one orbit of the Sun.

The Earth does this in about 365 days.

The length of a year depends on how far from the Sun a planet is in the Solar System. Mercury is the nearest to the Sun so has a shorter year than Neptune, which is furthest away.

planetlength of year (in Earth days)
Mercury88 days
Venus225 days
Earth365 days
Mars687 days
Jupiter4,333 days
Saturn10,759 days
Uranus30,687 days
Neptune60,190 days


The Earth is tilted on its axis so the UK will change its distance from the Sun throughout the year. This is why we get the seasons.

The Earth is in the northern hemisphere, so:

When the UK is tilted toward the Sun:

  • it is summer
  • it will be warmer
  • there will be more daylight and the days will be longer

When it's tilted further away:

  • it is winter
  • it will be colder
  • there will be less daylight and the days will be shorter

This animation explains this in more detail.

How seasons change through the year


There are lots of ways to try out your science skills.

Activity 1


See what you remember about days, months and years with this quiz.

Activity 2

Test your knowledge of the seasons with this cut and stick downloadable worksheet from Beyond.

You will need scissors and glue to complete this activity.

Seasons worksheet

There's more to learn

Have a look at these other resources around the BBC and the web.

KS3 Physics
11-14 Physics
Bitesize Daily lessons